The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase.
The effect of chaotropic anions was studied on processes that constitute the chloroplast fructose-1,6-bisphosphatase reaction, i.e. enzyme activation and catalysis. The specific activity of chloroplast fructose-1,6-bisphosphatase was enhanced by preincubation with dithiothreitol, fructose 1,6-bispho...
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todo:paper_00219258_v262_n33_p16171_Stein2023-10-03T14:22:55Z The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. Stein, M. Wolosiuk, R.A. anion dithiothreitol fructose bisphosphatase article chloroplast enzyme activation enzymology kinetics metabolism plant Anions Chloroplasts Dithiothreitol Enzyme Activation Fructose-Bisphosphatase Kinetics Plants The effect of chaotropic anions was studied on processes that constitute the chloroplast fructose-1,6-bisphosphatase reaction, i.e. enzyme activation and catalysis. The specific activity of chloroplast fructose-1,6-bisphosphatase was enhanced by preincubation with dithiothreitol, fructose 1,6-bisphosphate, Ca2+, and a chaotropic anion. When chaotropes were ranked in the order of increasing concentrations required for maximal activation they followed a lyotropic (Hofmeister) series: SCN- less than Cl3C-COO- less than ClO4- less than I- less than Br- less than Cl- less than SO4(2-). On the contrary, salts inhibited the catalytic step. The stimulation of chloroplast fructose-1,6-bisphosphatase by chaotropic anions arose from a decrease of the activation kinetic constants of both fructose 1,6-bisphosphate and Ca2+; on the other hand, in catalysis neutral salts caused a decrease of kcat because the S0.5 for both fructose 1,6-bisphosphate and Mg2+ remained unaltered. The molecular weight of chloroplast fructose-1,6-bisphosphatase did not change after the activation by incubation with dithiothreitol, fructose 1,6-bisphosphate, Ca2+, and a chaotrope; consequently, the action of these modulators altered the conformation of the enzyme. Modification in the relative position of aromatic residues of chloroplast fructose-1,6-bisphosphatase was detected by UV differential spectroscopy. In addition, the concerted action of modulators made the enzyme more sensitive to (a) trypsin attack and (b) S-carboxymethylation by iodoacetamide. These results provide a new insight on the mechanism of light-mediated regulation of chloroplast fructose-1,6-bisphosphatase; concurrently to the action of a sugar bisphosphate, a bivalent cation, and a reductant, modifications of hydrophobic interactions in the structure of chloroplast fructose-1,6-bisphosphatase play a crucial role in the enhancement of the specific activity. Fil:Stein, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Wolosiuk, R.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00219258_v262_n33_p16171_Stein |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
anion dithiothreitol fructose bisphosphatase article chloroplast enzyme activation enzymology kinetics metabolism plant Anions Chloroplasts Dithiothreitol Enzyme Activation Fructose-Bisphosphatase Kinetics Plants |
| spellingShingle |
anion dithiothreitol fructose bisphosphatase article chloroplast enzyme activation enzymology kinetics metabolism plant Anions Chloroplasts Dithiothreitol Enzyme Activation Fructose-Bisphosphatase Kinetics Plants Stein, M. Wolosiuk, R.A. The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. |
| topic_facet |
anion dithiothreitol fructose bisphosphatase article chloroplast enzyme activation enzymology kinetics metabolism plant Anions Chloroplasts Dithiothreitol Enzyme Activation Fructose-Bisphosphatase Kinetics Plants |
| description |
The effect of chaotropic anions was studied on processes that constitute the chloroplast fructose-1,6-bisphosphatase reaction, i.e. enzyme activation and catalysis. The specific activity of chloroplast fructose-1,6-bisphosphatase was enhanced by preincubation with dithiothreitol, fructose 1,6-bisphosphate, Ca2+, and a chaotropic anion. When chaotropes were ranked in the order of increasing concentrations required for maximal activation they followed a lyotropic (Hofmeister) series: SCN- less than Cl3C-COO- less than ClO4- less than I- less than Br- less than Cl- less than SO4(2-). On the contrary, salts inhibited the catalytic step. The stimulation of chloroplast fructose-1,6-bisphosphatase by chaotropic anions arose from a decrease of the activation kinetic constants of both fructose 1,6-bisphosphate and Ca2+; on the other hand, in catalysis neutral salts caused a decrease of kcat because the S0.5 for both fructose 1,6-bisphosphate and Mg2+ remained unaltered. The molecular weight of chloroplast fructose-1,6-bisphosphatase did not change after the activation by incubation with dithiothreitol, fructose 1,6-bisphosphate, Ca2+, and a chaotrope; consequently, the action of these modulators altered the conformation of the enzyme. Modification in the relative position of aromatic residues of chloroplast fructose-1,6-bisphosphatase was detected by UV differential spectroscopy. In addition, the concerted action of modulators made the enzyme more sensitive to (a) trypsin attack and (b) S-carboxymethylation by iodoacetamide. These results provide a new insight on the mechanism of light-mediated regulation of chloroplast fructose-1,6-bisphosphatase; concurrently to the action of a sugar bisphosphate, a bivalent cation, and a reductant, modifications of hydrophobic interactions in the structure of chloroplast fructose-1,6-bisphosphatase play a crucial role in the enhancement of the specific activity. |
| format |
JOUR |
| author |
Stein, M. Wolosiuk, R.A. |
| author_facet |
Stein, M. Wolosiuk, R.A. |
| author_sort |
Stein, M. |
| title |
The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. |
| title_short |
The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. |
| title_full |
The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. |
| title_fullStr |
The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. |
| title_full_unstemmed |
The effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. |
| title_sort |
effect of chaotropic anions on the activation and the activity of spinach chloroplast fructose-1,6-bisphosphatase. |
| url |
http://hdl.handle.net/20.500.12110/paper_00219258_v262_n33_p16171_Stein |
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