Document Detail


Selenium-dependent glutathione peroxidases from ovine and bovine erythrocytes occur as longer chain forms than previously recognized.
MedLine Citation:
PMID:  1567207     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
From the cDNA sequence of bovine glutathione peroxidase [G. T. Mullenbach, A. Tabrizi, B. D. Irvine, G. I. Bell, J. A. Tainer, and R. A. Hallewell (1988) Protein Eng. 2, 239-246], it is known that the full transcript represents a 205-residue protein with the N-terminal sequence of MCAAQRSAAALAAAAPRTV. However, a protein primary structure determination on what is believed to be the mature protein showed an N-terminal sequence of AAALAAAAPRTV [W. A. Günzler, G. J. Steffens, A. Grossmann, S. A. Kim, F. Otting, A. Wendel, and L. Flohe (1984) Hoppe-Seyler's Z. Physiol. Chem. 365, 195-212], suggesting processing of the N-terminal 7 residues to give the mature protein. It is shown here that the normal form of bovine erythrocyte glutathione peroxidase is most likely the full transcript lacking the N-terminal methionine, and that subsequent proteolysis during isolation results in formation first of the form characterized by Günzler et al. and then of two slightly smaller species, the smaller of which appears to be similar to that examined crystallographically [O. Epp, R. Ladenstein, and A. Wendel (1983) Eur. J. Biochem. 133, 51-69]. For ovine erythrocyte glutathione peroxidase the same behavior is seen, with initial isolation of a high-molecular-weight form that is subsequently proteolyzed to two intermediate forms and a final form that migrates at the same position on acrylamide gels as the lowest-molecular-weight form of the bovine enzyme. The contaminating protease can be inhibited by the addition of 10 mM EDTA, suggesting that it is a metalloprotease. Activity measurements on the intact and processed forms of the ovine enzyme show no significant differences with both hydrogen peroxide and t-butyl hydroperoxide as substrates. These results suggest that both bovine and ovine erythrocyte glutathione peroxidases consist of a globular core that is relatively resistant to proteolysis and an N-terminal tail of approximately 17 residues that seems to be exposed and is very sensitive to proteolysis. This tail, which contains many hydrophobic residues, is predicted to be largely alpha-helical and may be involved in anchoring the enzyme at or close to the membrane surface.
Authors:
P Gettins; D Dyal; B Crews
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Archives of biochemistry and biophysics     Volume:  294     ISSN:  0003-9861     ISO Abbreviation:  Arch. Biochem. Biophys.     Publication Date:  1992 May 
Date Detail:
Created Date:  1992-05-15     Completed Date:  1992-05-15     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0372430     Medline TA:  Arch Biochem Biophys     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  511-8     Citation Subset:  IM    
Affiliation:
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
Animals
Cattle
Electrophoresis, Polyacrylamide Gel
Erythrocytes / enzymology*
Glutathione Peroxidase / blood*,  genetics,  isolation & purification
Kinetics
Molecular Sequence Data
Molecular Weight
Pancreatic Elastase / metabolism
Selenium / pharmacology*
Sheep
Trypsin / metabolism
Grant Support
ID/Acronym/Agency:
GM-39509/GM/NIGMS NIH HHS; HD-20583/HD/NICHD NIH HHS; HD-20922/HD/NICHD NIH HHS
Chemical
Reg. No./Substance:
7782-49-2/Selenium; EC 1.11.1.9/Glutathione Peroxidase; EC 3.4.21.36/Pancreatic Elastase; EC 3.4.21.4/Trypsin

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