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662067 
Journal Article 
Changes in the structure of pyruvate dehydrogenase complex induced by mono- and divalent ions 
Pawelczyk, T; Olson, MS 
1995 
Yes 
International Journal of Biochemistry and Cell Biology
ISSN: 1357-2725 
27 
5 
513-521 
The activity of pyruvate dehydrogenase complex purified from pig kidney cortex was affected by various mono- and di-valent ions and changes in ionic strength. The fluorescence emission spectrum of PDC exposed to 0.04 M ionic strength and excited at 280 nm exhibited a maximum at 334 nm; the fluorescence intensity of PDC appeared to depend upon the ionic strength and the K+ and Na+ content of the incubation buffer. Alteration of ionic strength to which the enzyme complex was exposed produced a change in the absorption of the complex at 230 nm. The presence of HPO4(2-) ions prevented changes in the UV absorption spectrum of PDC induced by the variation in ionic strength. The K+ and Na+ ions alone had no effect on the UV spectrum of PDC. Upon increasing the ionic strength to which the enzyme complex was exposed, dramatic changes in the circular dichroism (CD) pattern were observed. At 0.04 M ionic strength PDC exhibited a CD spectrum with minima at 216, 218 and 222 nm and a cross-over point at 215 nm. At 0.15 M ionic strength the CD spectrum of PDC exhibited minima at 223, 226, 228 nm and a cross- over point at 221 nm. The presence of HPO4(2-) ions prevented alterations in the CD spectrum of PDC induced by variations in ionic strength. The K+ and Na+ ions had no effect on the CD spectrum of PDC. 
Animal; Chlorides; pharmacology; Circular Dichroism; Hydrogen-Ion Concentration; Ions; Kidney Cortex; enzymology; Molecular Structure; Osmolar Concentration; Phosphoric Acids; Potassium; Pyruvate Dehydrogenase Complex; chemistry; drug effects; metabolism; Sodium; Spectrometry; Fluorescence; Spectrophotometry; Ultraviolet; Support; U.S.Gov't; P.H.S.; Swine