Modification and Cross-Linking of Proteins by Glycolaldehyde and Glyoxal: A Model System.
Highly reactive intermediates of the Maillard reaction, such as glycolaldehyde and glyoxal, are precursors in the modification and cross-linking of proteins. Therefore, we investigated ribonuclease A modified by glycolaldehyde and glyoxal, separately. For the first time, various protein species derived by these aldehydes were successfully separated by ion-exchange chromatography and gel permeation chromatography. Highly cross-linked ribonuclease A was obtained in glycolaldehyde incubations. In contrast, glyoxal predominantly led to modified monomeric protein species. These results were verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis and isoelectric focusing. Quantitation of mono- and bivalent protein modifications of the isolated protein species led to a positive correlation between the degree of protein modification and the change of the isoelectric point and molecular weight, respectively. Glycolaldehyde is easily oxidized to glyoxal. However, significantly lower levels of bivalent glyoxal modifications were detected in glycolaldehyde versus glyoxal incubations (glyoxal-lysine dimer, 1.58 ± 0.02 versus 2.86 ± 0.04 mmol/mol of phenylalanine; glyoxal-lysine amide, 2.7 ± 0.1 versus 5.6 ± 0.1 mmol/mol of phenylalanine). In addition, a novel glycolaldehyde-specific lysine-lysine cross-link was identified and putatively assigned as 1-(5-amino-5-carboxypentyl)-4-(5-amino-5-carboxypentyl-amino)pyridinium salt.
['Klaus|Alexander|A|http://orcid.org/0000-0001-9289-5742', 'Rau|Robert|R|', 'Glomb|Marcus A|MA|http://orcid.org/0000-0001-8826-0808']
D000079:Acetaldehyde D003432:Cross-Linking Reagents D017127:Glycation End Products, Advanced D006037:Glyoxal D007526:Isoelectric Point D008239:Lysine D015416:Maillard Reaction D008970:Molecular Weight D010084:Oxidation-Reduction D055503:Protein Multimerization D012259:Ribonuclease, Pancreatic
cross-linking glycolaldehyde glyoxal Maillard reaction ribonuclease A advanced glycation endproducts