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STUDIES ON S‐ADENOSYLHOMOCYSTEINE INHIBITION OF HISTAMINE TRANSMETHYLATION IN BRAIN
Author(s) -
Baudry M.,
Chast F.,
Schwartz J.C.
Publication year - 1973
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.1471-4159.1973.tb12099.x
Subject(s) - histamine , histamine n methyltransferase , transmethylation , methylation , chemistry , methyltransferase , enzyme , non competitive inhibition , pyrogallol , biochemistry , pharmacology , biology , receptor , histamine h2 receptor , gene , antagonist
— The mechanism of histamine methyltransferase (HMT) inhibition by S ‐adenosylhomocysteine (SAH) has been investigated on a partially purified enzyme from guinea‐pig brain. The kinetic data indicated that this inhibition was competitive with respect to S ‐adenosylmethionine (SAMe) and noncompetitive with respect to histamine. The K t , values (about 5 ± 10 −6 M in both cases) indicated that SAH had a higher affinity than SAHe or histamine for the enzyme. In rats, after administration of a small dose of SAH, methylation of intracisternally injected [ 3 H]histamine was not modified. However, treatment with l ‐DOPA or pyrogallol induced a decrease in [ 3 H]histamine methylation, presumably due to a modification in the SAMe/SAH ratio in the brain. Hence, histamine methylation in brain could be regulated according to the value of this ratio and thus related to methylation of other biogenic amines.