Economy in Protein Design: Evolution of a Metal-Independent 
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- 作者：Mary D. Struthers ; Richard P. Cheng ; and Barbara Imperiali
- 刊名：Journal of the American Chemical Society
- 出版年：1996
- 出版时间：April 3, 1996
- 年：1996
- 卷：118
- 期：13
- 页码：3073 - 3081
- 全文大小：260K
- 年卷期：v.118,no.13(April 3, 1996)
- ISSN：1520-5126
文摘
An iterative design process involving the synthesis andstructural analyses of five polypeptides patternedafter the zinc finger domains is described. This process has ledto the development of a metal-independent folded
motif, BBA1. In contrast to the zinc fingersand other naturally occurring peptides of similar size, thissmallmonomeric structure folds without the assistance of metal cationligation or disulfide bridges. To probe the effectof metal binding on the secondary and tertiary structure of peptidesthroughout the design process, a non-standardamino acid 3-(1,10-phenanthrol-2-yl)-L-alanine (Fen)was incorporated and its unique chromophore utilized forcirculardichroism (CD) analysis. Advanced designs were analyzed by both CDand 2D NMR. The solution structure ofBBA1 was determined using NOE restrained simulatedannealing. The average RMSD for the backbone atoms ofresidues 1-22 is 0.9 ± 0.3 Å. Analysis of the resultingstructure reveals that the -helix and -hairpin areassociatedvia a well-defined hydrophobic core including several keyhydrophobic residues. A key design feature of BBA1isthe utilization of a type II' reverse turn to promote -hairpinformation; a control peptide, in which the -turn ofBBA1 was changed from a type II' to a type II, lackstertiary structure. Thus the effects of the turn type onthethree-dimensional structure of this motif are dramatic.BBA1, a 23-residue mixed / motif, defines a newlowerlimit for the size of an independently folded polypeptide with nativestructure.
motif, BBA1. In contrast to the zinc fingersand other naturally occurring peptides of similar size, thissmallmonomeric structure folds without the assistance of metal cationligation or disulfide bridges. To probe the effectof metal binding on the secondary and tertiary structure of peptidesthroughout the design process, a non-standardamino acid 3-(1,10-phenanthrol-2-yl)-L-alanine (Fen)was incorporated and its unique chromophore utilized forcirculardichroism (CD) analysis. Advanced designs were analyzed by both CDand 2D NMR. The solution structure ofBBA1 was determined using NOE restrained simulatedannealing. The average RMSD for the backbone atoms ofresidues 1-22 is 0.9 ± 0.3 Å. Analysis of the resultingstructure reveals that the -helix and -hairpin areassociatedvia a well-defined hydrophobic core including several keyhydrophobic residues. A key design feature of BBA1isthe utilization of a type II' reverse turn to promote -hairpinformation; a control peptide, in which the -turn ofBBA1 was changed from a type II' to a type II, lackstertiary structure. Thus the effects of the turn type onthethree-dimensional structure of this motif are dramatic.BBA1, a 23-residue mixed / motif, defines a newlowerlimit for the size of an independently folded polypeptide with nativestructure.