ISSN:
1432-2048
Keywords:
Guard cell protoplast
;
Malate sensitivity
;
Phosphoenolpyruvate carboxylase
;
Protoplast (guard cell)
;
Vicia (guard cells)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Properties of phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) obtained from isolated guard-cell protoplasts of Vicia faba L. were determined following rapidly desalting of the extract on a Sephadex G 25 column. The activity of PEP carboxylase was measured as a function of PEP and malate concentration, pH and K+ concentration within 2–3 min after homogenization of the guard-cell protoplasts. The activity of this enzyme was stimulated by PEP concentrations of 0.1 to 0.75 mM and by K+ ions (12 mM), but inhibited by PEP concentrations above 1 mM and by malate. Changes in the Km(PEP) and Vmax values with increasing malate concentrations (2.5 and 5 mM) indicate that the malate level, varying in relation to the physiological state of guard cells, plays an important role in regulating the properties of phosphoenolpyruvate carboxylase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00397443
