Articles
REGULATION OF MALIC ACID METABOLISM IN BERRIES OF VITIS VINIFERA
Article number
139_16
Pages
117 – 122
Language
Abstract
Based on tracer experiments with sucrose-U-14C, administered to grape berries before and after the onset of ripening, it is concluded that the decrease in malic acid during maturation is the result of reduced malate synthesis in combination with an accelerated catabolic rate.
As might be expected from the available physiological data, which generally favour a decarboxylative action of malic enzyme (ME; EC 1.1.1.40) in fruit ripening, no negative correlation between areas of high enzymic activity and malate concentration was detectable in green berries, while in the maturing fruit the zone of highest ME activity also had the lowest malic acid levels.
As might be expected from the available physiological data, which generally favour a decarboxylative action of malic enzyme (ME; EC 1.1.1.40) in fruit ripening, no negative correlation between areas of high enzymic activity and malate concentration was detectable in green berries, while in the maturing fruit the zone of highest ME activity also had the lowest malic acid levels.
The physiological potential of certain in vitro properties of grape ME, such as the interrelationship between pH and enzymic affinity for malate, as well as the inhibitory effect of high NADPH proportions on malic acid decarboxylation, are discussed.
Publication
Authors
D. Possner, H.P. Ruffner, D.M. Rast
Keywords
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