Abstract: The present invention has an object of providing a novel peptide that is permeable to the blood-brain barrier. The present invention provides a blood-brain barrier permeable peptide containing an amino acid sequence: SLSHSPQ (SEQ ID NO: 1) (where P may be substituted). The present invention also provides a carrier molecule for intracerebral delivery containing the peptide, a complex composed of the peptide and a target molecule that is allowed to permeate the blood-brain barrier, and a blood-brain barrier permeable composition containing the complex.

Abstract: The present invention addresses to provide a novel membrane permeability-improving agent which can be applied to high molecular drugs. More specifically, the present invention addresses to provide: a drug carrier which can improve the absorption efficiency of a high molecular drug in the small intestine; and a membrane permeation-improving agent containing the carrier. According to the present invention, a cell membrane-permeating peptide can be provided, which comprises an amino acid sequence selected from the group consisting of the following amino acid sequences: DNPGN (SEQ ID NO: 1); SRPAF (SEQ ID NO: 2); NDPRN (SEQ ID NO: 3); and MSVAN (SEQ ID NO: 4). According to the present invention, a cell membrane-permeable composition can also be provided, which comprises the peptide and a biologically active substance.

Abstract: The present invention addresses to provide a novel membrane permeability-improving agent which can be applied to high molecular drugs. More specifically, the present invention addresses to provide: a drug carrier which can improve the absorption efficiency of a high molecular drug in the small intestine; and a membrane permeation-improving agent containing the carrier. According to the present invention, a cell membrane-permeating peptide can be provided, which comprises an amino acid sequence selected from the group consisting of the following amino acid sequences: DNPGN (SEQ ID NO: 1); SRPAF (SEQ ID NO: 2); NDPRN (SEQ ID NO: 3); and MSVAN (SEQ ID NO: 4). According to the present invention, a cell membrane-permeable composition can also be provided, which comprises the peptide and a biologically active substance.

Abstract: Disclosed is an evaluation peptide for evaluating the efficiency of a pretreatment in the quantification of a protein using a mass spectrometer, having high reliability and high general versatility. Also disclosed is an artificial standard protein comprising the evaluation peptide. Further disclosed is a method for quantifying a protein utilizing the artificial standard protein. Specifically disclosed is a method for selecting a peptide which consists of an amino acid sequence not agreeing with that in a naturally occurring protein and a variant thereof and capable of being detected by mass spectrometry and which has an amino acid that can be recognized by a protein-digesting enzyme, and using the peptide as an evaluation peptide for use in the quantification of a protein by a mass spectrometer.

Abstract: An object of the present invention is to provide a method for producing a stable isotope-labeled target peptide fragment in mass spectrometry, which achieves inexpensive and convenient production.

Abstract: An object of the present invention is to provide a method for producing a stable isotope-labeled target peptide fragment in mass spectrometry, which achieves inexpensive and convenient production.

Abstract: Disclosed is an evaluation peptide for evaluating the efficiency of a pretreatment in the quantification of a protein using a mass spectrometer, having high reliability and high general versatility. Also disclosed is an artificial standard protein comprising the evaluation peptide. Further disclosed is a method for quantifying a protein utilizing the artificial standard protein. Specifically disclosed is a method for selecting a peptide which consists of an amino acid sequence not agreeing with that in a naturally occurring protein and a variant thereof and capable of being detected by mass spectrometry and which has an amino acid that can be recognized by a protein-digesting enzyme, and using the peptide as an evaluation peptide for use in the quantification of a protein by a mass spectrometer.

Abstract: There are provided a peptide consisting of an amino acid sequence for simultaneously quantifying absolute amounts of metabolizing enzyme proteins in a biological sample at high sensitivity and a method for using the same. A peptide which can be detected at high sensitivity with a mass spectrometer that enables highly sensitive simultaneous quantification of metabolizing enzymes, intracellular proteins, is selected, and the amino acid sequence thereof is identified. Using a stable-isotope-labeled peptide having the same amino acid sequence as the amino acid sequence of this peptide to be quantified, a mass spectrometry by LC-MS/MS is performed at predetermined concentration levels of the stable-isotope-labeled peptide to create a calibration curve.