title: Properties of lactate dehydrogenase from the isopod, Saduria entomon.
abstract: Saduria entomon lactate dehydrogenase (LDH-A4*) from thorax muscle was purified about 89 fold to specific activity 510 micromol NADH/min/mg using Cibacron Blue 3GA Agarose and Oxamate-Agarose chromatographies. The enzyme is a tetramer, with molecular weight of 140 kDa for the native enzyme and 36 kDa for the subunit. The isoelectric point was at pH 5.7. The enzyme possesses high heat stability (T50 = 71.5 degrees C). The optimum pH for pyruvate reduction reaction was 6.5, while for lactate oxidation one, the maximum activity was at pH 9.1. The Km for pyruvate was minimal at 5 degrees C, the average environmental temperature of the isopod. The Km values determined at 30 degrees C and optimal pH for pyruvate reduction and lactate oxidation were 0.18 and 90.04 mM, respectively. Amino acid compositional analyses showed the strongest resemblance of the isopod isoenzyme to cod (Gadus morhua) LDH-C4.
authors.affiliation: Gdańsk University Biological Station, Gdańsk-Sobieszewo, Poland.
authors.forename: E
authors.initials: E
authors.lastname: Mulkiewicz
authors.forename: M S
authors.initials: MS
authors.lastname: Zietara
authors.forename: K
authors.initials: K
authors.lastname: Stachowiak
authors.forename: E F
authors.initials: EF
authors.lastname: Skorkowski
mesh_terms: D000818:Animals; D003445:Crustacea / Q000201:enzymology*; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007770:L-Lactate Dehydrogenase / Q000032:analysis* / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D007770:L-Lactate Dehydrogenase