The pyridoxal- and pyridoxal 5'-phosphate-catalysed non-enzymic degradations of l-serine o-sulphate and related compounds.
1. l-Serine O-sulphate and l-threonine O-sulphate are degraded in the presence of pyridoxal 5'-phosphate to yield equimolar amounts of the corresponding keto acid, ammonia and sulphate. 2. Pyridoxal catalyses the same reactions at a faster rate. 3. One of a number of bi- or ter-valent metal ions must be present for these degradations to proceed. The reaction rates are dependent on a number of factors including pH and the nature of the metal ion used. 4. Studies with related sulphate esters indicate that the alpha-hydrogen atom and the amino group are essential for activity. 5. Spectral changes during the pyridoxal and pyridoxal 5'-phosphate catalysis of l-serine O-sulphate breakdown suggest the formation of a Schiff base. 6. The mechanism for these reactions appears to be in accordance with the general mechanism proposed for pyridoxal-catalysed alphabeta-elimination reactions.
D000535:Aluminum; D000641:Ammonia; D002384:Catalysis; D003300:Copper; D005708:Gallium; D006863:Hydrogen-Ion Concentration; D007651:Keto Acids; D000432:Methanol; D010847:Picolines; D011732:Pyridoxal Phosphate; D012694:Serine; D013431:Sulfates; D013912:Threonine
D007651:Keto Acids; D010847:Picolines; D013431:Sulfates; D013912:Threonine; D012694:Serine; D011732:Pyridoxal Phosphate; D000641:Ammonia; D003300:Copper; D005708:Gallium; D000535:Aluminum; D000432:Methanol