Regulation of C_4 Photosynthesis : Inactivation of Pyruvate, P_i Dikinase in Leaf and Chloroplast Extracts in Relation to Dark/Light Regulation in Vivo

概要

論文の詳細を見る
Active pyruvate, Pi dikinase in leaf or chloroplast extracts isolated from illuminated leaves was inactivated by incubating with ADP. With chloroplast extracts neither ATP nor AMP alone was effective. Half the maximum rate of inactivation was observed with about 55 μM ADP. The following evidence supported the view that ADP-mediated inactivation had a co-requirement for low concentrations of ATP [Buchanan (1980) Ann. Rev. Plant Physiol. 31: 341], adding hexokinase and glucose prevented inactivation by ADP [Feldhaus et al. (1975) Eur. J. Biochem. 57: 197], when GDP and UDP were added in place of ADP they mediated rapid inactivation only when ATP was also provided; GTP was not effective. ATP was apparently optimally effective at about 1μM or less. The rate of inactivation was approximately proportional to the square of extract concentration suggesting dependancy on a factor in the extracts in addition to active enzyme. The involvement of one or more heat labile protein factors was confirmed by trypsin treatment of extracts. Pyruvate,P_i dikinase inactivated by treatment with ADP was reactivated by incubating with P_i, a property common to the inactive enzyme extracted from darkened leaves. Thiol/disulphide interconversion was apparently not critical in the regulation of pyruvate,Pi dikinase.
日本植物生理学会の論文