title: Lessened malate inhibition of guard-cell phosphoenolpyruvate carboxylase velocity during stomatal opening.
abstract: Leaflets of Vicia faba with closed stomata or with opening stomata were freeze-dried. Excised guard-cell pairs were assayed individually under suboptimal conditions (pH 7.1 and subsaturating substrate) for phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) using quantitative histochemical procedures. L-Malate, 400 microM, significantly inhibited guard-cell PEPC activity of closed stomata but not that of opening stomata. We postulate that the lessened sensitivity of guard-cell PEPC activity to malate inhibition is an important regulatory feature of stomatal opening, which is associated with malate accumulation.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee 32306-3050.
authors.forename: S Q
authors.initials: SQ
authors.lastname: Zhang
authors.forename: W H
authors.initials: WH
authors.lastname: Outlaw
authors.forename: R
authors.initials: R
authors.lastname: Chollet
mesh_terms: D007887:Fabaceae / Q000166:cytology / Q000201:enzymology* / Q000502:physiology; D008293:Malates / Q000494:pharmacology; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism*; D017440:Photoperiod; D010946:Plants, Medicinal
chemical_list: D008293:Malates; C030298:malic acid; D010730:Phosphoenolpyruvate Carboxylase