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The Effects of Various Incubation Temperatures, Particulate Isolation, and Possible Role of Calmodulin on the Activity of the Base Exchange Enzymes of Rat Brain
Author(s) -
Buchanan Alfred G.,
Kanfer J. N.
Publication year - 1980
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1980.tb07077.x
Subject(s) - calmodulin , ethanolamine , chemistry , enzyme , homogenization (climate) , biochemistry , serine , microsome , choline , biology , biodiversity , ecology
The involvement of calmodulin in the choline, ethanolamine, and serine exchange activities of rat brain microsomes was investigated. Calmodulin stimulated choline exchange activity to a greater extent than ethanolamine and serine exchange activities. The three base exchange activities were inhibited by antipsychotic drugs believed to prevent calmodulin interaction, but not by calmodulin‐binding protein. The solutions employed for tissue homogenization and subsequent isolation of microsomes greatly influenced the base exchange activites. The process of resuspending isolated microsomes and recentrifugation, or “washing,” produced major losses of detectable activity. The base exchange enzyme activities were maximal at 45°, and Arrhenius plots revealed a common transition temperature of 31°. The activation energies for the base exchange reactions decreased at temperatures above the observed transition temperature. Kinetic data, K m and V max , for the base exchange activities at 27, 37, and 45° are presented. Buchanan A. G. and Kanfer J. N. The effects of various incubation temperatures, particulate isolation, and possible role of calmodulin on the activity of the base exchange enzymes of rat brain. J. Neurochem. 35, 814–822 (1980).