| Absence of large-scale conformational change upon limited proteolysis of ovalbumin, the prototypic serpin. | |
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MedLine Citation:
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PMID: 2645277 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1H and 31P NMR spectroscopies have been used to examine the effects of limited proteolysis with subtilisin Carlsberg on the global conformation of ovalbumin and on the local environment of phosphoserine 344, a residue two positions removed from the site of proteolysis. Such limited proteolysis has been shown to result in excision of a hexapeptide from the region of the protein that, in other serine protease inhibitors (serpins), contains the reactive center. Based on the structure of the related serpin alpha 1-antitrypsin, it has been predicted that phosphoserine 344 should undergo a large change in environment upon proteolysis of ovalbumin (Löbermann, H., Tokuoka, R., Deisenhofer, J., and Huber, R. (1984) J. Mol. Biol. 177, 531-550). Proteolysis of ovalbumin produces a small upfield shift (0.15 ppm) of the 31P resonance of phosphoserine 344. In addition, the pKa of phosphoserine 344 is raised by 0.1 pH unit. At pH 8.5, phosphoserine 344 in cleaved ovalbumin (plakalbumin) is as accessible to hydrolysis by Escherichia coli alkaline phosphatase as it is in native ovalbumin. 1H NMR shows that dephosphorylation of serine 344 has an imperceptible effect on the protein's conformation. Similarly, little effect on conformation is seen by 1H NMR upon proteolysis of ovalbumin. These findings suggest that ovalbumin does not undergo a marked conformational change analogous to that inferred for the related members of the serpin superfamily, alpha 1-antitrypsin and antithrombin III, nor do the residues close to the site of proteolysis appear to change environment from that of an exposed loop to a buried strand of beta-sheet. These findings are not consistent with the hypothesis of Carrell and Owen ((1985) Nature 317, 730-732) for the role of the exposed loop in serpins of directly facilitating conformational change upon cleavage of the loop. Instead, it is proposed that cleavage of the exposed loop alters the solvent accessibility of residues formerly covered by the loop and that this provides the thermodynamic impetus for conformational change, perhaps by disruption of a salt bridge crucial to the integrity of the native structure. |
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Authors:
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P Gettins |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of biological chemistry Volume: 264 ISSN: 0021-9258 ISO Abbreviation: J. Biol. Chem. Publication Date: 1989 Mar |
Date Detail:
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Created Date: 1989-04-03 Completed Date: 1989-04-03 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 2985121R Medline TA: J Biol Chem Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 3781-5 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Chickens Hydrogen-Ion Concentration Magnetic Resonance Spectroscopy Ovalbumin / ultrastructure* Phosphoserine Protease Inhibitors* Protein Conformation Structure-Activity Relationship Subtilisins / pharmacology |
| Grant Support | |
ID/Acronym/Agency:
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HL32595/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Protease Inhibitors; 17885-08-4/Phosphoserine; 9006-59-1/Ovalbumin; EC 3.4.21.-/Subtilisins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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