... T., Yamazaki, K., Kyogoku, Y. &Kobayashi, Y. (1998) Solution structure of thermostable cyto-chrome c-552 from Hydrogenobacter thermophilus determined by1H-NMR spectroscopy. Biochemistry ... aheme covalently attached to the polypeptide chain via twothioether bonds, formed from the vinyl groups of the hemeand the two cysteine residues in the consensus Cys-X-X-Cys-His motif [1–4]. ... and Phe34 to Tyr/Glu43 to Tyr (F3 4Y/ E4 3Y) ] in the three regions of PA c-551 each individuallyenhanced the overall protein stability [8]. These studies,together with structure analysis, provided...