The effect of temperature on enzymes used in diagnostics

Abstract

A number of enzymes that are used in clinical analysis have been studied in relation to the effect of temperature on their activity. Both V max and K m were determined over a temperature range from 13 to 55°C. Whereas V max values increased steadily until denaturation point with all enzymes, the effect of temperature on K m was more variable. With most enzymes there was a gradual increase in K m, often with a sharp rise close to the denaturation temperature. In most cases, K m did not increase as fast as V max consequently the enzyme efficiency, V max K m , also increased slightly with temperature. However this was not the case with rabbit muscle lactate dehydrogenase, for which the K m for pyruvate increased faster than V max. As a consequence, it was predicted and confirmed that enzymatic analysis of pyruvate using lactate dehydrogenase is more rapid at 20°C than at 35°C or 50°C.