TY - JOUR
T1 - Multiple control mechanisms for succinate dehydrogenase in mitochondria
AU - Gutman, M.
AU - Kearney, Edna B.
AU - Singer, T. P.
N1 - Funding Information:
the increased CoQ 10H2/CoQ 10 ratio). Such a mechanism might provide a rapid regulation of this key step in the Krebs cycle. AC K NOW LEDG ME NTS This research was supported by grants from the American Cancer Society (P-531) and the U. S. Public Health Service (HE 10027).
PY - 1971/8/6
Y1 - 1971/8/6
N2 - Succinate dehydrogenase (SD) in intact, respiring mitochondria undergoes activation and deactivation in response to the metabolic state of the mitochondria. Highest SD activity is observed in state 4 and lowest in state 2 or in the presence of uncouplers, while in state 3 the level of activation is intermediate and varies with the nature of the substrate. Transition from the active to inactive (unactivated) state of SD occurs in mitochondria with a lower energy of activation (10 Kcal/mole) than in soluble or membrane preparations (33 to 36 Kcal/mole). In addition to activation by succinate and CoQ10H2, the enzyme in mitochondria is uniquely activated by ATP (or a compound in equilibrium with it), a process which has not been previously observed in submitochondrial particles and is oligomycin-insensitive. In tightly coupled mitochondria reversible activation by all these agents may occur concurrently, but experimental conditions are described to study the action of each type of activator independently.
AB - Succinate dehydrogenase (SD) in intact, respiring mitochondria undergoes activation and deactivation in response to the metabolic state of the mitochondria. Highest SD activity is observed in state 4 and lowest in state 2 or in the presence of uncouplers, while in state 3 the level of activation is intermediate and varies with the nature of the substrate. Transition from the active to inactive (unactivated) state of SD occurs in mitochondria with a lower energy of activation (10 Kcal/mole) than in soluble or membrane preparations (33 to 36 Kcal/mole). In addition to activation by succinate and CoQ10H2, the enzyme in mitochondria is uniquely activated by ATP (or a compound in equilibrium with it), a process which has not been previously observed in submitochondrial particles and is oligomycin-insensitive. In tightly coupled mitochondria reversible activation by all these agents may occur concurrently, but experimental conditions are described to study the action of each type of activator independently.
UR - http://www.scopus.com/inward/record.url?scp=0015212974&partnerID=8YFLogxK
U2 - 10.1016/S0006-291X(71)80114-6
DO - 10.1016/S0006-291X(71)80114-6
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AN - SCOPUS:0015212974
VL - 44
SP - 526
EP - 532
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
SN - 0006-291X
IS - 3
ER -