Effect of p-chloromercurybenzoate on the MDH-activity of cytosol and rat liver submitochondrial fractions in different buffers
Kirkova, M.; Russanov, E.
Acta Physiologica et Pharmacologica Bulgarica 6(1): 53-59
1980
ISSN/ISBN: 0323-9950 PMID: 7405594 Document Number: 157596
The effect of p-chloromercurybenzoate (p-CMB) on the MDH-activity of cytosol and submitochondrial fractions (matrix and inner membranes) of rat liver is studied in different buffer systems with identical pH. It is found that p-CMB has two effects on the MDH-activity, depending on the subcellular localization of the enzyme and on the type of buffer used: inhibitory (for the enzyme of the three fractions in HEPES-NaOH and potassium-phosphate buffers) and activating (for the enzyme of the submitochondrial fractions in Tris-HCI buffer). The effect of the SH-reagent on the formation and stability of enzyme-substrate complexes in the different buffers is also studied, as well as the temperature dependence of the p-CMB action on the MDH-activity of the preparations. It is found that the association of m-MDH with the inner mitochondrial membranes does not change its kinetic behaviour. The probable different conformation of the mitochondrial enzyme in the different buffer systems is discussed.