Characterization of guanylyl cyclase in purified myelin

This study was undertaken to characterize the enzymatic properties of the particulate guanylyl cyclase previously shown to be present at a high level of activity in purified rat brain myelin. Significant activation was achieved by both Lubrol-PX and Triton X-100, the latter being somewhat more effec...

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Bibliographic Details
Published in:Neurochemical research 1996-04, Vol.21 (4), p.457-462
Main Authors: GRABOW, M, CHAKRABORTY, G, LEDEEN, R. W
Format: Article
Language:English
Subjects:
Animals
Biochemistry and metabolism
Biological and medical sciences
Brain Stem - enzymology
Central nervous system
Detergents
Enzyme Activation
Enzyme Stability
Fundamental and applied biological sciences. Psychology
Guanylate Cyclase - metabolism
Hydrogen-Ion Concentration
Kinetics
Male
Microsomes - enzymology
Myelin Sheath - enzymology
Octoxynol
Polidocanol
Polyethylene Glycols
Rats
Rats, Sprague-Dawley
Vertebrates: nervous system and sense organs
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Summary:This study was undertaken to characterize the enzymatic properties of the particulate guanylyl cyclase previously shown to be present at a high level of activity in purified rat brain myelin. Significant activation was achieved by both Lubrol-PX and Triton X-100, the latter being somewhat more effective. A pH optimum of 7.8 was observed, compared to 7.4 for microsomes. Employing 1.2 mM GTP with 1% Triton X-100, linearity of response was observed up to 60 min and approximately 1.2 mg of myelin protein. Kinetic analysis revealed Km values of 0.258mM and 0.486mM for myelin and microsomes, respectively, similar values being obtained by Lineweaver-Burke analysis or Direct Linear Plot. Vmax values were 20 and 266 pmol/mg protein/min for myelin and microsomes, respectively. Washing of the myelin with 0.5 M NaCl or 0.1% Na taurocholate did not remove a significant amount of guanylyl cyclase activity, indicating the enzyme to be intrinsic to the myelin sheath.
ISSN:0364-3190
1573-6903
DOI:10.1007/BF02527710