A comparison of the association of yeast phosphoglycerate mutase (EC2.7.5.3) with that of haemoglobin. An ultracentrifuge study

Publisher Website
Google Scholar
Abstract
Previous work showed that yeast phosphoglycerate mutase (EC 2.7.5.3) has a MW of between 107,000-110,000. Preliminary examination showed that at dilutions less than 0.1 g/l the enzyme dissociated into its subunits. This dissociation was quantitatively examined by both equilibrium and velocity centrifugation. The mathematical analysis of the equilibrium records was tested against human oxyhemoglobin in a variety of ionic strengths and at 2 temperatures. The estimated L2,4 (interaction coefficient) for oxyhemoglobin generally agreed with published values except at 6.degree. C in 0.9 M-NaCl, when it was 2.5 times larger than the published value. Statistical analysis of ultracentrifugal-equilibrium experiments showed that the predominant reaction for phosphoglycerate mutase was monomer .dblarw. tetramer, to give an L1,4 of 40.3 .+-. 23.4 (SD)13.cntdot.g-3 at 20.degree. C. Decreasing the temperature decreased the association to give an enthalpy of between 40-60kJ/mol. Analysis of velocity experiments carried out with concentrations varying from 0.3-17 g/l gave an L1,4 of 31113.cntdot.g-3. Incorporating errors from estimating .hivin.S20,w into the analysis showed that this estimate could range from 893-14213.cntdot.g-3. The concentration-dependence of .hivin.S20,w was 0.95 l.cntdot.g-1 and .**GRAPHIC**. for the tetramer was 66.9 ps. These results are discussed in relation to the activity of the enzyme.