The pH Activity Relations of Two LDH Homotetramers From Trout Liver and Their Physiological Significance
- 1 July 1973
- journal article
- Published by Canadian Science Publishing in Journal of the Fisheries Research Board of Canada
- Vol. 30 (7) , 1023-1026
- https://doi.org/10.1139/f73-170
Abstract
The LDH homotetramers from the liver tissues of B″B″ and B′B′ steelhead trout phenotypes were each demonstrated to possess two pH optima, the usually described broad one spreading over 1.0 units in the alkaline region, and a new extremely narrow one spread over 0.128 units in the physiological range. The narrow pH optimum of LDH-B″4 in the lactate to pyruvate reaction exhibited an optimum at 7.302 and that of LDH-B′4 at 7.430. In the opposite reaction, LDH-B″4 and -B′4 passed through equally sharp minima at pH 7.331 and 7.428, respectively. At their respective narrow pH optima, LDH-B″4 exhibited a lactate conversion rate 3.6 times higher than that of LDH-B′4.The possible physiological significance of the narrow pH optima to poikilotherms and the differential lactate conversion rate to relative swimming endurance between the two phenotypes are discussed.Keywords
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