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Báo cáo y học: "Direct electrochemical analyses of human cytochromes b5 with a mutated heme pocket showed a good correlation between their midpoint and half wave potentials"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học quốc tế cung cấp cho các bạn kiến thức về ngành y đề tài: Direct electrochemical analyses of human cytochromes b5 with a mutated heme pocket showed a good correlation between their midpoint and half wave potentials | Aono et al. Journal of Biomedical Science 2010 17 90 http www.jbiomedsci.eom content 17 1 90 tì.NSC The cost of publication in Journal of Biomedical Science Is borne by the National Science Council Taiwan JOURNAL OF BIOMEDICAL SCIENCE RESEARCH Open Access Direct electrochemical analyses of human cytochromes b5 with a mutated heme pocket showed a good correlation between their midpoint and half wave potentials -I- A 11 11 1 2 3 1 Tomomi Aono Yoichi Sakamoto Masahiro Miura Fusako Takeuchi Hiroshi Hori Motonari Tsubaki Abstract Background Cytochrome b5 performs central roles in various biological electron transfer reactions where difference in the redox potential of two reactant proteins provides the driving force. Redox potentials of cytochromes b5 span a very wide range of 400 mV in which surface charge and hydrophobicity around the heme moiety are proposed to have crucial roles based on previous site-directed mutagenesis analyses. Methods Effects of mutations at conserved hydrophobic amino acid residues consisting of the heme pocket of cytochrome b5 were analyzed by EPR and electrochemical methods. Cyclic voltammetry of the heme-binding domain of human cytochrome b5 HLMWb5 and its site-directed mutants was conducted using a gold electrode pre-treated with b-mercarptopropionic acid by inclusion of positively-charged poly-L-lysine. On the other hand static midpoint potentials were measured under a similar condition. Results Titration of HLMWb5 with poly-L-lysine indicated that half-wave potential up-shifted to -19.5 mV when the concentration reached to form a complex. On the other hand midpoint potentials of-3.2 and 16.5 mV were obtained for HLMWb5 in the absence and presence of poly-L-lysine respectively by a spectroscopic electrochemical titration suggesting that positive charges introduced by binding of poly-L-lysine around an exposed heme propionate resulted in a positive shift of the potential. Analyses on the five site-specific mutants showed a good correlation