Citrate and succinate uptake by potato mitochondria

Journal Article · Sun Apr 01 04:00:00 EST 1979 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.63.4.591· OSTI ID:5639235

Jung, D W; Laties, G G

Potato mitochondria, in the absence of respiration, have a very low capacity for uptake by exchange with endogenous anions, taking up only 2.4 nanomoles citrate and 2.0 nanomoles succinate per milligram protein. Maximum citrate uptake of over 17 nanomoles per milligram protein occurs in the presence of inorganic phosphate, a dicarboxylic acid, and an external energy source (NADH), conditions where net anion accumulation proceeds, mediated by the interlinking of the inorganic phosphate, dicarboxylate, and tricarboxylate carriers. Maximum succinate uptake in the absence of respiratory inhibitors requires only added inorganic phosphate. Compounds which inhibit respiration (antimycin), the exchange carriers (mersalyl and benzylmalonate), or the establishment of the membrane proton motive force (uncouplers) reduce substrate accumulation. A potent inhibitor of the citrate carrier in animal mitochondria, 1,2,3-benzenetricarboxylic acid, does not inhibit citrate uptake in potato mitochondria. Citrate uptake is reduced by concurrent ADP phosphorylation and this reduction is sensitive to oligomycin. The initiation of state 3 after a 3-minute substrate state results in a reduction of the steady-state of citrate uptake by approximately 50%. Accumulation of succinate initially is inhibited by increasing sucrose concentration in the reaction medium from 50 to 400 millimolar. Limited substrate uptake is one of the factors responsible for the often observed depressed initial state 3 respiration rates in many mitochondrial preparations. Since nonlimiting levels of substrate in the matrix cannot be attained by energy-independent exchange, a dependence on respiration for adequate uptake results. Substrate limitation therefore occurs in the matrix for the period of time needed for energy-dependent accumulation of nonlimiting levels.

• Research Organization: Univ. of California, Los Angeles
• DOE Contract Number: EY-76-S-03-0034
• OSTI ID: 5639235
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 63:4; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADP
ANIONS
ANTIBIOTICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON 14
CARBON ISOTOPES
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHARGED PARTICLES
CHEMICAL REACTIONS
CITRATES
COENZYMES
DICARBOXYLIC ACIDS
DRUGS
EVEN-EVEN NUCLEI
FOOD
INHIBITION
IONS
ISOTOPES
LIGHT NUCLEI
MEMBRANE TRANSPORT
MITOCHONDRIA
NAD
NUCLEI
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHOSPHORYLATION
POTATOES
PROTEINS
RADIOISOTOPES
RESPIRATION
SUCCINIC ACID
TRICARBALLYLIC ACID
TUBERS
VEGETABLES
YEARS LIVING RADIOISOTOPES