PHYSICOCHEMICAL PARAMETERS AND SUBUNIT COMPOSITION OF YEAST PHOSPHOFRUCTOKINASE
PHYSICOCHEMICAL PARAMETERS AND SUBUNIT COMPOSITION OF YEAST PHOSPHOFRUCTOKINASE
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DOI：
10.1111/j.1432-1033.1977.tb11954.x
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发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
HOFMANN, E
中科院分区：
文献类型：
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作者：
KOPPERSCHLAGER, G;BAR, J;HOFMANN, E
The properties of proteolytically non-modified phosphofructokinase [EC 2.7.1.11] from baker''s yeast were investigated by means of hydrodynamic, electrophoretic and chemical methods. The sedimentation coefficient shows a linear dependence on the protein concentration down to 0.01 mg/ml. The sedimentation coefficient was determined to be .**GRAPHIC**. = 20.81 S. At concentrations of the enzyme at less than 0.01 mg/ml a significant decrease of this value was found. The partial specific volume of the enzyme as determined by 3 different methods at 20.degree. C is v2 = 0.742 ml/g. From equilibrium sedimentation a MW of 835,000 .+-. 32,000 was calculated for the native enzyme. Amino acid analysis of the enzyme was performed and the number of half-cystine residues determined as 11/100,000 g is in good agreement with the number of titratable -SH groups after denaturation of the enzyme. The subunit MW was determined by applying equilibrium sedimentation in the presence of sodium dodecylsulfate. Taking into account that 0.37 g of dodecylsulfate is bound per g of the enzyme protein as found by equilibrium dialysis, a subunit MW of 104,000 was calculated. This value is about 15% smaller than that obtained by gel electrophoresis in the presence of sodium dodecylsulfate. Evidently, yeast phosphofructokinase seems to be octameric. Limited proteolysis in the presence of proteinase B from yeast was investigated by following the alterations of the sedimentation coefficient, the MW, and the subunit pattern of the enzyme. During partial proteolytic degradation the MW of the native enzyme decreases by about 230,000. This diminution is in accordance with the difference in the MW per subunit if an octameric composition is considered.
