Abstract: A ninhydrin reagent for use in a method for analysing nitrogen-containing compounds, in particular visualising nitrogen-containing compounds by a colour forming reaction, is provided, the ninhydrin reagent comprising ninhydrin; an aqueous buffer; and a temperature-dependent reducing agent, which agent is inactive in the reduction of ninhydrin at a first temperature and active in reducing ninhydrin to hydrindantin at a second temperature, wherein the second temperature is higher than the first temperature. The reagent is particularly useful in the analysis of amino acids.

Abstract: A method for analysing one or more nitrogen-containing compounds, in which the one or more nitrogen-containing compounds are contacted with hydrindantin at an elevated temperature in a contact zone is provided, the method comprising contacting ninhydrin with one or more reducing agents in a heating zone at a first elevated temperature to produce a hydrindantin-containing mixture; and introducing the hydrindantin-containing mixture into the contact zone and contacting the hydrindantin-containing mixture with the nitrogen-containing compounds at a second elevated temperature. The method is particularly suitable for the analysis by visualisation of amino acids.

Abstract: A method of evaluating NASH includes (I) an obtaining step of obtaining amino acid concentration data on a concentration value of an amino acid in blood collected from a subject to be evaluated and (II) a concentration value criterion evaluating step of evaluating a state of a hepatic fibrogenesis in a NASH in the subject, based on the amino acid concentration data of the subject obtained at the obtaining step.

Abstract: A preparation method and its use of derivatization reagent for detecting L-carnitine or D-carnitine are provided. The present reagent is stable. It can be used for detecting L-carnitine or D-carnitine accurately and sensitively. That is to say, the reagent is applied to detecting the amount of synthesized or natural L-carnitine and the amount of mixing D-carnitine. The compound reagent is used for determining the chiral isomers of chemicals, biological reagents, health care reagents, cosmetic, body fluids and various foods, which contain L-carnitine or/and D-carnitine, and optical isomers of other chiral amino acids.

Abstract: A method of evaluating fatty liver related disease includes (I) an obtaining step of obtaining amino acid concentration data on a concentration value of an amino acid in blood collected from a subject to be evaluated and (II) a concentration value criterion evaluating step of evaluating a state of a fatty liver related disease including at least one of fatty liver, NAFLD, and NASH in the subject, based on the amino acid concentration data of the subject obtained at the obtaining step.

Abstract: The methods and compositions provided herein relate generally to IL-10 specific antibodies and uses thereof. More specifically, compositions of humanized IL-10 specific antibodies and methods to use such antibodies in modulating the biological activity of IL-10, particularly in autoimmune disorders and pathogen-mediated immunopathology.

Abstract: There is provided a method of diagnosing a disease state in a subject. The disease state is caused or effected by pneumococcal infection. The method includes obtaining a biological test sample from the subject. The biological sample includes at least one metabolite selected from the group consisting of citrate, trigonelline, acetylcarnitine, acetone, myo-inositol, 3-hydroxybutyrate, glucose and carnitine. A respective concentration of each one of the at least one metabolite is compared with a predetermined concentration value associated with a corresponding one of the at least one metabolite. The predetermined concentration value is indicative of the disease state. For example, the biological sample includes any one of citrate, trigonelline, acetylcamitine, acetone, myoinositol, 3-hydroxybutyrate, glucose and carnitine. As a further example, the biological samples include any combination of citrate, trigonelline, acetylcamitine, acetone, myo-inositol, 3-hydroxybutyrate, glucose and carnitine.

Abstract: Dyes and photoluminescent compounds based on polymethine dyes that contain at least one alkyl-phosphonate or substituted alkyl-phosphonate group, including the synthetic precursors, methods of synthesis, and applications thereof. Certain embodiments include heterocyclic ring systems and polymethine linkages selected such that the resulting polymethine dye is a cyanine dye, a merocyanine dye or a styryl dye.

Abstract: According to the method of evaluating stress of the present invention, amino acid concentration data on the concentration value of amino acid in blood collected from a subject to be evaluated is measured, and a stress state including at least depressive illness and major depressive illness in the subject is evaluated based on the concentration value of at least one of Lys, His, ABA, Asn, Phe, Leu, Ile, Val, Trp, Tyr and Met contained in the measured amino acid concentration data of the subject.

Abstract: The present invention pertains to the field of toxicological assessments of risk stratification of chemical compounds. Specifically, it relates to a method for diagnosing increased peroxisomal proliferation. It also relates to a method of determining whether a compound is capable of inducing such peroxisomal proliferation in a subject and to a method of identifying a drug for treating increased peroxisomal proliferation. Furthermore, the present invention relates to a data collection of characteristic values of at least five metabolites, a data storage medium for the data collection, and a system and a device for diagnosing increased peroxisomal proliferation. Finally, the present invention pertains to the use of a group of metabolites or means for the determination thereof for the manufacture of a diagnostic device or composition for diagnosing increased peroxisomal proliferation in a subject.

Abstract: A method of detection of amino acid sequences and/or identification of proteins and peptides is based on derivatization of peptides or proteins using compounds comprising two or more sulfonyl groups, and subsequent analysis of the derivatized analytes using a mass spectrometer in its negative mode of operation.

Abstract: Reagents and methods are provided that permit simultaneous analysis of multiple diverse small molecule analytes present in a complex mixture. Samples are labeled with chemically identical but isotopically distinct forms of the labeling reagent, and analyzed using mass spectrometry. A single reagent simultaneously derivatizes multiple small molecule analytes having different reactive functional groups.

Abstract: A fast and sensitive method and device for protein sequencing are disclosed. The method uses a combination of Edman degradation chemistry and mass spectrometry to sequence proteins and polypeptides. A peptide degradation reaction is performed on a polypeptide or protein ion reactant in the gas phase. The reaction yields a first ion product corresponding to a first amino acid residue of the polypeptide or protein reactant and a polypeptide or protein fragment ion. The mass-to-charge ratio for the first ion product, or the polypeptide or protein fragment ion, or both, is then determined. The first amino acid residue of the polypeptide or protein reactant is then identified from the mass-to-charge ratio so determined.

Abstract: In alternative embodiments, the invention provides nucleic acid sequences that are genetic polymorphic variations of the human TMEM216 gene, and TMEM216 polypeptide encoded by these variant alleles. In alternative embodiments, the invention provides methods of determining or predicting a predisposition to, or the presence of, a ciliopathy (or any genetic disorder of a cellular cilia or cilia anchoring structure, basal body or ciliary function) in an individual, such as a Joubert Syndrome (JS), a Joubert Syndrome Related Disorder (JSRD) or a Meckel Syndrome (MKS). In alternative embodiments, the invention provides compositions and methods for the identification of genetic polymorphic variations in the human TMEM216 gene, and methods of using the identified genetic polymorphisms and the proteins they encode, e.g., to screen for compounds that can modulate the human TMEM216 gene product, and possibly treat JS, JSRD or MKS.

Abstract: The present invention relates to a stool sample processing method and stool sample processing container the a stool sample processing container provided with a stool collection tool, a suspending solution holding portion and a processing solution holding portion, wherein stool sample preparation solutions consisting of a suspending solution and a stool sample processing solution are respectively housed in a suspending solution holding container and a processing solution holding container, after first mixing a stool sample with the suspending solution and suspending therein, a sealant is released into the suspending solution holding container by pressing on the lower portion of the processing solution holding container, and the resulting stool suspension mixes with the stool sample processing solution that stabilizes the nuclide acid.

Abstract: A method for on-line monitoring of deprotection reaction in a peptide automated synthesizer comprising UV detector is disclosed. A UV source, detector, electronics, and housing are integrated with a line or tube through which liquid reactants flow for periodic measurements in the peptide synthesizer. The method includes determining the progression of the reaction, completion point of the reaction, and the modification of the reaction times and repetitions in real time.

Abstract: Spectroscopic analysis systems and methods for analyzing samples are disclosed. An analysis system may contain an electromagnetic radiation source to provide radiation, a spectroscopic analysis chamber to perform a coherent Raman spectroscopy (e.g., stimulated Raman or coherent anti-Stokes Raman spectroscopy), and a radiation detector to detect radiation based on the spectroscopy. The chamber may have a resonant cavity to contain a sample for analysis, at least one window to the cavity to transmit the first radiation into the cavity and to transmit a second radiation out, a plurality of reflectors affixed to a housing of the cavity to reflect radiation of a predetermined frequency, the plurality of reflectors separated by a distance that is sufficient to resonate the radiation. The spectroscopic analysis system may be coupled with a nucleic acid sequencing system to receive a single nucleic acid derivative in solution and identify the derivative to sequence the nucleic acid.

Abstract: A method of identifying a biopolymer in a sample that includes one or more biopolymers. The biopolymers may be polypeptides, polynucleotides, or polysaccharides. The method makes use of mass spectral datasets. A first dataset includes measured masses of the one or more biopolymers that are in the sample. A second dataset includes measured masses of a collection of fragments of the one or more biopolymers. The method selects a mass from the first dataset and then matches masses from the second dataset with the selected mass. The matched masses represent fragments of the biopolymer with the selected mass. Once the masses in the second dataset have been matched they are compared to determine a monomer sequence for the biopolymer with the selected mass. The method may be repeated with additional masses in the first dataset.

Abstract: Disclosed is a method of analyzing an oxidation state of a methionine residue in a protein sample, which comprises the steps of: inducing a reaction between a protein sample having a methionine residue with an oxidation state to be analyzed, and hydrogen peroxide H218O2 having oxygen atoms labeled by the isotope 18O, to obtain a modified protein sample in which the oxidation state of the methionine residue is stabilized; and subjecting the modified protein sample to a measurement to quantify an oxidation degree of the methionine residue. Preferably, the measurement is a mass spectrometric (MS) measurement using a mass spectrometer. The method can analyze an oxidation state of a methionine residue in a protein sample, in a simple manner, while accurately reflecting an in vivo oxidation state of the methionine residue.

Abstract: Methods and compositions for treating central nervous system diseases and disorders are disclosed.

Abstract: The presently-disclosed subject matter provides biosensors for detecting molecules of interest. The biosensors include a polypeptide capable of selectively-binding glucose, wherein the polypeptide molecule is selected from: an unnatural analogue of wild type glucose binding protein; a fragment of wild type glucose binding protein; and an unnatural analogue fragment of wild type glucose binding protein.

Abstract: A surface grafted conjugated polyelectrolyte (CPE) is formed by coupling a CPE by a coupling moiety to the surface of a substrate. The substrate can be of any shape and size, and for many uses of the surface grafted CPE, it is advantageous that the substrate is a nanoparticle or microparticle. Surface grafted CPEs are presented that use silica particles as the substrate, where a modified silane coupling agent connects the surface to the CPE by a series of covalent bonds. Two methods of preparing the surface grafted CPEs are presented. One method involves the inclusion of the surface being modified by the coupling agent and condensed with monomers that form the CPE in a grafted state to the substrate. A second method involves the formation of a CPE with terminal groups that are complimentary to functionality that has been placed on the surface of the substrate by reaction with a coupling agent. The surface grafted CPEs are also described for use as biosensors and biocides.

Abstract: This invention provides methods, compositions and articles of manufacture for inhibiting binding between A? protein and ABAD in cells. Uses of this invention include, for example, treating Alzheimer's disease; reducing free radical generation, DNA fragmentation, and cytochrome C release in cells; and preserving cell viability by preventing LDH release from a cell.

Abstract: Described herein is an in vitro method for the determination of the formation of endothelins in serious diseases, in particular cardiovascular diseases, inflammations, sepsis and cancer, in whole blood, plasma or serum of a human patient, in which relatively long-lived peptide fragments of the processed primary prepro- or proendothelins are determined which contain neither the actual biologically active endothelin nor its direct precursor big endothelin. In particular, disclosed are antibodies and kits for selectively detecting these fragments.

Abstract: A method for analyzing chemicals includes fractionating a complex sample into at least two sample portions that each include portions of two polypeptides though in different concentration ratios, digesting and performing LC/MS on each of the sample portions, and associating precursor ions observed via LC/MS with their corresponding polypeptide in response to LC/MS-provided intensity data. A set of precursor-ions that has substantially similar intensity ratios in both sample portions is determined to be associated with the same polypeptide.

Abstract: The invention provides compositions and methods for diagnosing a patient as having a myeloproliferative disease by identifying mutations in the MPL gene or gene products.

Abstract: Methods are described for monitoring the amounts of PTH variants in a biological sample by digesting the sample to produce surrogate peptides specific to the targeted PTH variants, and detecting and quantifying the surrogate peptides by selective reaction monitoring (SRM) mass spectrometry, using a set of precursor-to-product ion transitions optimized for sensitivity and selectivity. The PTH variants, or a portion thereof, may be concentrated in the sample by means of immunoaffinity capture or other suitable technique. The mass spectrometric method described herein enables the concurrent measurement of peptides representative of a plurality of targeted PTH variants in a single assay.

Abstract: Method that includes providing plurality of test sites each having first and second layers respectively including inorganic first and second surface sites forming parts of interior of a well, the surface sites having positions and thicknesses being configured for locating thereon portions of unidentified amino acid-containing molecules; exposing each of a first plurality of the test sites to a fluid containing a different one of plurality of pre-identified amino acid-containing molecules and determining bonding signatures onto each of first plurality of test sites; exposing each of second plurality of test sites to another fluid containing unidentified amino acid-containing molecule and determining bonding signatures onto second plurality of test sites; and comparing bonding signatures to determine or exclude identity of unidentified amino acid-containing molecule.

Abstract: This invention relates, inter alia, to detecting and/or measuring succinylacetone and one or more additional biological analytes using mass spectrometry.

Abstract: The invention provides a method for labeling an analyte comprising a primary amino group, the method comprising: a. a labeling process comprising reacting the analyte with a dialdehyde in the presence of a label, wherein the label bears a charge, and b. an analysis process comprising subjecting the labeled analyte to MS, preferably LC-MS-MS. Herein, preferably, the labeling process comprises reacting an analyte with a dialdehyde, wherein the dialdehyde carries a label bearing a charge, to provide a labeled analyte carrying the charge. The present invention also provides a labeling method to provide a labeled analyte carrying a charge, wherein the labeling method comprises a labeling process comprising reacting an analyte with a dialdehyde, wherein the analyte comprises a primary amino group and wherein the dialdehyde carries a label bearing the charge. The dialdehyde is preferably an aromatic dialdehyde, most preferably an aromatic 1,2- or 1,3-dicarboxaldehyde.

Abstract: A method for the prevention or treatment of a condition selected from type 2 diabetes, obesity and metabolic syndrome comprising activating a GITRL pathway. Methods for screening for substances to treat these conditions, diagnosing or predicting these conditions and selecting and monitoring therapies.

Abstract: Methods of identifying polypeptides have been developed using a de novo sequencing technique. Methods use photodissociation and low-energy fragmentation and the spectra of peptide ions obtained therefrom, such as obtained by post-source decay (PSD), have been developed. The methods include photodissociation and the spectra therefrom obtainable from treating ions with predetermined wavelengths of radiation in the vacuum ultraviolet range of the electromagnetic spectrum. The confidence of amino acid assignments based on x-type ions is evaluated by observing complementary y-, v- and w-type ions that provide additional constraints to sequence identification.

Abstract: The present invention provides a peptide degradation reagent with the following characteristics: 1) it has no marked toxicity such as carcinogenicity, 2) it does not produce metastable peaks resulting from excessive degradation property, 3) it does not produce multiply-charged ion peaks which are interference peaks, and 4) it can secure separation and sharpness of peaks. The present invention also provides a method for specifically cleaving N—C? bonds on a peptide backbone using the above-described reagent, and a method of determining the amino acid sequence of a peptide utilizing this specific cleavage. A method for specifically cleaving N—C? bonds on the backbone of a peptide, comprising irradiating the peptide with laser light in the presence of 5-amino salicylic acid. A method for determining the amino acid sequence of a peptide, comprising irradiating the peptide with laser light in the presence of 5-amino salicylic acid to thereby specifically cleave N—C? bonds on the peptide backbone.

Abstract: A system (100) is described for characterizing and/or manipulating molecules. The system may especially be suitable for biological molecules, although the invention is not limited thereto. The system (100) comprises a substrate (110) comprising a nanostructure (120) being suitable for translocation of molecules through the nanostructure (120). It furthermore comprises a means (210) for translocating molecules through the nanostructure (120) and a plasmonic force field generating means (130) adapted for influencing the translocation speed of the particle by applying a plasmonic force field at the nanostructure (120). A corresponding method also is described.

Abstract: Various mass spectroscopy-based methods are provided to improve protein sequencing by detecting z-type product ions generated from the protein. A polypeptide is introduced to a mass spectrometer, and in particular c- and z-type product ions that are generated by selectively fragmenting the polypeptide. The z-type product ions are distinguished from the c-type product ions and the mass-to-charge ratio of at least a portion of the z-type product ions are determined. From the mass of the z-type product ions, a putative chemical composition is identified for at least a portion of the z-type product ions, c-type product ions, or both, which is used to determine polypeptide compositions. Further provided are various methods for reducing spectral noise, instrument calibration and database searching and verification.

Abstract: Multiplex analysis methods for rapid analysis of the presence or amount of two or more biomolecules in a sample are disclosed. Systems implementing such methods are further disclosed.

Abstract: Disclosed are methods for treating a subject suffering from phenylketonuria and/or phenylalanemia. The methods include, in part, enterally administering to the subject a LNAA supplement in which the weight ratio of Leu to Val is greater than 2:1; in which the weight ratio of Leu to iLeu is greater than 3:1; or which includes one or more LNAAs and which further includes Lys. LNAA supplements are also disclosed. Also disclosed are methods for treating a subject suffering from a condition involving a metabolic disorder involving the metabolism of a first amino acid X. The method includes enterally administering to the subject a composition which (i) is substantially free from the first amino acid X and (ii) which includes a second amino acid Y that competes with amino acid X at a gastrointestinal tract transporter.

Abstract: The present invention relates to the use of endogenous reference metabolites and a method for normalization of intensity data corresponding to amounts and/or concentrations of selected target metabolites in a biological sample of a mammalian subject, wherein said intensity data are obtained by a metabolomics analysis method with one or a plurality of endogenous reference metabolites, comprising carrying out at least one in vitro metabolomics analysis method of said selected target metabolites in said biological sample, simultaneously carrying out in the same sample a quantitative analysis of one or a plurality of endogenous reference metabolites or derivatives thereof, wherein said endogenous reference metabolites are such compounds in the biological sample which are present in the subject at an essentially constant level; and wherein said endogenous reference metabolites or derivatives thereof have a molecular mass less than 1500 Da.

Abstract: The present invention relates to methods for analyzing complex mixtures of proteins, both for identification and quantitation of proteins of interest, and in particular, methods of identification and quantitation of proteins present at low levels, using internal standard peptides isobarically tagged at the N and C termini.

Abstract: The present invention relates to a method for diagnosing diabetes or a predisposition thereof, comprising determining at least one metabolite in a test sample of a subject suspected to suffer from diabetes or to have a predisposition therefor and comparing the metabolite to a reference to diagnose diabetes or a predisposition therefor. The present invention further encompasses a collection of metabolites, a data collection comprising characteristic values of metabolites and a storage medium comprising the data collection. The present invention also relates to a system comprising methods or devices for comparing characteristic values of metabolites of a sample operatively linked to a data storage medium. The present invention also encompasses diagnostic methods or devices comprising at least one metabolite and use of the metabolite for the manufacture of diagnostic methods and devices for diagnosing diabetes; and a method for identifying diabetes-related metabolites.

Abstract: The present invention relates to a method for diagnosing a predisposition for diabetes, comprising determining a metabolite in a test sample of a subject suspected to have a predisposition for diabetes and comparing the metabolite to a reference to diagnose the, predisposition for diabetes. Moreover, the present invention encompasses a collection of metabolites, a data collection comprising characteristic values of metabolites and a storage medium comprising the data collection. The present invention also relates to a system comprising methods or devices for comparing characteristic values of metabolites of a sample operatively linked to a data storage medium. Additionally, diagnostic methods or devices comprising a metabolite and its use for manufacture of the diagnostic method or device for diagnosing a predisposition for diabetes are provided, along with a method for identifying diabetes-related metabolites.

Abstract: The invention provides improvements in reagents for use in electron transfer dissociation ionization techniques for use in mass spectrometry, particularly for sequencing peptides and proteins using mass spectrometric techniques involving electro-spray ionization and MS/MS characterization of fragment ions. The novel reagents used in the inventive methods allow for more effective determination of protein sequences, especially of long peptides or post-translationally modified protein fragments. Use of the polycyclic aromatic hydrocarbons azulene, homoazulene, and acenaphthylene, and homodimers and heterodimers thereof, are described.

Abstract: Methods and devices for detecting the presence of a NO forming material (e.g., a material that can form, or is, a nitrogen monoxide molecule) are disclosed based on detection of fluorescence exhibited by NO molecules in a first vibrationally excited state of a ground electronic state. Such excited NO molecules can be formed, for example, when small amounts of explosives are photodissociated. By inducing fluorescence of the material, a distinct signature of the explosive can be detected. Such techniques can be performed quickly and with a significant standoff distance, which can add to the invention's utility. In another aspection of the invention, methods and apparatus for generating electromagnetic radiation are disclosed. Such methods and apparatus can be used in conjunction with any detection method disclosed herein.

Abstract: The present invention relates to a metabolic biomarker set for assessing kidney disease comprising at least two amino acids, at least two acylcarnitines and at least two biogenic amines. Moreover, the present invention relates to a method for assessing kidney disease in a mammalian subject which comprises obtaining a biological sample, preferably blood and/or urine, from the subject and measuring in the biological sample the amount of at least two amino acids, of at least two acylcarnitines and of at least two biogenic amines, as well as to a kit adapted to carry out the method. By employing the specific biomarkers and the method according to the present invention it becomes possible to more properly and reliably assess kidney disease.

Abstract: This invention relates to methods for determining hypersusceptibility of HIV-1 viruses to non-nucleoside reverse transcriptase inhibitors (NNRTIs) based on the viral genotypes. The methods generally comprise detecting, in a gene encoding reverse transcriptase of the HIV-1, the presence of a mutation at codon 65, 69, or 74 alone or in combination with one or more mutations at certain other codons. Combinations of mutation associated with hypersusceptibility to NNRTIs are also disclosed.

Abstract: Method that includes providing plurality of test sites each having first and second layers respectively including inorganic first and second surface sites forming parts of interior of a well, the surface sites having positions and thicknesses being configured for locating thereon portion of unidentified amino acid-containing molecules; exposing each of a first plurality of the test sites to a fluid containing a different one of plurality of pre-identified amino acid-containing molecules and determining bonding signatures onto each of first plurality of test sites; exposing each of second plurality of test sites to another fluid containing unidentified amino acid-containing molecule and determining bonding signatures onto second plurality of test sites; and comparing bonding signatures to determine or exclude identity of unidentified amino acid-containing molecule.

Abstract: A method (100) for analyzing chemicals includes fractionating a complex sample into at least two sample portions that each includes portions of two polypeptides though in different concentration ratios, digesting and performing LC/MS on each of the sample portions (110, and associating precursor ions observed via LC/MS with their corresponding polypeptide in response to LC/MS provided intensity data (170). A set of precursor ions that has substantially similar intensity ratios in both sample portions is determined to be associated with the same polypeptide.

Abstract: A composition for treating damaged tissue and promoting healthy tissue growth, healing and tissue regeneration, wherein said composition comprises an extracellular matrix compound, a surface-active lipid, one or more enantiomerically pure L-amino acids or glycine, a hydrophilic surfactant with a high HLB, as well as vitamins, minerals or trace elements. Not only does it maintain good health, but the components are non-intrusive, bio-safe, non-coalescent and can mimic normally occurring stem-cells within a body. When applied to diseased tissues, the subject compositions can stimulate, facilitate, and accelerate protein synthesis for the regeneration of diseased organs and tissues. The healing efficacy of these tissue components gives us further appreciation of the protective action of human tissue over and above and other than the immune protective system or perhaps an integral component part of the immune system.

Abstract: The present invention provides a method for analyzing the C-terminal amino acid sequence of a peptide by using a reaction for successively releasing the C-terminal amino acids of the peptide, which method can suppress, when successively releasing the C-terminal amino acids of a peptide of long amino acid length, such a undesirable side reaction as cleavage of peptide bond in the intermediate position of the peptide and can carry out the chemical treatment thereof under widely applicable conditions; In the method, a dry sample of a peptide with long amino acid length is beforehand subjected to an N-acylation treatment; by using a reaction reagent where an alkanoic acid anhydride is combined with a small amount of a perfluoroalkanoic acid, successive release of C-terminal amino acids is conducted under mild conditions; a hydrolysis treatment is applied; then, selective fragmentization at site of arginine residue is performed by digestion by trypsin; thereafter, decreases in molecular weight are measured for the

Abstract: A clickable cross-linker compound provides an easily scanned reporter ion for effective and efficient cross-linking and identification of intermolecular and intramolecular interactions of proteins and peptides.