1O8Z

Solution structure of SFTI-1(6,5), an acyclic permutant of the proteinase inhibitor SFTI-1, cis-trans-trans conformer (ct-A)

1O8Z の概要

• エントリーDOI: 10.2210/pdb1o8z/pdb
• 関連するPDBエントリー: 1JBL 1JBN 1O8Y 1SFI
• 分子名称: CYCLIC TRYPSIN INHIBITOR (1 entity in total)
• 機能のキーワード: protease inhibitor, bowman-birk inhibitor, sfti-1, acyclic permutant
• 由来する生物種: HELIANTHUS ANNUUS L. (SUNFLOWER)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 1535.83

構造登録者

Marx, U.C.,Craik, D.J. (登録日: 2002-12-09, 公開日: 2003-03-13, 最終更新日: 2024-11-20)

主引用文献

Marx, U.C.,Korsinczky, M.,Schirra, H.,Jones, A.,Condie, B.,Otvos, L.,Craik, D.J.
Enzymatic Cyclization of a Potent Bowman-Birk Protease Inhibitor, Sunflower Trypsin Inhibitor-1, and Solution Structure of an Acyclic Precursor Peptide
J.Biol.Chem., 278:21782-, 2003

PubMed Abstract: The most potent known naturally occurring Bowman-Birk inhibitor, sunflower trypsin inhibitor-1 (SFTI-1), is a bicyclic 14-amino acid peptide from sunflower seeds comprising one disulfide bond and a cyclic backbone. At present, little is known about the cyclization mechanism of SFTI-1. We show here that an acyclic permutant of SFTI-1 open at its scissile bond, SFTI-1[6,5], also functions as an inhibitor of trypsin and that it can be enzymatically backbone-cyclized by incubation with bovine beta-trypsin. The resulting ratio of cyclic SFTI-1 to SFTI-1[6,5] is approximately 9:1 regardless of whether trypsin is incubated with SFTI-1[6,5] or SFTI-1. Enzymatic resynthesis of the scissile bond to form cyclic SFTI-1 is a novel mechanism of cyclization of SFTI-1[6,5]. Such a reaction could potentially occur on a trypsin affinity column as used in the original isolation procedure of SFTI-1. We therefore extracted SFTI-1 from sunflower seeds without a trypsin purification step and confirmed that the backbone of SFTI-1 is indeed naturally cyclic. Structural studies on SFTI-1[6,5] revealed high heterogeneity, and multiple species of SFTI-1[6,5] were identified. The main species closely resembles the structure of cyclic SFTI-1 with the broken binding loop able to rotate between a cis/trans geometry of the I7-P8 bond with the cis conformer being similar to the canonical binding loop conformation. The non-reactive loop adopts a beta-hairpin structure as in cyclic wild-type SFTI-1. Another species exhibits an iso-aspartate residue at position 14 and provides implications for possible in vivo cyclization mechanisms.

PubMed: 12621047
DOI: 10.1074/JBC.M212996200

実験手法

SOLUTION NMR