title: [Interaction of pyridoxal-5-phosphate with human serum albumin and pancreatic ribonuclease].
abstract: Pyridoxal-5-phosphate (in a lesser degree, pyridoxal) interacts with both non-protonated and protonated exposed epsilon-amino groups of lysine residues and with alpha-amino groups in human serum albumin and pancreatic ribonuclease A. The reaction of Schiff base formation proceeds within a wide pH range--from 3.0 to 12.0. At a great pyridoxal-5-phosphate excess in ribonuclease A in neutral or slightly acidic aqueous media all the ten epsilon-amino groups of lysine residues and the alpha-amino groups of Lys-1 become modified. The formation of aldimine bonds of pyridoxal-5-phosphate with protonated amino groups in acidic media is determined by ionization of its phenol hydroxyl and phosphate residues. Acetaldehyde, propionic aldehyde and pyridine aldehyde interact only with non-protonated amino groups of the proteins. The equilibrium constants of pyridoxal-5-phosphate and other aldehydes binding to proteins and amino acids were determined. The rate constants of Schiff base formation for pyridoxal-5-phosphates with some amino acids and primary sites of proteins for direct and reverse reactions were calculated.
mesh_terms: D000478:Alkylation; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002417:Cattle; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010179:Pancreas / Q000201:enzymology*; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D012259:Ribonuclease, Pancreatic / Q000378:metabolism*; D012545:Schiff Bases / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D000596:Amino Acids; D012545:Schiff Bases; D012709:Serum Albumin; D011732:Pyridoxal Phosphate; D012259:Ribonuclease, Pancreatic
vernacular_title: Vzaimodeĭstvie piridoksal'-5-fosfata s syvorotochnym al'buminom cheloveka i pankreaticheskoĭ ribonukleazoĭ.