Evidence for the role of vitamin C-6 as a cofactor of lysyl oxidase.
At 24 h after injection of 16-day chick embryos with [C-3H]pyridoxine hydrochloride, some of this label appears in the epiphysial cartilage. Over 35% of this radioactivity appears in the form of [G-3H]pyridoxal and a further 30% as other vitamin B-6 compounds. Partial purification of lysyl oxidase from the labelled epiphysial cartilage reveals a single peak of radioactivity coinciding with a single peak of enzyme activity. On dialysis against phosphate-buffered saline, 75% of this radioactivity is found to be non-diffusible. After incubation with isonicotinic acid hydrazide, a carbonyl reagent that appears to inhibit lysyl oxidase both in vivo and in vitro, a further 70% of the radioactivity is lost, with a roughly corresponding loss of enzyme activity. It is suggested that a form of vitamin B-6 is required as a cofactor of lysyl oxidase, and that this may have important implications in terms of connective-tissue metabolism.
D000594:Amino Acid Oxidoreductases / Q000378:metabolism*; D000818:Animals; D002356:Cartilage / Q000201:enzymology*; D002642:Chick Embryo; D002852:Chromatography, Ion Exchange; D007538:Isoniazid / Q000494:pharmacology; D008249:Protein-Lysine 6-Oxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011736:Pyridoxine / Q000378:metabolism*
D000594:Amino Acid Oxidoreductases; D008249:Protein-Lysine 6-Oxidase; D011736:Pyridoxine; D007538:Isoniazid