Chemical Properties
Off-white lyophilized powder or crystalline suspension of 3.2 mol/L ammonium sulfate, soluble in water, pI of 4.6, optimum pH 6.0.Stability: crystalline enzyme solution can be stored for 6-8 weeks with unchanged activity, sulfate suspension can be stabilized for more than a year, very dilute solution is unstable; optimum temperature of 39 ℃, rapid inactivation of temperatures above 60 ℃. Inhibitors are excess pyruvate, excess NAD, oxalic acid, oxalic acid monoamide, hydroxymalonic acid, malonic acid, urea, Cu2+, Hg2+, Ag+, 4-chloromercuric benzoic acid, pyrophosphoric acid or phosphate buffer and non-competitive inhibitors formed from coenzyme I (NAD) in alkaline inhibit oxidation reaction, excess lactate and non-competitive inhibitors formed from reduced coenzyme I (NADH) inhibit reduction reaction. inhibitors inhibit the reduction reaction; activators are 2-amino-2-methyl-1-propanol, fluoride, diethanolamine, and heparin (oxidizing). Enzymatic reaction: pyruvate + reduced coenzyme I + H+ ═ lactate + coenzyme I.
Uses
L-Lactic Dehydrogenase from bovine heart has been used as a standard in cytotoxicity assay. It has also been used in glutamic pyruvic transaminase (GPT) assay.
Uses
L-Lactic Dehydrogenase from bovine heart has been used in ATPase assay of R2 complex Rvb1p-Rvb2p, RecA protein and sarcoplasmic reticulum Ca
2+-ATPase (SERCA).
Uses
L-Lactic dehydrogenase is used in the determination of pyruvate (used in conjunction with reduced coenzyme) and in the diagnosis of myocardial infarction and leukemia.
General Description
L-lactate dehydrogenase (LDH) is an enzyme that catalyzes the conversion of lactate to pyruvate.In particular, lactic dehydrogenase A (LDHA) is mainly found in skeletal muscle, and for that reason is known as the M subunit. This recombinant form of LDHA has a C-terminal histidine-tag.
The gene LDHA (L-lactate dehydrogenase A chain) is mapped to human chromosome 11p15. It is a subunit of lactate dehydrogenase.
Biochem/physiol Actions
Also catalyzes the oxidation of other L-2-hydroxymonocarboxylic acids.
Purification Methods
A forty-fold purification of the dehydrogenase is effected by affinity chromatography using Sepharose 4B coupled to 8-(6-aminohexyl)amino-5'-AMP or -NAD . [Lees et al. Arch Biochem Biophys 163 561 1974, Pesce et al. J Biol Chem 239 1753 1964.]
