S- cysteamine

Grachev SA, Kropachev EV, Litvyakova Gl (1983) Synthesis of 5-S-cysteamine-6-hydroxythymine and evidence of its formation in the y radiolysis of aqueous solutions of thymine and cyste-amine. Bull Acad Sci USSR, Chem Ser (Engl Trans) 1595-1600 Grachev SA, Kropachev EV, Litvyakova Gl (1986) Addition of cysteamine to thymine and thymidine monophosphate initiated by y-irradiation. Bull Acad Sci USSR, Chem Ser (Engl Trans) 10 2178-2184... 

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. 

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