Articles
FLAVOCYTOCHROME B2 ACTIVITY IN SATUREJA HORTENSIS L. LEAVES
Article number
853_45
Pages
369 – 378
Language
English
Abstract
Satureja hortensis, an annual herb belonging to the Lamiaceae family, has been used since Antiquity in the Mediterranean and Indo-Iranian regions as culinary herb as well as medicinal plant.
Although the medicinal value of S. hortensis has been recognized for thousands of years by tradition, and recently by modern experimental procedures, information on the basic aspects of the physiology and enzymology of the plant is only scarcely available.
In this study, flavocytochrome b2 activity was investigated in an extract obtained from S. hortensis leaves.
Flavocytochrome b2, or L-(+)-lactate ferricytochrome c oxidoreductase (EC.1.1.2.3), is involved in respiration and energy production.
It transfers electrons from lactate to cytochrome c (as a physiological electron acceptor) or to other electron acceptors such as potassium ferricyanide.
Flavocytochrome b2 activity was measured in the extract by following spectrophotometrically, at 420 nm, the reduction of potassium ferricyanide in the presence of lactate and EDTA. PH activity profile exhibited one peak at 9.5 and a shoulder at 8.0. Kinetics parameters, determined at pH optima were as follows: a) with lactate as the varied substrate, apparent Km and Vmax were, respectively, 2.6 mM and 0.5 μM.min-1.mg prot-1 at pH 8.0, and 6 mM and 0.95 μM.min-1.mg prot-1 at pH 9.5; b) with potassium ferricyanide as the varied substrate, apparent Km and Vmax were, respectively, 23 μM and 0.3 μM.min-1.mg prot-1 at pH 8.0, and 40 μM and 0.65 μM.min-1.mg prot-1 at pH 9.5. Malate was a competitive inhibitor of the activity with an IC50 of 13 mM at pH 8.0 and 27 mM at pH 9.5. Electrophoresis of the extract in polyacrylamide gel under non-denaturing conditions revealed two bands after activity staining in the presence of lactate and tetrazolium blue.
Data suggest that at least two isoenzymes of flavocytochrome b2 are present in S. hortensis leaves.
Although the medicinal value of S. hortensis has been recognized for thousands of years by tradition, and recently by modern experimental procedures, information on the basic aspects of the physiology and enzymology of the plant is only scarcely available.
In this study, flavocytochrome b2 activity was investigated in an extract obtained from S. hortensis leaves.
Flavocytochrome b2, or L-(+)-lactate ferricytochrome c oxidoreductase (EC.1.1.2.3), is involved in respiration and energy production.
It transfers electrons from lactate to cytochrome c (as a physiological electron acceptor) or to other electron acceptors such as potassium ferricyanide.
Flavocytochrome b2 activity was measured in the extract by following spectrophotometrically, at 420 nm, the reduction of potassium ferricyanide in the presence of lactate and EDTA. PH activity profile exhibited one peak at 9.5 and a shoulder at 8.0. Kinetics parameters, determined at pH optima were as follows: a) with lactate as the varied substrate, apparent Km and Vmax were, respectively, 2.6 mM and 0.5 μM.min-1.mg prot-1 at pH 8.0, and 6 mM and 0.95 μM.min-1.mg prot-1 at pH 9.5; b) with potassium ferricyanide as the varied substrate, apparent Km and Vmax were, respectively, 23 μM and 0.3 μM.min-1.mg prot-1 at pH 8.0, and 40 μM and 0.65 μM.min-1.mg prot-1 at pH 9.5. Malate was a competitive inhibitor of the activity with an IC50 of 13 mM at pH 8.0 and 27 mM at pH 9.5. Electrophoresis of the extract in polyacrylamide gel under non-denaturing conditions revealed two bands after activity staining in the presence of lactate and tetrazolium blue.
Data suggest that at least two isoenzymes of flavocytochrome b2 are present in S. hortensis leaves.
Authors
L. Arzi, E. Keyhani, J. Keyhani
Keywords
cellular respiration, electron transfer, enzymatic activity, gel electrophoresis, isoenzymes, lactate dehydrogenase, Lamiaceae, malate
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