Cysteamine oxygenase

Figure 14.7. Pathways for the synthesis of taurine from cysteine. Cysteine sulfinate decarboxylase, EC 4.1.1.29 cysteic acid decarboxylase, EC 4.1.1.29 (glutamate decarboxylase, EC 4.1.1.15) cysteine oxidase, EC 1.13.11.20 cysteamine oxygenase, EC 1.13.11.19 and hypotaurine oxidase, EC 1.8.1.3. Relative molecular masses (Mr) cysteine, 121.2 cysteamine, 77.2 cysteine sulfinic acid, 153.2 cysteic acid, 169.2 hypotaurine, 109.1 and taurine, 125.1.

Cavallini, D., C. De Marco, R. Scandurra, S. Dupr, and M. T. Graziani The Enzymatic Oxidation of Cysteamine to Hypotaurine. J. Biol. Chem. 241, 3189 (1966). Rotilio, G., G. Frederici, L. Calabrese, M. Costa, and D. Cavallini An Electron Paramagnetic Resonance Study of the Nonheme Iron of Cysteamine Oxygenase. J. Biol. Chem. 245, 6235 (1970). 

X 10 s 38 = 1.8 X 10 s. Even in the absence of cooperative phenomena, 08 binding by hemocyanin involves a minimum of two elementary steps, and this finding might be correlated with the presence of two metal atoms in each site. Raman spectroscopy has been used to investigate the nature of the co-ordination of iron in clostridial rubredoxin, and e.s.r. and Mossbauer spectroscopy have been used to study the non-haem iron proteins cysteamine oxygenase and adrenodoxin. ... 

In this context it is important to examine the tissue levels of cysteine oxygenase and cysteamine oxygenase activities in order to distinguish, if possible, the relative contribution of CSA pathway and cysteamine pathway in TAU biosynthesis. 

Cysteamine oxygenase actl ty was determined as previously reported (30) with 2 jjmoles of S-cysteamine, in the presence or absence of 0.2 jjmoles of phenazine methosulfate as cofactor, with 100 umoles of phosphate buffer pH 7.6, in a final volume of 2 ml. After treatment with TCA aliquots were subjected to chromatography in Whatman n 4 paper strip by use of water-saturated phenol as solvent. Radioactivity was determined with a Packard 7201 radiochromatogram scanner and quantitative values were calculated by integration of radioactive peaks. 

Fig. 1 CYSTEAMINE OXYGENASE ACTIVITY IN HUMAN LIVER 30 mg of human liver homogenate, j> tained by biopsy, were incubated, as reported in the text, with S-cysteamine in the presence of cofactor. A = zero time, B = 4 hours incubation. The radioactive peaks correspond to taurine (l), hypotaurine (2) and unreacted cysteamine (3).

S-cysteamine, in the presence of phenazine methosulfate. After 4 hours incubation about 50% of cysteamine is oxidized to hypo-taurine and taurine. The same result is obtained if the activity is performed in the absense of phenazine. This result is unexpected since usually the activity in the presence of cofactor is between three or five times higher than in the absence. This particular aspect merit to be investigate further in order to examine whether a natural compound is present in human liver acting as cofactor for cysteamine oxygenase. Moreover, as shown in fig. 1, a consistent portion of hypotaurine is recovered oxidized to TAU. 

D. Cavallini, G. Federici, G. Ricci, S. Dupre, A. Antonucci and C. De Marco. The specificity of cysteamine oxygenase. FEBS-Let-ters, 1975, 56 348. 

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