N. Thoai, S. Zappacosta, Y. Robin
Nov 1, 1963
Citations
0
Influential Citations
13
Citations
Journal
Comparative Biochemistry and Physiology
Abstract
Abstract 1. 1. The biogenesis of taurocyamine (2-guanidoethane sulphonic acid) and hypotaurocyamine (2-guanidoethane sulphinic acid) was studied in the vertebrate ( Rattus sp.) and in the invertebrates ( Arenicola marina L. and Phascolosoma vulgare Blainville). 2. 2. The sulphur precursors of taurocyamine were investigated in rats and Arenicola after administration of 35 S-labelled compounds ( 35 S-cystine, 35 S-sulphite, 35 S-sulphate). Radiochromatographic study of urine (rats) or tissues ( Arenicola ) shows, in some experiments, the formation of radioactive taurine, hypotaurine and taurocyamine, but the results are not always reproducible; this fact could be explained by active exchange reactions between -SH, -SO 2 − , -SO 3 − groups, which are known to occur in living organisms. 3. 3. The incorporation of the amidino group of arginine in the taurocyamine and hypotaurocyamine molecules in Arenicola and Phascolosoma has been demonstrated through in vivo experiments using 14 C-amidino- dl -arginine and the mechanism of the reaction has been investigated. 4. 4. In worms and in all tissues studies, the specific radioactivity of hypotaurocyamine synthesized from 14 C-amidinoarginine is three to eighteen times higher than that of taurocyamine synthesized during the same experiments. This fact suggests that hypotaurocyamine is the natural precursor of taurocyamine, which would arise from the enzymic or non-enzymic oxidatin of the sulphinic guanido derivative. 5. 5. The specific radioactivity of hypotaurocyamine is found to be higher in viscera than in muscle, which indicates that this compound is synthesized in the viscera. 6. 6. In vitro studies with partially purified transamidinase of Phascolosoma vulgare have shown the formation of 14 C-hypotaurocyamine, but not of 14 C-taurocyamine, from 14 C-amidinoarginine; the specific radioactivity of hypotaurocyamine so synthesized is equal to that of the labelled arginine used in this study. This result confirms that hypotaurocyamine is formed from arginine through transamidination reactions and without any detectable intermediates. 7. 7. In conclusion, hypotaurocyamine seems to be synthesized through transamidination reaction between arginine and the corresponding amino derivative, according to the general process demonstrated in vertebrate and invertebrate organisms for the biosynthesis of the naturally occuring guanido derivatives. On the other hand, taurocyamine does not seem to proceed from enzymic transamidination between arginine and taurine, but from oxidation of hypotaurocyamine, as already demonstrated for the formation of taurine from hypotaurine. 8. 8. Some data are presented on the quantitative distribution of taurocyamine and hypotaurocyamine in Arenicola and Phascolosoma tissues.