Metallothionein Peptide 31-61 - A Model for Metal-induced Protein Folding
Institution
Eastern Kentucky University
Faculty Advisor/ Mentor
C. Frank Shaw III
Abstract
The full realization of benefits from Genomics, the cataloguing and analysis of an organism’s genome, requires Proteomics, the study of protein structure and function, which is the next stage of the bioinformatics revolution. Proteins are produced in cells as linear polymers which must fold into their final, functional forms. One third of all proteins contain bound metal ions. Metallothionein is a protein that detoxifies Cd2+, Hg2+, oxidizing agents and alkylating antitumor agents, in addition to its role in Zn2+ and Cu+ metabolism. Metallothionein is structureless until it folds in the presence of metal ions. Hence, it is an excellent model for studying protein folding. The 20 cysteine residues among its 61 amino acids form two domains: the a-domain with 11 cysteines and 4 Cd2+ ions and the b-domain with 9 cysteines and 3 Cd2+ ions. Our hypothesis is that folding of the a-domain is initiated when two Cd 2+ ions bind to cysteines 33, 36, 37 at one end and cysteines 50, 57,59 and 60 at the other end. A mutated a-domain in which the four remaining cysteines (33, 41, 44 & 48) were replaced with alanine residues was prepared commercially by Genesys. Our research on the reactions of this peptide with cadmium during summer 2002 revealed that the peptide-cadmium complex is more labile than the complete protein.
Metallothionein Peptide 31-61 - A Model for Metal-induced Protein Folding
The full realization of benefits from Genomics, the cataloguing and analysis of an organism’s genome, requires Proteomics, the study of protein structure and function, which is the next stage of the bioinformatics revolution. Proteins are produced in cells as linear polymers which must fold into their final, functional forms. One third of all proteins contain bound metal ions. Metallothionein is a protein that detoxifies Cd2+, Hg2+, oxidizing agents and alkylating antitumor agents, in addition to its role in Zn2+ and Cu+ metabolism. Metallothionein is structureless until it folds in the presence of metal ions. Hence, it is an excellent model for studying protein folding. The 20 cysteine residues among its 61 amino acids form two domains: the a-domain with 11 cysteines and 4 Cd2+ ions and the b-domain with 9 cysteines and 3 Cd2+ ions. Our hypothesis is that folding of the a-domain is initiated when two Cd 2+ ions bind to cysteines 33, 36, 37 at one end and cysteines 50, 57,59 and 60 at the other end. A mutated a-domain in which the four remaining cysteines (33, 41, 44 & 48) were replaced with alanine residues was prepared commercially by Genesys. Our research on the reactions of this peptide with cadmium during summer 2002 revealed that the peptide-cadmium complex is more labile than the complete protein.