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STUDIES ON THE NATURAL SUBSTRATE FOR PROTEIN METHYLASE II IN MAMMALIAN BRAIN AND BLOOD
Author(s) -
Kim S.,
Wasserman L.,
Lew Betty,
Paik W. K.
Publication year - 1975
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.1471-4159.1975.tb03838.x
Subject(s) - substrate (aquarium) , substrate specificity , natural (archaeology) , neuroscience , biology , biochemistry , chemistry , enzyme , ecology , paleontology
—The activity of protein methylase II ( S ‐adenosylmethionine:protein‐carboxyl methyltransferase, EC 2.1.1.24), which methylates (esterifies) free carboxyl groups in the substrate protein, was measured in several mammalian organs in an effort to elucidate the nature of the natural substrate for the enzyme. The highest endogenous substrate activity was found in posterior and anterior pituitary glands, possibly in association with neurosecretory granules. In other parts of the brain endogenous substrates are lacking, although the cytosol fractions contain high activity of the enzyme which methylates exogenously added substrates. Rat whole blood also contains endogenous substrate protein. The protein precipitated by 50% (NH 4 ) 2 SO 4 contained active substrate protein whereas blood protein methylase II is localized exclusively in the erythrocytes. Cohn fractions I, II and III are more active as substrate for protein methylase II than fraction V.