Purification and kinetic characteristics of strombine dehydrogenase from the foot muscle of the hard clam (Meretrix lusoria).
Strombine dehydrogenase (SDH, EC 1.5.1.22) from the foot of the hard clam Meretrix lusoria was purified over 470-fold to apparent homogeneity. It has a monomeric structure with a relative molecular mass of 46,000. Two isoenzymes were identified with isoelectric points of 6.83 and 6.88. SDH is heat labile, and has pH and temperature optima of 7.4-7.6 and 45-46°C, respectively. l-Alanine, glycine, and pyruvate are the preferred substrates. l-Serine is the third preferred amino acid. Iminodiacetate with the lowest K(i) of SDH at both pH 6.5 and 7.5 was the strongest inhibitor among succinate, acetate, iminodiacetate, oxaloacetate, and l-/d-lactate. The inhibitory activities of succinate at pH 6.5, and iminodiacetate and oxaloacetate at pH 7.5 on the SDH were higher. These inhibitors are either competitive or mixed-competitive inhibitors. Half of the enzymatic activity of SDH was inhibited by 0.2mM Fe(3+) and 0.6mM Zn(2+).
Lee
An-Chin
AC
Department of Aquatic Biosciences, College of Life Science, National Chiayi University, Chiayi 600, Taiwan. aclee@mail.ncyu.edu.tw
Lee
Kuen-Tsung
KT
Pan
Li-Ying
LY
D000085:Acetates / Q000494:pharmacology; D000818:Animals; D049872:Bivalvia / Q000033:anatomy & histology* / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D019344:Lactic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D009132:Muscles / Q000201:enzymology*; D010071:Oxaloacetates / Q000494:pharmacology; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D019802:Succinic Acid / Q000494:pharmacology; D013696:Temperature
D000085:Acetates; D010071:Oxaloacetates; D019344:Lactic Acid; D019802:Succinic Acid; D000587:Oxidoreductases Acting on CH-NH Group Donors; C036085:strombine dehydrogenase