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Inhibitory plant serpins with a sequence of three glutamine residues in the reactive center.
- Source :
-
Biological chemistry [Biol Chem] 2005 Dec; Vol. 386 (12), pp. 1319-23. - Publication Year :
- 2005
-
Abstract
- Serpins appear to be ubiquitous in eukaryotes, except fungi, and are also present in some bacteria, archaea and viruses. Inhibitory serpins with a glutamine as the reactive-center P1 residue have been identified exclusively in a few plant species. Unique serpins with a reactive center sequence of three Gln residues at P3-P1 or P2-P1' were isolated from barley and wheat grain, respectively. Barley BSZ3 was an irreversible inhibitor of chymotrypsin, with a second-order association rate constant for complex formation k(a)' of the order of 10(4) M(-1) s(-1); however, only a minor fraction of the serpin molecules reacted with chymotrypsin, with the majority insensitive to cleavage in the reactive center loop. Wheat WSZ3 was cleaved specifically at P8 Thr and was not an inhibitor of chymotrypsin. These reactive-center loops may have evolved conformations that are optimal as inhibitory baits for proeinases that specifically degrade storage prolamins containing Gln-rich repetitive sequences, most likely for digestive proteinases of insect pests or fungal pathogens that infect cereals. An assembled full-length amino acid sequence of a serpin expressed in cotton boll fiber (GaZ1) included conserved regions essential for serpin-proteinase interaction, suggesting inhibitory capacity at a putative reactive center P2-P2' with a sequence of four Gln residues.
- Subjects :
- Amino Acid Sequence
Chymotrypsin antagonists & inhibitors
Chymotrypsin metabolism
Kinetics
Molecular Sequence Data
Serine Proteinase Inhibitors isolation & purification
Serine Proteinase Inhibitors metabolism
Serpins chemistry
Serpins isolation & purification
Glutamine chemistry
Gossypium chemistry
Hordeum chemistry
Serine Proteinase Inhibitors chemistry
Serpins metabolism
Triticum chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1431-6730
- Volume :
- 386
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- Biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 16336127
- Full Text :
- https://doi.org/10.1515/BC.2005.150