Document Detail


Solubilization and partial characterization of a phosphoprotein phosphatase from human myelin.
MedLine Citation:
PMID:  23846     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The phosphoprotein phosphatase (phosphoprotein phosphohydrolase, EC 3.1.3.16) solubilized from human central nervous system myelin has been shown to possess a comparatively high degree of specificity towards myelin basic protein, a constituent of the membrane and most likely its natural substrate, rather than the mixed histones. The enzyme has a pH optimum of 7.5. Hydrolysis of both the substrates is stimulated by dithiothreitol and is almost completely dependent upon the presence of divalent metal ions. The maximum rate of dephosphorylation of basic protein is attained in the presence of 125 micrometer Mn2+ whereas a much higher concentration of Mg2+ (50--100 mM) is required for the optimal dephosphorylation of histones. The dephosphorylation of basic protein was also stimulated by Triton X-100 (0.15%, v/v) and was shown to result from a 3-fold increase in the V of the reaction catalyzed by the phosphatase. The apparent Km values for basic protein and histones were unaffected by the presence of Triton X-100 and were found to be approx. 1 and approx. 160 micrometer, respectively. Under optimal conditions of assay, the phosphatase cleaved approx. 32 and approx. 0.7 nmol of orthophosphate.min-1.mg-1 of protein from basic protein and histones, respectively.
Authors:
J E Yourist; F Ahmad; A H Brady
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  522     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1978 Feb 
Date Detail:
Created Date:  1978-04-17     Completed Date:  1978-04-17     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  452-64     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Corpus Callosum / enzymology
Dithiothreitol / pharmacology
Histones / metabolism
Humans
Hydrogen-Ion Concentration
Kinetics
Magnesium / pharmacology
Manganese / pharmacology
Myelin Proteins / metabolism
Myelin Sheath / enzymology*
Phosphoprotein Phosphatases / isolation & purification,  metabolism*
Polyethylene Glycols / pharmacology
Chemical
Reg. No./Substance:
0/Histones; 0/Myelin Proteins; 0/Polyethylene Glycols; 3483-12-3/Dithiothreitol; 7439-95-4/Magnesium; 7439-96-5/Manganese; EC 3.1.3.16/Phosphoprotein Phosphatases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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