Selectivity in heavy metal- binding to peptides and proteins.
The metal-binding affinities and three-dimensional structures of three synthetic 18-residue peptides with sequences derived from that of the highly conserved metal-binding motif MXCXXC found in many heavy metal-binding proteins were determined. A change in register of the cysteines and alanines of the sequence from the periplasmic mercury-binding protein, MerP, i.e., CAAC, CACA, and CCAA, affects the specificity of metal binding, in particular, the peptide with vicinal cysteines binds only mercury. The three-dimensional structures of the mercury-bound forms of the three peptides determined in solution by NMR spectroscopy peptides differ considerably, even though they are all linear bicoordinate complexes. The three-dimensional structure of the peptide with CAAC bound to Cd(II) demonstrates that the metal-binding loop is malleable enough to accommodate modes of coordination other than linear bicoordinate.
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
Tara M
TM
DeSilva
Gianluigi
G
Veglia
Fernando
F
Porcelli
Andrew M
AM
Prantner
Stanley J
SJ
Opella
D000595:Amino Acid Sequence; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D002942:Circular Dichroism; D019216:Metals, Heavy / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*
D001704:Biopolymers; D019216:Metals, Heavy; D010455:Peptides; D011506:Proteins