Lactic Dehydrogenase


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lactic dehydrogenase

[′lak·tik dē′hī·drə·jə‚nās]
(biochemistry)
An enzyme that catalyzes the dehydrogenation ofL-lactic acid to pyruvic acid. Abbreviated LDH.

Lactic Dehydrogenase

 

an enzyme of the oxidoreductase class; it catalyzes the reversible reduction of pyruvic acid to L-lactic acid with the participation of reduced nicotinamide adenine dinucleotide (NAD·H + H+) as a coenzyme:

Lactic dehydrogenase, extracted from the muscle tissue of vertebrates in crystalline form, is composed of four polypeptide sub-units (the molecular weight of one lactic dehydrogenase tetramer is 140,000). The equilibrium of the catalyzed lactic dehydrogenase reaction is strongly shifted toward the formation of lactic acid. The reaction requires the presence of NAD·H + H+ and proceeds in most animal tissues under anaerobic conditions. Cancer cells form one exception since a large amount of lactic acid is formed in these cells under aerobic conditions. Five isoenzymes of lactic dehydrogenase are known, which differ in amino acid composition as well as in certain physical, immunological, and catalytic properties. The determination of lactic dehydrogenase activity in blood plasma is of significant diagnostic value. Lactic dehydrogenase has been detected in Lactobacillaceae that catalyze the formation of D-lactic acid with the participation of reduced NAD.

IU. N. LEIKIN

References in periodicals archive ?
Serum creatine phosphokinase (CPK) and serum lactic dehydrogenase (LDH) levels were measured only on cases in 2005.
Her serum amylase level was elevated 1684 IU (normal 28-100), lactic dehydrogenase levels were also elevated 278 IU (normal 62-155 IU).
The serum lactic dehydrogenase (LDH) level was 1,164 U/L (normal: 240-480 U/L), and the serum creatine phosphokinase (CPK) level was 70 U/L (normal [less than or equal to] 167 U/L).
WORK-UP: His erythrocyte sedimentation rate was over 130 mm/h (normal range, 1-15 mm/h), lactic dehydrogenase was 311 U/L (normal range, 118-273 U/L), and C-reactive protein was 21.
The white blood cell count was 70,000 per [micro]L and the lactic dehydrogenase level was 12 000 U/L.
Among the assessed biochemical parameters, lactic dehydrogenase was consistently elevated, with an average value of 5162.
Laboratory studies showed an elevation of lactic dehydrogenase (1,403 IU/L; normal 180-460 IU/L), ferritin (12,727.
On the 11th day, he is transported to the pediatric ICU, where the following abnormalities are noted: metabolic acidosis with compensatory tachypnea; hyponatremia; increased creatine levels, total bilirubin levels, and lactic dehydrogenase levels; decreased albumin levels; high triglyceride levels; and neutropenia with an absolute neutrophil count of 0.
5 mg/dL, lactic dehydrogenase 2,066 U/L, total cholesterol 100 mg/dL, HDL-cholesterol 22 mg/dL, triglyceride 285 mg/dL, and ferritin 20,000 [micro] g/L.