Lactate dehydrogenase (LD or LDH, EC1.1.1.27) is a type of NAD-dependent kinase with three subunits: LDHA, LDHB, and LDHC, which can constitute 6 kinds of tetrameric isoenzymes. Animal lactate dehydrogenase is a tetramer composed of 4 subunits. The common A and B subunits consist of 5 LDH isozymes (LDH1-5), and the C subunit only forms one LDH isozyme. The enzyme is LDH-C4.
Lactate dehydrogenase is a metalloprotein containing zinc ions with a molecular weight of 135-140kD. It is one of the important enzyme systems for anaerobic glycolysis and gluconeogenesis. It can catalyze the reduction and oxidation reactions between propionic acid and L-lactic acid , Can also catalyze related α-keto acids. LDH is widely present in human tissues, with the highest content in the kidney, followed by myocardium and skeletal muscle. LDH in red blood cells is about 100 times that of normal serum.
1. Classification of lactate dehydrogenase
1. According to different binding coenzymes, microorganisms generally contain two lactate dehydrogenases, NAD-dependent lactate dehydrogenases (NAD-dependent lactate dehydrogenases, nLDHs) and NAD-independent lactate dehydrogenases (NAD-independent lactate dehydrogenases). Lactate dehydrogenases, iLDHs) two categories.
2. According to the different configuration of its catalytic substrate, NAD-dependent lactate dehydrogenase can be divided into NAD-dependent-L-lactate dehydrogenase (L-NAD-dependent lactate dehydrogenase) and NAD-dependent- D-lactate dehydrogenase (D-NAD-dependent lactate dehydrogenase) two major categories, respectively catalyze the synthesis of pyruvate into L-lactic acid and D-lactic acid.
3. According to the different natural electron acceptors, NAD-independent lactate dehydrogenase can be divided into three categories. The first type is membrane protein, which uses membrane quinones as the external electron acceptor; the second type directly uses O2 as the electron acceptor. According to the different oxidation end products, it is subdivided into lactate oxidase (LOX). ) And lactate monooxygenases (Lactate monooxygenases, LMO), the former produces pyruvate and H2O2, while the latter produces acetic acid, CO2 and H2O; the third type is thiamine b2 (flavocytochrome b2), which exists in fungi, it The natural electron acceptor is cytochrome c.
2. Structure and function of lactate dehydrogenase
Studies have shown that L-lactate dehydrogenase (L-LDH) and L-malate dehydrogenase belong to the same family, while D-lactate dehydrogenase (D-LDH) belongs to the D-2-hydroxy acid dehydrogenase family.
1. D-lactate dehydrogenase: most D-lactate dehydrogenase catalyzes a reversible reaction, and a few are irreversible; for reversible D-lactate dehydrogenase, the reverse reaction is only catalyzed when the concentration of lactic acid in the environment is high. That is to catalyze the synthesis of pyruvate from lactic acid to participate in the metabolism of bacteria.
2. L-lactate dehydrogenase: In most lactic acid bacteria, there are not only D-lactate dehydrogenase but also L-lactate dehydrogenase. L-lactate dehydrogenase catalyzes the reduction of pyruvate to L-lactic acid.
three,乳酸脱氢酶检测工具
The most common detection tool for lactate dehydrogenase (LDH) is of course the LDH kit cytotoxicity detection kit. Abbkine Lactate Dehydrogenase Cytotoxicity Detection Kit (#KTA1030) provides a simple and convenient colorimetric method for cytotoxicity research.
Kit components: experimental buffer, lactic acid solution, MTT solution, PES solution, LDH positive control, NAD+ solution, Triton X-100 (10%)
Features & advantages:
1. Analyze the effects of compounds or environmental factors on cell death.
2. LDH is released from the cells into the culture medium, forming a visual color response.
3. Detection range: 10,00-100,0000 cells/well.
Lactate dehydrogenase cytotoxicity test kit link:
http://www.abbkine.cn/product/KTA1030