Hypotaurine oxidation

Table I. Effects of certain cofactors on hypotaurine oxidation by homogenates from developing mice...

The oxidation rate was also dependent on the concentration of hypotaurine in the incubation medium. The reaction appeared to obey simple Michaelis-Menten kinetics (Fig. 2). The kinetic constants were estimated from a linear transformation of the Michaelis-Menten equation in a t against v/s plot. The apparent Michaelis constant ( ) was about 0.2 ramol/1 and the maximal velocity (F) about 0.1 ymol/s X kg. In our crude liver homogenate the apparent for hypotaurine oxidation was of the same order of magnitude as for the partially purified L-cysteine sulphinate decarboxylase (Jacobsen et al., 1964), the preceding enz3nne in the biosynthesis pathway. 

Table V. Subcellular distribution of hypotaurine oxidation in 7-day-old mice...

The pH dependence curve of the oxidation reaction was rather flat-topped (Fig. 3). The pH optimum was about 9.0. In all previous studies on hypotaurine oxidation the pH of the incubation mixture has been adjusted to 7.4-7.8 (Cavallini et al., 1954 Sumizu, 1962 Oja et al., 1973 Di Giorgio et al., 1977). In contrast to the present results Di Giorgio et al. (1978) reported a pH optimum of 7.0 for hypotaurine oxidation in the retina. The too acidic pHs tested may account for the frequent difficulties in... 

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