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Solution Structure and Acid‐Base Properties of Reduced α‐Conotoxin MI
Author(s) -
Faragó Zoltán,
Mirzahosseini Arash,
Horváth Dániel,
Pálla Tamás,
Horváth Péter,
Perczel András,
Noszál Béla
Publication year - 2021
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.202100464
Subject(s) - protonation , chemistry , peptide , cysteine , titration , stereochemistry , amino acid , folding (dsp implementation) , reactivity (psychology) , crystallography , organic chemistry , biochemistry , ion , enzyme , medicine , alternative medicine , pathology , electrical engineering , engineering
The reduced derivative of α‐conotoxin MI, a 14 amino acid peptide is characterized by NMR‐pH titrations and molecular dynamics simulations to determine the protonation constants of the nine basic moieties, including four cysteine thiolates, and the charge‐dependent structural properties. The peptide conformation at various protonation states was determined. The results show that the disulfide motifs in the native globular α‐conotoxin MI occur between those cysteine moieties that exhibit the most similar thiolate basicities. Since the basicity of thiolates correlates to its redox potential, this phenomenon can be explained by the higher reactivity of the two thiolates with higher basicities. The folding of the oxidized peptide is further facilitated by the loop‐like structure of the reduced form, which brings the thiolate groups into sufficient proximity. The 9 group‐specific protonation constants and the related, charge‐dependent, species‐specific peptide structures are presented.