caa a22 4500 465729517 CHVBK 20180323111737.0 cr unu---uuuuu 170327e19901001xx s 000 0 eng 10.1007/BF02040305 doi (NATIONALLICENCE)springer-10.1007/BF02040305 Effect of gamma-radiation on Methanosarcina hydrogenase containing transition metal ions [Elektronische Daten] [H. Arnikar, S. Bhosale, D. Kshirsagar, A. Kapadi, T. Yeole] Tracer studies using65Zn and58Co showed that of the four forms ofMethanosarcina hydrogenases, the A form has about 15% of acid labile zinc, while the hydrogenase D has about 50% of cobalt of the total bound activity in the cell and the other two forms B and C have neither zinc nor cobalt. However, all hydrogenases are known to contain iron, sulfur and probably nickel in trace amounts. All air-oxidized forms of hydrogenases catalyze the reduction of methyl viologen after a finite incubation period. The reduction is revealed by an increase in the absorption peak at 602 nm. On γ-irradiation, all the four hydrogenases changed to more stable oxidized forms, as indicated by an increase in the optical absorption in the visible region at 405 nm. The irradiated samples showed a greater time lag before they could reduce methyl viologen, the time lag increasing with the γ-dose. The irradiated enzymes could be reactivated by flushing with H2. The zinc-bearing hydrogenase A alone appeared to be immune to γ-radiation in its ability to reduce methyl viologen. This may be due to the zinc having no unpaired electrons to interact with γ-radiation or the primary radiolytic products. Akadémiai Kiadó, 1990 Arnikar H. M.A.C.S. Research Institute, 411 004, Pune, (India) aut Bhosale S. M.A.C.S. Research Institute, 411 004, Pune, (India) aut Kshirsagar D. M.A.C.S. Research Institute, 411 004, Pune, (India) aut Kapadi A. M.A.C.S. Research Institute, 411 004, Pune, (India) aut Yeole T. M.A.C.S. Research Institute, 411 004, Pune, (India) aut Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 142/2(1990-10-01), 349-358 0236-5731 142:2<349 1990 142 10967 https://doi.org/10.1007/BF02040305 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02040305 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Arnikar H. M.A.C.S. Research Institute, 411 004, Pune, (India) aut NATIONALLICENCE 700 1- Bhosale S. M.A.C.S. Research Institute, 411 004, Pune, (India) aut NATIONALLICENCE 700 1- Kshirsagar D. M.A.C.S. Research Institute, 411 004, Pune, (India) aut NATIONALLICENCE 700 1- Kapadi A. M.A.C.S. Research Institute, 411 004, Pune, (India) aut NATIONALLICENCE 700 1- Yeole T. M.A.C.S. Research Institute, 411 004, Pune, (India) aut NATIONALLICENCE 773 0- Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 142/2(1990-10-01), 349-358 0236-5731 142:2<349 1990 142 10967 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer