title: Stereochemistry of guanidine-metal interactions: implications for L-arginine-metal interactions in protein structure and function.
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.
authors.affiliation: Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.
authors.forename: Luigi
authors.initials: L
authors.lastname: Di Costanzo
authors.forename: Lloyd V
authors.initials: LV
authors.lastname: Flores
authors.forename: David W
authors.initials: DW
authors.lastname: Christianson
mesh_terms: D001120:Arginine / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D019791:Guanidine / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006860:Hydrogen Bonding; D019216:Metals, Heavy / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
chemical_list: D019216:Metals, Heavy; D011506:Proteins; D001120:Arginine; D019791:Guanidine