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Protein‐O‐methyltransferase in brain synaptosomal fraction under normal, ischemic and hypoxic conditions. Possible role in neuronal function
Author(s) -
Pastuszko Anna,
Rafalowska Ursula
Publication year - 1984
Publication title -
acta neurologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.967
H-Index - 95
eISSN - 1600-0404
pISSN - 0001-6314
DOI - 10.1111/j.1600-0404.1984.tb07813.x
Subject(s) - endogeny , chemistry , dopamine , methyltransferase , ischemia , enzyme , biochemistry , endocrinology , medicine , gelatin , biology , methylation , gene
— Activity of protein‐O‐methyltransferase in synaptosomal fractions was obtained. K m values calculated for S‐adenosylmethionine as substrate were 1 μM and V max = 4.3 pmoles/mg p/min. In the presence of gelatin (exogenous protein acceptor), activity was about 3 times higher. Without gelatin, activity of endogenous protein‐O‐methyltransferase decreased by about 20% under hypoxic conditions and by about 15% in ischemia. Exogenous activity under both hypoxic and ischemic conditions did not change. These results can possibly be explained by the changes in methyl acceptor proteins. In normal conditions, after inhibition methylcarboxylation by S‐adenosyl‐L‐homocysteine, the decrease of GABA uptake and increase in the uptake of dopamine were observed. Uptake of serotonine and noradrenaline were unchanged.