ORGAN SPECIFICITY AND LACTATE-DEHYDROGENASE ACTIVITY. DIFFERENTIAL INHIBITION BY UREA AND RELATED COMPOUNDS

1. The effect of urea on the lactate-dehydrogenase activities of human-heart and -liver tissue extracts and on crystalline ox-heart and rabbit-muscle enzyme have been determined. Similar studies on electrophoretically separated isoenzyme fractions have shown an inverse relationship between sensitivi...

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Bibliographic Details
Published in:Biochemical journal 1965-02, Vol.94 (2), p.384-389
Main Authors: WITHYCOMBE, W A, PLUMMER, D T, WILKINSON, J H
Format: Article
Language:English
Subjects:
Animals
Butyrates
Carbamates
Cyanates
Enzyme Inhibitors
Humans
Isoenzymes
Keto Acids
L-Lactate Dehydrogenase
Lactates
Liver - enzymology
Muscles
Myocardium
Old Medline
Organ Specificity
Oxidation-Reduction
Pyruvates
Rabbits
Spectrophotometry
Tissue Extracts
Urea
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Summary:1. The effect of urea on the lactate-dehydrogenase activities of human-heart and -liver tissue extracts and on crystalline ox-heart and rabbit-muscle enzyme have been determined. Similar studies on electrophoretically separated isoenzyme fractions have shown an inverse relationship between sensitivity to urea inhibition and electrophoretic mobility. 2. With pyruvate as substrate a sharp change in the nature of the inhibition of tissue lactate dehydrogenase with increasing concentrations of urea occurs at 1 m or 4 m with the electrophoretically slow and fast isoenzymes respectively. 3. At concentrations of urea less than 1 m, inhibition of the purified enzymes is competitive with respect to pyruvate and 2-oxobutyrate. 4. Similar studies have been carried out with methylurea and hydantoic acid, both of which are more potent inhibitors than urea.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj0940384