Lactate Dehydrogenase Isozymes: Substrate Inhibition in Various Human Tissues

See allHide authors and affiliations

Science  17 Dec 1965:
Vol. 150, Issue 3703, pp. 1590-1593
DOI: 10.1126/science.150.3703.1590


The total lactate dehydrogenase (LDH) in whole homogenates of various human tissues reacts more similarly toward pyruvate and lactate at 25°C than expected from the marked differences in substrate inhibition at this temperature between isolated, purified LDH-1, and LDH-5. At 37°C, LDH-5 closely resembles LDH-1 in extent of inhibition by substrate. These results are incompatible with the theory that differences in degree of isozyme inhibition by substrate have resulted in predominance of LDH-5 in aerobic tissues and predominance of LDH-1 in aerobic tissues.