Document Detail

Activation of phosphoinositide-specific phospholipase C delta from rat liver by polyamines and basic proteins.
MedLine Citation:
PMID:  1654825     Owner:  NLM     Status:  MEDLINE    
Phospholipase C from rat liver with a molecular weight of 87,000 (PLC delta) is stimulated by polyamines, basic proteins, and basic polyamino acids. The activation occurs in both the presence and the absence of detergents. Half-maximum activation by spermine is observed at 0.15 mM, with optimum effects between 0.2 and 0.5 mM. Spermine inhibits above 0.5 mM. Half-maximum activation by spermidine and putrescine is observed at 0.9 and 6 mM, respectively, with optimum effects at 2 and 5 mM, respectively. These polyamines also inhibit at higher concentrations. Neomycin activates the enzyme with an optimum concentration of 10 microM, but maximum activation is less than with polyamines. Half-maximum activation by histone 2B occurs at 0.5 micrograms/ml (36 nM), with maximum stimulation at 1.5 micrograms/ml. Other histones, protamine, melittin, poly-L-ornithine, poly-L-lysine, poly-D-lysine, and poly-L-arginine, activate optimally at 3-10 micrograms/ml. Myelin basic protein and lysozyme activate optimally at 50-100 micrograms/ml. Typical activations are three- to eightfold, but under some conditions the enzyme shows little or no activity in the absence of basic activators. The basic activators lower the salt concentration required for maximal activity. In the case of the detergent-micelle assay, histone shifts the optimum NaCl concentration from 350 to 200 mM for PIP2, from 260 to 100 mM for PIP, and from 150 to 0 mM for PI. Histone potentiates the activation by Ca2+, but does not shift the optimum Ca2+ concentration. The optimum salt and Ca2+ concentrations are linked, such that a decrease in the concentration of one decreases the optimum concentration of the other. Activation by histone is diminished by MgCl2 in a concentration-dependent manner.
M T Haber; T Fukui; M S Lebowitz; J M Lowenstein
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Archives of biochemistry and biophysics     Volume:  288     ISSN:  0003-9861     ISO Abbreviation:  Arch. Biochem. Biophys.     Publication Date:  1991 Jul 
Date Detail:
Created Date:  1991-10-24     Completed Date:  1991-10-24     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0372430     Medline TA:  Arch Biochem Biophys     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  243-9     Citation Subset:  IM    
Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254.
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MeSH Terms
Enzyme Activation / drug effects
Liver / enzymology*
Phosphatidylinositols / metabolism
Polyamines / pharmacology
Proteins / pharmacology
Salts / pharmacology
Type C Phospholipases / metabolism*
Reg. No./Substance:
0/Phosphatidylinositols; 0/Polyamines; 0/Proteins; 0/Salts; EC 3.1.4.-/Type C Phospholipases

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