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Comparison of the kinetic properties of the pyruvate dehydrogenase complex from pig kidney cortex and medulla

100%

Pawelczyk T., Olson M. S.

Acta Biochimica Polonica

1993

tom 40

nr 3

The activity of the pyruvate dehydrogenase complex (PDC) purified from pig kidney medulla was affected by K+, Na+, CI", HCO3"", HP042" and changes in ionic strength. Increased ionic strength influenced the activity of PDC from medulla by decreasing the Vmax and S0.5 for pyruvate and increasing the Hill coefficient. The magnitude of these changes was smaller than the corresponding changes for PDC purified from the cortex. In the presence of K+ (80 mM), Na+ (20 mM), Cl~ (20 mM), HCO3" (20 mM), HPO42" (10 mM) and at ionic strength of 0.15 M the S0.5 for pyruvate of PDC from medulla was 117 nM and the enzyme complex was saturated by 1.1 mM pyruvate. Under these conditions the S0.5 for pyruvate of PDC derived from cortex was 159 nM and the enzyme was saturated at 4.5 mM pyruvate.

The dependence of electrophoretic and spectroscopic properties of the pyruvate dehydrogenase complex on mono- and divalent ions

80%

Pawelczyk T., Easom R. A., Olson M. S.

Acta Biochimica Polonica

1994

tom 41

nr 1

The effects of various mono- and divalent ions on the pyruvate dehydrogenase complex (PDC) were investigated. To determine the radius of PDC under various conditions a two-dimensional agarose gel electrophoresis technique was used. The radius of PDC cross-linked with glutaraldehyde at ionic strength 0.04 M was calculated to be 22.0 ± 0.1 nm. The presence of K+, Na+ or HPO4 prevented changes in electromobility and of the calculated radius of PDC induced by alteration in ionic strength. The fluorescence emission spectra of PDC depended on the ionic strength and monovalent cations. The fluorescence intensity of PDC increased in the presence of 80 mM K+, and decreased in the presence of 80 mM Na+ with no shift in the emission maximum wavelength. Changes in the ionic strength to which PDC was exposed resulted in alteration of the UV absorption spectra in the 230 nm region. These alterations were prevented by HPO42- , whereas N+ or K+ ions had no effect on the UV absorption spectrum of PDC.

Ograniczanie wyników

2 Acta Biochimica Polonica

2 Olson M. S.

2 Pawelczyk T.

1 Easom R. A.

1 1994

1 1993

Wyniki wyszukiwania

Comparison of the kinetic properties of the pyruvate dehydrogenase complex from pig kidney cortex and medulla

The dependence of electrophoretic and spectroscopic properties of the pyruvate dehydrogenase complex on mono- and divalent ions