Pyruvate carboxylase from chicken liver: effects of sulfate and other anions on catalytic activity and structural parameters |
| |
| Authors: | M C Scrutton |
| |
| Affiliation: | 1. Laboratory of Food Chemistry and Technology, School of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece;2. Institute of Applied Biosciences, CERTH, Thermi, GR-570 01 Thessaloniki, Greece;1. Faculty of Civil Engineering and Architecture, Kaunas University of Technology, Studentų st. 48, LT 51367 Kaunas, Lithuania;2. Faculty of Civil Engineering, Vilnius Gediminas Technical University, Sauletekio al. 11, LT 10223 Vilnius, Lithuania;1. Department of Ocean Sciences, Memorial University, St John''s A1C 5S7, NL, Canada;2. Society for the Exploration and Valuing of the Environment (SEVE), St. Philips A1M 2B7, NL, Canada;3. Instituto de Ciencias del Mar (ICM-CSIC), Paseo Marítimo de la Barceloneta, 37-49, 08003 Barcelona, Spain;4. Stazione Zoologica Anton Dohrn (SZN), 80121 Naples, Italy;1. Center for Genomics and Systems Biology, New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates;2. Experimental Marine Ecology Laboratory, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore |
| |
| Abstract: | Sulfate ion acts as a competitive inhibitor of pyruvate carboxylase purified from chicken liver with respect to CoASAc. The Ki for SO42− is obtained as 1.0–1.3 mm at pH 7.8 and 5.4 mm at pH 7.1. The extent of cooperativity in the relationship between initial rate and SO42− concentration is minimal at very low CoASAc concentration but increases as the activator concentration is raised. However, the presence of SO42− does not alter the extent of cooperativity in the relationship between initial rate and CoASAc concentration. Inhibition by SO42− is either uncompetitive (pyruvate) or noncompetitive (MgATP2−, HCO3−, phosphate) with respect to the substrates of the pyruvate carboxylase reaction. Sulfate decreases the rate of inactivation observed when pyruvate carboxylase is incubated at 2 °C and increases the rate of inactivation caused by incubation of this biotin-enzyme with avidin. Dissociation constants calculated from these data are in reasonable agreement with the Ki obtained from initial rate studies conducted at the same pH. Several other divalent and monovalent anions also act as competitive inhibitors with respect to CoASAc and cause similar alterations in the rates of inactivation resulting from incubation at 2 °C or in the presence of avidin.The data indicate that inhibition of this pyruvate carboxylase by anions such as SO42− may be due to interaction of these ions at the CoASAc site. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
