1bi6
From Proteopedia
NMR STRUCTURE OF BROMELAIN INHIBITOR VI FROM PINEAPPLE STEM
Overview
Bromelain inhibitor VI from pineapple stem (BI-VI) is a unique double-chain inhibitor with an 11-residue light chain and a 41-residue heavy chain by disulfide bonds and inhibits the cysteine proteinase bromelain competitively. The structure of BI-VI in aqueous solution was determined using nuclear magnetic resonance spectroscopy and simulated annealing-based calculations. Its three-dimensional structure was shown to be composed of two distinct domains, each of which is formed by a three-stranded antiparallel beta-sheet. Unexpectedly, BI-VI was found to share a similar folding and disulfide bond connectivities not with cystatin superfamily inhibitors which inhibit the same cysteine proteinases but with the Bowman-Birk trypsin/chymotrypsin inhibitor from soybean (BBI-I). BBI-I is a 71-residue inhibitor which has two independent inhibitory sites toward the serine proteinases trypsin and chymotrypsin. These structural similarities with BBI-I suggest that they have evolved from a common ancestor and differentiated in function during a course of molecular evolution.
About this Structure
1BI6 is a Protein complex structure of sequences from Ananas comosus. Full crystallographic information is available from OCA.
Reference
Solution structure of bromelain inhibitor IV from pineapple stem: structural similarity with Bowman-Birk trypsin/chymotrypsin inhibitor from soybean., Hatano K, Kojima M, Tanokura M, Takahashi K, Biochemistry. 1996 Apr 30;35(17):5379-84. PMID:8611527 Page seeded by OCA on Fri May 2 11:32:40 2008
