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Studies on the hydrophobic region of PEP carboxylase from sorghum leavesin solution by fluorimetric titration

Tang Xiaoyi, Zha Jingjuan, Shi Jiaonai

Shanghai Institute of Plant Physiology, Academia Sinica,Shanghai；China(200032)

Abstract

When PEPC was titrated with the hydrophobic probe-ANS in the presence ofvarying concentration of an allosteric effector, the emission fluorescenceintensity(I) increased in a hyperbolic manner, then double reciprocal plots ofI vs ANS concentration was used to estimate the I_(max)in the presence ofvarying concentration of allosteric effector. The influence of allostericeffectors on fluorescence emission from the enzyme-ANS complex is shown inTable 1. Gly and G6P are two positive effectors which sctivate of PEPC fromC_(4)plants. Fig.2 shows the fluorimetric titration of PEPC with ANS carriedout in the presence of varying concentration of Gly. The I_(max) decreasedwith an increase of Gly concentration. When PEPC was titrated with ANS in thepresence of varying concentration of G6P, the I_(max) did not showsignificant change. In contrast, when PEPC was preincubated with 3.6 mmol/L ofGly and then titrated with ANS, the I_(max)a decreased with increasingconcentration of G6P. When PEPC was titrated with ANS in the presence ofvarying concentration of malate, the I_(max) markedly decreased in ahyperbolic manner When PEPC was titrated with ANS in the presence of ....

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Citing This Article：

Tang Xiaoyi, Zha Jingjuan, Shi Jiaonai. Studies on the hydrophobic region of PEP carboxylase from sorghum leavesin solution by fluorimetric titration. Acta Physiol Sin 1994; 46 (2): (in Chinese with English abstract).