1t9e

From Proteopedia

NMR solution structure of a disulfide analogue of the cyclic sunflower trypsin inhibitor SFTI-1

Overview

SFTI-1 is a novel 14 amino acid peptide comprised of a circular backbone, constrained by three proline residues, a hydrogen-bond network, and a, single disulfide bond. It is the smallest and most potent known, Bowman-Birk trypsin inhibitor and the only one with a cyclic peptidic, backbone. The solution structure of [ABA(3,11)]SFTI-1, a, disulfide-deficient analogue of SFTI-1, has been determined by (1)H NMR, spectroscopy. The lowest energy structures of native SFTI-1 and, [ABA(3,11)]SFTI-1 are similar and superimpose with a root-mean-square, deviation over the backbone and heavy atoms of 0.26 +/- 0.09 and 1.10 +/-, 0.22 A, respectively. The disulfide bridge in SFTI-1 was found to be a, minor determinant for the overall structure, but its removal resulted in a, slightly weakened hydrogen-bonding network. To further investigate the, role of the disulfide bridge, NMR chemical shifts for the backbone, H(alpha) protons of two disulfide-deficient linear analogues of SFTI-1, [ABA(3,11)]SFTI-1[6,5] and [ABA(3,11)]SFTI-1[1,14] were measured. These, correspond to analogues of the cleavage product of SFTI-1 and a putative, biosynthetic precursor, respectively. In contrast with the cyclic peptide, it was found that the disulfide bridge is essential for maintaining the, structure of these open-chain analogues. Overall, the hydrogen-bond, network appears to be a crucial determinant of the structure of SFTI-1, analogues.

About this Structure

1T9E is a Single protein structure of sequence from [1]. Full crystallographic information is available from OCA.

Reference

Disulfide bond mutagenesis and the structure and function of the head-to-tail macrocyclic trypsin inhibitor SFTI-1., Korsinczky ML, Clark RJ, Craik DJ, Biochemistry. 2005 Feb 1;44(4):1145-53. PMID:15667208

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