期刊
JOURNAL OF PHYSICAL CHEMISTRY B
卷 113, 期 34, 页码 11754-11764出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp904249s
关键词
-
资金
- Institute of Biomedical Sciences, Academia Sinica
- NSC [NSC 9521 13-M-001-001]
Unnatural amino acid residues are increasingly being used in metalloprotein design and engineering to expand the repertoire of protein structures/folds and functions. However, natural but nonstandard amino acid residues (not in the basic set of 20) possessing metal-ligating groups such as selenocysteine (See), pyrrolysine (Pyl), and gamma-carboxyglutamic acid (Gla) have attracted little attention, and their potential as metal-binding entities in metalloprotein engineering has not been assessed. In particular, the metal-binding affinity/selectivity of these three rare residues remains unclear. Herein, the metal-binding affinity/selectivity of the Gla, Pyl, and See side chains have been systematically studied using a combined density functional theory and continuum dielectric method. The calculations reveal an advantage of using these noncanonical protein building blocks instead of the standard 20 amino acid residues, Gla(2-), Pyl(0), and Sec(-) have greater potential in trapping the metal cation than their standard amino acid counterparts. They prefer binding to Zn2+ rather than to Mg2+ or Ca2+ in a protein cavity due to the better electron-accepting ability and lower coordination number preference of Zn2+, as compared to Mg2+ and Ca2+. Between Ca2+. and Mg2+, Gla(2)- prefers Ca2+, whereas Pyl(0) and Sec(-) poorly discriminate between the two metal cations. The results herein Suggest that Gla(2-), Pyl(0) and Sec(-) could be employed as very efficient metal-binding entities in engineering metalloproteins with preprogrammed properties.
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