Abstract
A correction of temperature coefficient for lactate dehydrogenase (LDH) activity against human sera from healthy, myocardial infarction and hepatitis patients, was discribed earlier2).
When pure forms of LDH isozyme, H4 or M4, were used as enzyme sources, it was the highest sensitivity by temperature variation of all samples in this work.
An Arrhenius plot of all samples gave two phase line that it was increased sharply from 25°to 37°C, and more slowly up to 40° as like as in previous report2), but the break occurs around 37°C. From these observation, it is pressumed that the enzyme molecule occurs a conformational change and a variation of heat stability depending upon pH change.
In other hand, percentage of subunits constitution calculated from the ratio of LDH activities using NAD in the presence of 450mM lactate and thionicotinamide hypoxanthine dinucleotide.(TNXD) in the presence of 15mM lactate were identical with that values calculated from enzymograms.
When percentage of subunits constitution was taken into account, it was postulated that the difference of temperature coefficient was reflecting the amount of its constitution precisely.
