The physiological role of the isoenzymes of lactate dehydrogenase in potatoes

Planta
H Asker, D D Davies

Abstract

Four of the five isoenzymes of lactate dehydrogenase present in potato tubers have been isolated and their kinetic properties examined. The pyruvate-reductase activity of isoenzyme-4 is greatly reduced at low pH, the affinity for both pyruvate and NADH is reduced and ATP has a stronger inhibitory effect. If the design properties of an enzyme dictate a high affinity for substrates, then the Km values for lactate, glyoxylate and NAD are consistent with an oxidative role for isoenzyme-4. The same considerations do not permit a conclusion about the physiological role of isoenzymes-1 to-3. However, an overview of the kinetic properties of these isoenzymes indicates that isoenzyme-1 is best adapted for the role of pyruvate reductase. Consideration of the relationships between kinetic constants and electrophoretic mobilities of the isoenzymes, leads us to predict that isoenzyme-5 is well adapted for a role in the oxidation of lactate or glyoxylate. The lactate dehydrogenase of potato leaves appears to consist prodominantly of an isoenzyme with the same mobility as isoenzyme-2 of the tubers and the two isoenzymes are probably identical. The kinetic properties of this isoenzyme are consistent with roles in either oxidation or reduction.

References

Oct 1, 1972·The Biochemical Journal·D D Davies, S Davies
Aug 1, 1967·Analytical Biochemistry·A A Dietz, T Lubrano
Jun 14, 1968·Annals of the New York Academy of Sciences·N O KaplanJ Admiraal
Jul 15, 1973·Comparative Biochemistry and Physiology. B, Comparative Biochemistry·M I SiegelB Rosenberg-Bassin
Mar 5, 1971·Nature
Mar 3, 1971·Nature: New Biology·M Rosenberg
Apr 1, 1967·Journal of Theoretical Biology·A L Koch
Nov 1, 1980·The Biochemical Journal·E Poerio, D D Davies
May 1, 1983·Plant Physiology·D D Davies, H Asker
Jan 1, 1967·Annual Review of Biochemistry·W W Cleland

Citations

Feb 1, 1997·Phytochemistry·N Sugiyama, N Taniguchi
Sep 13, 2001·International Clinical Psychopharmacology·E WhiskeyD Taylor
Aug 22, 2013·Behavioural Pharmacology·Elizete M ReisRoselei Fachinetto
Nov 1, 1989·Archives of Biochemistry and Biophysics·K TihanyiJ P Thirion

Related Concepts

Adenosine Triphosphate
Isoenzymes
Lactate Dehydrogenase
NADH
Oxidation
Potato
Dysplastic Nevus
Glyoxylate
Cerebellar Tuber
Plant Leaves

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