Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.1 (chymotrypsin)
 10,938 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Limited proteolysis of glutathione transferase P1-1 (GSTP1-1) by chymotrypsin generates a 34-kDa GSTP1-1 fragment (a dimer of the 17-kDa subunit composed by residues 48-207) containing the whole C-terminal domain and a part (about 15%) of the N-terminal domain (residues 48-76, i.e., the structural elements beta 3, beta 4, and alpha C). The structural and functional properties of this large fragment have been investigated by analyzing its binding properties to 2-p-toluidinylnaphthalene-6-sulfonate (TNS) extrinsic probe, the TNS displacement technique, and the molecular modeling approach. The results obtained indicated that the 34-kDa GSTP1-1 fragment maintains an hydrophobic pocket with the same structural properties of the corresponding GSTP1-1 hydrophobic binding site. In addition, the 34-kDa GSTP1-1 binds a number of hydrophobic compounds such as 1-chloro-2,4-dinitrobenzene, hemin, and bilirubin with the same affinity of the native enzyme. Being structurally and functionally autonomous, this fragment, mostly constituted by domain II, appears as an independent folding unit in the protein. Nevertheless, in the entire native protein, interdomain interactions occur and are responsible for the major solvent exposure of the H-site in the presence of glutathione.
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PMID:Structural and functional properties of the 34-kDa fragment produced by the N-terminal chymotryptic cleavage of glutathione transferase P1-1. 786 46

Limited proteolysis of glutathione transferase P1-1 (GSTP1-1) by chymotrypsin performed at 20 degrees and 30 degrees C mainly generates two complementary peptides of 17 kDa and 6 kDa molecular mass with concomitant loss of catalytic capacity. Sequence analysis of these peptides showed that the peptide bond between Tyr47 and Gly48 was cleaved. The analysis of the recently resolved three-dimensional structure of GSTP1-1 [Reinemer, P., Dirr, H. W., Ladenstein, R., Huber, R., Lo Bello, M., Federici, G. & Parker, M. W. (1992) J. Mol. Biol. 227, 214-226] suggests that the proteolytically cleaved bond results located in a portion of the polypeptide chain lining the G-site which has been demonstrated to be part of an exposed and flexible region of the N-terminal domain (structural elements alpha B1 and alpha B2) [Aceto, A., Caccuri, A. M., Sacchetta, P., Bucciarelli, T., Dragani, B., Rosato, N., Federici, G. & Di Ilio, C. (1992) Biochem. J. 285, 241-245]. The fragments which are generated by proteolysis at 20 degrees C, remain linked by noncovalent interaction in a complex (nicked GSTP1-1) which is dissociated by incubation at higher temperatures. As shown by circular dichroic analysis, although inactive, nicked GSTP1-1 retains an overall secondary structure closely resembling that of the parent enzyme. However, the fluorescence data of the nicked GSTP1-1 indicate that the Trp38, which is near the chymotrypsin-cleavable bond, becomes exposed in a more polar environment. This indicates that, in the nicked enzyme, the polypeptide portion containing the structural elements alpha B1 and alpha B2 has more freedom of fluctuation. The fact that this polypeptide chain portion contains two essential amino acid residues of the G-site (Trp38 and Lys42) might account for the loss of ability to bind glutathione by the nicked enzyme which is consequently catalytically inactive. Proteolysis performed at 30 degrees C generated a homodimeric 17-kDa fragment. The structural analysis of this fragment suggests that the GSTP1-1 alpha C helix, which is located in the domain I and is thought to be involved in the inter-domain interaction, could exert a critical role in maintaining the native folding of domain II.
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PMID:Investigation of intra-domain and inter-domain interactions of glutathione transferase P1-1 by limited chymotryptic cleavage. 828 36