Open AccessPutrescine‐Sensitive (Artifactual) and Insensitive (Biosynthetic) S ‐Adenosyl‐L‐Methionine Decarboxylase Activities of Lathyrus sativus Seedlings
Author(s) -
SURESH M. Rangarajan,
ADIGA P. Radhakantha
Publication year - 1977
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1977.tb11835.x
Subject(s) - putrescine , diamine oxidase , arginine decarboxylase , biochemistry , chemistry , adenosylmethionine decarboxylase , polyamine oxidase , methylglyoxal , spermidine , ornithine decarboxylase , polyamine , amine oxidase , methionine , enzyme , amino acid
The crude extracts of 3‐day‐old etiolated seedlings of Lathyrus sativus contained two S ‐adenosyl‐L‐methionine decarboxylase activities. The artifactual putrescine‐dependent activity was due to the H 2 O 2 generated by diamine oxidase (EC 1.4.3.6) of this plant system and was inhibited by catalase. This observation was confirmed by using an electrophoretically and immunologically homogeneous preparation of L. sativus diamine oxidase. In the presence of putrescine, diamine oxidase, in addition to S ‐adenosylmethionine, decarboxylated L‐lysine, L‐arginine, L‐ornithine, L‐methionine and L‐glutamic acid to varying degrees. The decarboxylation was not metal‐ion dependent. The biosynthetic S ‐adenosylmethionine decarboxylase (EC 4.1.1.21) was detected after removing diamine oxidase specifically from the crude extracts by employing an immunoaffinity column. This Mg 2+ ‐dependent decarboxylase was not stimulated by putrescine or inhibited by catalase. The enzyme activity was inhibited by semicarbazide, 4‐bromo‐3‐hydroxybenzoylamine dihydrogen phosphate and methylglyoxal‐bis (guanylhydrazone). It was largely localized in the shoots of the etiolated seedlings and was purified 40‐fold by employing a p ‐hydroxymercuribenzoate/AH‐Sepharose affinity column, which also separated the decarboxylase activity from spermidine synthase.