β Scribed by Rast, Dora ;Bachofen, Reinhard
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Carboxylation Reactions in Agaricus bisporus II. Acetone as a C02-Acceptor Summary. 1. Acetone is shown to stimulate the incorporation of bicarbonate into organic acids by cell-free extracts of Agaricus bisporus. Radioactive malate, fumarate and aspartate were determined as end products of this C02-fixation , regardless whether HlaC03 -or 1,3-1aC-acetone was used as a tracer. Acetoacetate is an intermediate in the reaction sequence leading from acetone to these acids, an observation that indicates a carboxylation of the ketone.
The incorporation of ItCO~-mentioned above requires the presence of ATP, Mg 2+, CoA and GSH; it is inhibited by avidin and pCMB. It is therefore suggested that the carboxylation of acetone depends on biotin, at least in an indirect manner.
The presence of acetoacetate deearboxylase in the common mushroom is shown and possible reasons for ketosis as occuring in the first phase of fruiting are discussed.
/assung. 1. Aceton stimuliert die Inkorporation yon HltC08-in organische Sguren durch zellfreie Extrakte yon Agaricus bisporus. Als Endprodukte dieser C02-Fixierung treten radioaktives Malat, Fumarat sowie Aspartat auf, und zwar unabh~ngig davon, ob H14CQoder 1,3-14C-Aeeton als Tracer verwendet wird. Beim eigentlichen Carboxylierungsprodukt handelt es sieh sehr wahrseheinlich um Acetessigsi~ure. 2. Da die Inkorporation yon 14C02 im Acetonsystem die Gegenwart yon ATP, Mg ~+, CoA sowie GSH erfordert und durch Avidln und pCMB eine starke Hemmung erfi~hrt, mug die Carboxylierung yon Aceton zum mindesten indirekt yon einem Biotinenzym abh~ngig sein.
π SIMILAR VOLUMES
Cell-free extracts from Agaricus bisporus catalyze the synthesis of malate, fumarate and aspartate from pyruvate and CO~ in the presence of Mn ~+, and from phosphoenolpyruvate and CO~ with Mg ~+ (partially replaceable by Max+). The carboxylatioa of pyruvate is highly stimulated by ATP and NADPtt s,