Download MendeleyFormation of Cys-heme cross-link in K42C myoglobin under reductive conditions with molecular oxygen
Cheng, H.M., Yuan, H., Wang, X.J., Xu, J.K., Gao, S.Q., Wen, G.B., Tan, X., Lin, Y.W.(2018) J Inorg Biochem 182: 141-149
- PubMed: 29477977 Search on PubMed
- DOI: https://doi.org/10.1016/j.jinorgbio.2018.02.011
- Primary Citation Related Structures:
5YZF - PubMed Abstract:
The structure and function of heme proteins are regulated by diverse post-translational modifications including heme-protein cross-links, with the underlying mechanisms not well understood. In this study, we introduced a Cys (K42C) close to the heme 4-vinyl group in sperm whale myoglobin (Mb) and solved its X-ray crystal structure. Interestingly, we found that K42C Mb can partially form a Cys-heme cross-link (termed K42C Mb-X) under dithiothreitol-induced reductive conditions in presence of O 2 , as suggested by guanidine hydrochloride-induced unfolding and heme extraction studies. Mass spectrometry (MS) studies, together with trypsin digestion studies, further indicated that a thioether bond is formed between Cys42 and the heme 4-vinyl group with an additional mass of 16 Da, likely due to hydroxylation of the α‑carbon. We then proposed a plausible mechanism for the formation of the novel Cys-heme cross-link based on MS, kinetic UV-vis and electron paramagnetic resonance (EPR) studies. Moreover, the Cys-heme cross-link was shown to fine-tune the protein reactivity toward activation of H 2 O 2 . This study provides valuable insights into the post-translational modification of heme proteins, and also suggests that the Cys-heme cross-link can be induced to form in vitro, making it useful for design of new heme proteins with a non-dissociable heme and improved functions.
- School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China.
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