Abstract: The invention relates to a method of detecting peptides having amino groups. The method involves digesting a protein into at least two peptides having an amino group. The amino groups are trimethylated under vacuum and then the peptides are detected using mass spectrometry. Another embodiment of the invention provides a method of detecting peptides. The method employs a protein having a lysine residue having an ?-amino group. The protein is digested into at least two peptides. The ?-amino group is then trimethylated under vacuum. The peptides are then detected using mass spectrometry. The method can also be used for a protein having an ?-amino group. Alternatively, a method of detecting peptides is provided for a protein having a lysine residue where the lysine residue has an ?-amino group. The protein is digested into at least two peptides having an ?-amino group. The ?-amino group and ?-amino group are trimethylated under vacuum and the peptides are detected using mass spectrometry.

Abstract: It has been discovered that facile glycation of proteins can be achieved by colyophilization of a protein with a reducing sugar, subjecting the lyophilized mixture to a vacuum (10 to 50 millitor) and incubating at an elevated temperature (50 to 100° C.) for 1 to 24 h. A stable ketoamine derivative is formed with amino groups in the protein and no advanced glycation end products (browning reaction) are observed, as is the case with aqueous glycation procedures. Another novel feature is that the in vacuo glycation reaction takes place with the protonated amine and not the deprotonated amine as is believed to be the case for aqueous glycation reactions. Advantage can be taken of the in vacuo glycation reaction to achieve facile covalent cross-linking of proteins by lyophilizing protein or proteins with compounds containing two or more reducing sugars separated by a linker.

Abstract: The invention relates to a method of detecting peptides having amino groups. The method involves digesting a protein into at least two peptides having an amino group. The amino groups are trimethylated under vacuum and then the peptides are detected using mass spectrometry. Another embodiment of the invention provides a method of detecting peptides. The method employs a protein having a lysine residue having an &egr;-amino group. The protein is digested into at least two peptides. The &egr;-amino group is then trimethylated under vacuum. The peptides are then detected using mass spectrometry. The method can also be used for a protein having an &agr;-amino group. Alternatively, a method of detecting peptides is provided for a protein having a lysine residue where the lysine residue has an &egr;-amino group. The protein is digested into at least two peptides having an &agr;-amino group.