title: Aldolase and actin protect rabbit muscle lactate dehydrogenase from ascorbate inhibition.
abstract: Muscle-type LDH (LDH-m4) activity is critical for efficient anaerobic glycolysis. The results here show that rabbit LDH-M4 is inhibited by concentrations of ascorbate normally found in tissues. Aldolase and muscle G-actin were found to protect and to reverse inhibitions of LDH-m4 by ascorbate. G-actins showed some species specificity. Myosin, tropomyosin and troponin from rabbit muscle and muscle proteins from other animal sources had no affect on the inhibitions by ascorbate. The substrate inhibition of LDH-m4 by pyruvate is partially relieved by the presence of aldolase and lowers the Km without affecting the Vm. G-actin under similar conditions has no affect. It is believed that these studies reflect some of the resting properties of glycolytic enzymes that bind and unbind to contractile elements. It is proposed that ascorbate facilitates the storage of glycogen in muscle at rest by inhibiting glycolysis.
authors.affiliation: Department of Biology, University of California 0690, San Diego, La Jolla, CA 92093-0690, USA. prussell@ucsd.edu
authors.forename: Percy J
authors.initials: PJ
authors.lastname: Russell
authors.forename: Anita
authors.initials: A
authors.lastname: Williams
authors.forename: Xavier
authors.initials: X
authors.lastname: Amador
authors.forename: Reynaldo
authors.initials: R
authors.lastname: Vargas
mesh_terms: D000199:Actins / Q000494:pharmacology*; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005634:Fructose-Bisphosphate Aldolase / Q000494:pharmacology*; D006019:Glycolysis; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects* / Q000201:enzymology; D009218:Myosins / Q000378:metabolism; D020011:Protective Agents / Q000494:pharmacology; D019289:Pyruvic Acid / Q000378:metabolism; D011817:Rabbits; D014335:Tropomyosin / Q000378:metabolism; D014336:Troponin / Q000378:metabolism
chemical_list: D000199:Actins; D004791:Enzyme Inhibitors; D020011:Protective Agents; D014335:Tropomyosin; D014336:Troponin; D019289:Pyruvic Acid; D007770:L-Lactate Dehydrogenase; D009218:Myosins; D005634:Fructose-Bisphosphate Aldolase; D001205:Ascorbic Acid