1BI6: NMR STRUCTURE OF BROMELAIN INHIBITOR VI FROM PINEAPPLE STEM

Citation:
Abstract
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.
PDB ID: 1BI6Download
MMDB ID: 4321
PDB Deposition Date: 1995/12/7
Updated in MMDB: 2017/12
Experimental Method:
solution nmr
Source Organism:
Similar Structures:
Biological Unit for 1BI6: dimeric; determined by author
Molecular Components in 1BI6
Label Count Molecule
Proteins (2 molecules)
1
Bromelain Inhibitor VI
Molecule annotation
1
Bromelain Inhibitor VI
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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