Stereochemistry of guanidine-metal interactions: implications for L-arginine-metal interactions in protein structure and function |
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Authors: | Di Costanzo Luigi Flores Lloyd V Christianson David W |
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Institution: | Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA. |
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Abstract: | The geometries of 150 guanidine-metal ion interactions retrieved from crystal structures deposited in the Cambridge Structural Database have been analyzed. Metal ions exhibit a preference for anti coordination stereochemistry in the plane of the unprotonated guanidine group, usually in chelate complexes with a diguanidine moiety, but syn-oriented interactions are occasionally found for single guanidine-metal interactions. Three L-arginine-metal coordination interactions are found in metalloenzyme structures deposited in the Protein Data Bank: biotin synthase from E. coli, His-67 --> Arg human carbonic anhydrase I, and inactivated B. caldovelox arginase complexed with L-arginine. In these proteins, L-arginine-metal coordination adopts syn/out-of-plane and anti/in-plane coordination stereochemistry. The implications of these results for L-arginine-metal interactions in protein structure and function are discussed. Although such interactions are rare, this analysis serves as a useful reference point for the growing interest in enzymes containing L-arginine residues that function as general bases or metal ligands. |
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Keywords: | amino acid metalloenzyme metal–ligand coordination crystal structure |
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