1cb3
From Proteopedia
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LOCAL INTERACTIONS DRIVE THE FORMATION OF NON-NATIVE STRUCTURE IN THE DENATURED STATE OF HUMAN ALPHA-LACTALBUMIN: A HIGH RESOLUTION STRUCTURAL CHARACTERIZATION OF A PEPTIDE MODEL IN AQUEOUS SOLUTION
Overview
There are a small number of peptides derived from proteins that have a, propensity to adopt structure in aqueous solution which is similar to the, structure they possess in the parent protein. There are far fewer examples, of protein fragments which adopt stable nonnative structures in isolation., Understanding how nonnative interactions are involved in protein folding, is crucial to our understanding of the topic. Here we show that a small, 11 amino acid peptide corresponding to residues 101-111 of the protein, alpha-lactalbumin is remarkably structured in isolation in aqueous, solution. The peptide has been characterized by 1H NMR, and 170, ROE-derived constraints were used to calculate a structure. The, calculations yielded a single, high-resolution structure for residues, 101-107 that is nonnative in both the backbone and side-chain, conformations. In the pH 6.5 crystal structure, residues 101-105 are in an, irregular turn-like conformation and residues 106-111 form an alpha-helix., In the pH 4.2 crystal structure, residues 101-105 form an alpha-helix, and, residues 106-111 form a loopike structure. Both of these structures are, significantly different from the conformation adopted by our peptide. The, structure in the peptide model is primarily the result of local side-chain, interactions that force the backbone to adopt a nonnative 310/turn-like, structure in residues 103-106. The structure in aqueous solution was, compared to the structure in 30% trifluoroethanol (TFE), and clear, differences were observed. In particular, one of the side-chain, interactions, a hydrophobic cluster involving residues 101-105, is, different in the two solvents and residues 107-111 are considerably more, ordered in 30% TFE. The implications of the nonnative structure for the, folding of alpha-lactalbumin is discussed.
About this Structure
1CB3 is a Single protein structure of sequence from [1] with ACE and NH2 as ligands. Full crystallographic information is available from OCA.
Reference
Local interactions drive the formation of nonnative structure in the denatured state of human alpha-lactalbumin: a high resolution structural characterization of a peptide model in aqueous solution., Demarest SJ, Hua Y, Raleigh DP, Biochemistry. 1999 Jun 1;38(22):7380-7. PMID:10353850
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