The Ionic Strength Changes the Quaternary Structure of Phosphoenolpyruvate Carboxylase from Maize Leaves

Wagner, Richard; Gonzalez, D H; Podestá, Florencio E.; Andreo, Carlos S.

doi:10.1007/978-94-017-0516-5_113

Cited by 3 publications

(7 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is noteworthy that the substrates and the activator glucose (i-phosphate prevent the decay in activity that follows dissociation and that the salt effect is also affected by pH [64], A report by Angelopoulos et al 1731 on the stabilization of PEP carboxylase from C4 plants at high pH by non-ionic cosolvents also suggests that dissociation may occur when the enzyme is diluted at high pH. In this case, the decay in activity is protected by 6 substrate and activators [73].…”

Section: Physiological Regulationmentioning

confidence: 99%

Higher plant phosphoenolpyruvate carboxylase

1987

View full text Add to dashboard Cite

Section: Physiological Regulationmentioning

confidence: 99%

Higher plant phosphoenolpyruvate carboxylase

1987

View full text Add to dashboard Cite

“…A rapid loss in the ability of malate to inhibit PEP carboxylase has been observed (14,15), and an increase in the total enzyme activity during enzyme isolation and storage has been reported (6). Addition of malate (14,16), casein (16) or glycerol (6) (11,12) and CAM (18) plants. We have found that simple storage at low temperature is also sufficient to induce changes in the aggregation state of the CAM enzyme.…”

mentioning

confidence: 99%

Regulation of Phosphoenolpyruvate Carboxylase from Crassula argentea

Wu¹,

Wedding²

1987

Plant Physiol.

View full text Add to dashboard Cite

Phosphoenolpyruvate carboxylase in Crassulacean acid metabolism plants during the day exists in dimeric form the activity of which is strongly inhibited by malate. Enzyme purified from Crassula leaves collected during the day and stored at -70°C for 49 days shows a steady progression of change from dimer to tetramer, and this change in oligomeric state is accompanied by a decrease in the sensitivity of the enzyme to inhibition by malate. At 10 minutes preincubation of enzyme after 11 days storage-which is composed of an equilibrium mixture of dimer and tetramer-with malate causes most of the enzyme to be converted to dimer and increases the sensitivity of the enzyme to malate inhibition during assay. Preincubation with phosphoenolpyruvate shifts the equilibrium toward the tetrameric form and reduces the maximal inhibition produced by 5 millimolar malate to less than 20%. However, none of the treatments used resulted in shifting the oligomerization equilibrium completely in either direction. (Crassula argentea Thunb.) were grown in a greenhouse as described previously (17).Chemicals. The chemicals used in this study were identical with those described earlier (17, 18) and were of the highest purity commercially available.Enzyme Assay. The activity of PEP carboxylase was measured at 25°C in 1.0 ml of 50 mm Mops (pH 7.2) containing 0.15 mm NADH, 5 mM MgSO4, 10 mM NaHCO3, 5 mM PEP, and 1 IU of malate dehydrogenase (from Sigma). The reaction was started by the addition of enzyme and the oxidation of NADH was followed at 340 nm in the cell compartment of a Beckman DU-50 spectrophotometer controlled at 25°C. Kinetic parameters were determined by fitting assays at varying concentrations of PEP to the Michaelis-Menten equation modified to provide estimates of the Hill number as well as Vm and Km (17).Enzyme Purification. The enzyme was purified from day leaves collected after 4 to 5 h of light. The purification procedure was a modification ofthe method previously described (18). All steps were performed at 0 to 4°C. Leaves were homogenized in 2 volumes of 0.05 M Hepes buffer (pH 7.2), with 1 mM EDTA, 1 mM DTT and 20% (v/v) glycerol. A Polytron homogenizer was run in an ice bath at full speed for two 15 s bursts with a 15 s cooling interval. After filtering through two layers of fine nylon mesh, the homogenate was centrifuged at 5OOg for 10 min and the supernatant liquid discarded. The pellet was extracted with the extraction buffer containing 2% Triton X-1 14 but omitting glycerol, following the method of Pryde (10) for solubilizing membrane-associated proteins. After centrifugation, the material soluble in Triton X-1 14 was fractionated by ammonium sulfate precipitation, with the fraction precipitating between 35 and 60% ammonium sulfate saturation collected by centrifugation at 16,000g for 15 min and suspended in the extraction buffer without either Triton or glycerol. The preparation was then desalted using a 2 x 20 cm Sephadex G-25 column and applied to either a DEAE-cellulose

show abstract

Section: Phosphoenolpyruvate Carboxylasementioning

confidence: 99%

“…The carboxylase is also susceptible to increasing ionic strength (Manetas et al 1986, Stiborovfi and Leblovfi 1987, Wagner et al 1986 and in the presence of NaC1 it dissociates into dimers at pH7.0 or dimers and monomers at pH 8.0 (Stiborovfi and Leblovfi 1987, Wagner et al 1986. The salt-induced dissociation is also prevented by the presence of Penolpyruvate and Mg 2+ or glucose-6-phosphate (an allosteric activator) (Wagner et al 1986(Wagner et al , 1987. High protein concentrations (Wagner et al 1987, Selinioti et al 1987, McNaughton et al 1989, cosolutes (Selinioti et al 1987) and glycerol (Podestfi and Andreo 1989) also shift the equilibrium to the larger tetrameric form.…”

Section: Phosphoenolpyruvate Carboxylasementioning

confidence: 99%

“…* Data corresponding to the C 3 enzyme. 1986a,b, Wagner et al 1986Wagner et al , 1987Wagner et al , 1988 plants; NADP-dependent malic dehydrogenase from pea (Fickenscher andScheibe 1983, Edwards et al 1985) and maize (Edwards et al 1985); and the NADP-dependent malic enzyme from sugarcane (Iglesias and Andreo 1990). In most cases, the oligomeric state of these enzymes depends on ionic strength, pH, the redox state, temperature, protein concentration and the presence of cosolutes and metabolites (substrates or allosteric effectors).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Oligomeric enzymes in the C4 pathway of photosynthesis

1990

View full text Add to dashboard Cite

This review deals with the factors controlling the aggregation-state of several enzymes involved in C4 photosynthesis, namely phosphoenolpyruvate carboxylase, NAD-and NADP-malic enzyme, NADP-malic dehydrogenase and pyruvate, phosphate dikinase and its regulatory protein. All of these enzymes are oligomeric and have been shown to undergo changes in their quaternary structure in vitro under different conditions. The activity changes linked to variations in aggregation-state are discussed in terms of their putative physiological role in the regulation of C4 metabolism.

show abstract

The Ionic Strength Changes the Quaternary Structure of Phosphoenolpyruvate Carboxylase from Maize Leaves

Cited by 3 publications

References 5 publications

Higher plant phosphoenolpyruvate carboxylase

Higher plant phosphoenolpyruvate carboxylase

Regulation of Phosphoenolpyruvate Carboxylase from Crassula argentea

Oligomeric enzymes in the C4 pathway of photosynthesis

Contact Info

Product

Resources

About