[Importance of the parameters of temperature and natural light on stability of 2 types of L(+) lactate:cytochrome oxidoreductases (cytochromes b2) extracted from Hansenula anomala yeast].

In this communication, we present the effect of two parameters, temperature and daylight-at high ionic strength-on the stability of H-flavocytochrome b2 solutions prepared using [H-flavocytochrome b2 (S) or not [H-flavocytochrome b2 (n) n-butanol during extraction. These two enzyme preparations presented the same behaviour towards these two parameters: in the dark, temperature was critical; in daylight, an opposite effect was observed for this parameter: the stability of samples was smaller at 0 degrees C. However, the evolution of life of the classical kinetic parameters (Km and Vm) of the enzymatic reaction is presented for three samples of H-flavocytochrome b2 (n) or (s) exposed to daylight at 20 +/- 0,1 degrees C.