Open AccessComparison of the kinetic properties of the pyruvate dehydrogenase complex from pig kidney cortex and medulla.
Author(s) -
Tadeusz Pawełczyk,
Merle S. Olson
Publication year - 1993
Publication title -
acta biochimica polonica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.452
H-Index - 78
eISSN - 1734-154X
pISSN - 0001-527X
DOI - 10.18388/abp.1993_4817
Subject(s) - chemistry , medulla , pyruvate dehydrogenase complex , ionic strength , dephosphorylation , renal medulla , pyruvic acid , renal cortex , pyruvate kinase , cortex (anatomy) , biophysics , pyruvate dehydrogenase phosphatase , ionic bonding , biochemistry , kidney , enzyme , endocrinology , ion , biology , glycolysis , organic chemistry , neuroscience , aqueous solution , phosphatase
The activity of the pyruvate dehydrogenase complex (PDC) purified from pig kidney medulla was affected by K+, Na+, Cl-, HCO3-, HPO4(2-) 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), HPO4(2-) (10 mM) and at ionic strength of 0.15 M the S0.5 for pyruvate of PDC from medulla was 117 microM 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 microM and the enzyme was saturated at 4.5 mM pyruvate. Based on the results presented in this report it is suggested that PDC in kidney medulla may be regulated not only by a phosphorylation/dephosphorylation system and end-product inhibition but also via changes in ionic strength.