Analyzing the selectivity and successiveness of a two-electron capture on a multiply disulfide-linked protein
In: Journal of Chemical Theory and Computation (JCTC, 2015
Online
academicJournal
Zugriff:
Hybrid QM/MM calculations were performed on a circular macropeptide (kalata B1, PDB ID 1NB1) containing three disulfide linkages, to evaluate their respective reactivities toward (gas-phase) electron valence-attachment of one and two electron(s). The three disulfide bonds -CH2-S-S-CH2- were simultaneously described at the MP2/6-31+G**(S),6-31G*(C,H) level of theory, and the remaining of the 29 residues of kalata B1 were described by the CHARMM27 force field. The one-electron addition is favored on the linkage between cysteine residues 1 and 15, Cys(1 -15), by ca. 1 eV over the two other disulfide linkages. The decomposition of the overall effect into geometrical and electrostatic contributions evidence (i) the key role of an arginine (R24) and (ii) a weaker geometrical penalty for elongating the nonstructural Cys(1 -15) linkage. The addition of a second electron leads to the formation of the dithiolate Cys(1,15), favored by more than 1 eV over other adducts (either dithiolates or diradical dianionic species). This can be traced back to a structural reorganization, with a flip of R24 side chain. Its positively charged extremity points almost equidistantly toward one thiolate -CH2-S-, hence stabilizing this dianion.
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Analyzing the selectivity and successiveness of a two-electron capture on a multiply disulfide-linked protein
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Autor/in / Beteiligte Person: | Dumont, Elise ; Laurent, Adele D ; Loos, Pierre-Francois ; Assfeld, Xavier |
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Zeitschrift: | Journal of Chemical Theory and Computation (JCTC, 2015 |
Veröffentlichung: | American Chemical Society, 2015 |
Medientyp: | academicJournal |
ISSN: | 1549-9618 (print) |
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