title: Effect of pyridoxal 5'-phosphate on Ca2+-stimulated adenosine triphosphatase activity in microsomes of rat submandibular gland in vitro.
abstract: 1. The Ca2+-ATPase activity in microsomes of rat submandibular gland was inhibited by pyridoxal 5'-phosphate in vitro. 2. The dissociation constant of the enzyme-pyridoxal 5'-phosphate complex was estimated to be 6.5 mM. 3. The inhibition of pyridoxal 5'-phosphate for both ATP and Ca2+ was competitive. 4. The order of inhibitory effectiveness of pyridoxal 5'-phosphate analogs was pyridoxal 5'-phosphate greater than pyridoxal HCl greater than pyridoxamine 5'-phosphate greater than pyridoxamine HCl. 5. The enzyme-pyridoxal 5'-phosphate complex was nonreducible with sodium borohydride.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D008861:Microsomes / Q000201:enzymology*; D010084:Oxidation-Reduction; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D051381:Rats; D013363:Submandibular Gland / Q000201:enzymology*
chemical_list: D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases