Energy-linked adenosine diphosphate accumulation by corn mitochondria. General characteristics and effect of inhibitors
Corn mitochondria show respiration-linked net accumulation of (/sup 3/H)ADP in the presence of phosphate and magnesium, especially if the formation of ATP is blocked with oligomycin. Inhibition of ADP-ATP exchange by carboxyatractyloside also activates ADP accumulation, and addition of carboxyatractyloside or palmitoyl-coenzyme A to oligomycin-blocked mitochondria produces additional ADP uptake. With carboxyatractyloside the accumulated ADP is phosphorylated to ATP. With oligomycin, only a little ATP is formed. Millimolar concentrations of ADP are required for maximum uptake, and the K/sub m/ (3.77 millimolar) for ADP translocation is independent of whether oligomycin or carboxyatractyloside is used. This is not true for ADP concentrations in the 0.05 to 0.25 millimolar range. Accumulated (/sup 3/H)ADP rapidly exchanges with unlabeled AMP, ADP, or ATP, but not with other diphosphate nucleotides or 2 millimolar substrate anions. (/sup 3/H)AMP is not accumulated, but (/sup 3/H)ATP is accumulated to about one-half the extent of (/sup 3/H)ADP. Tricarboxylate substrates inhibit ADP net uptake, and inhibition by citrate is competitive with K/sub i/ = 10 millimolar. The evidence suggests the presence of a pathway, carboxyatractyloside-insensitive and different from the translocase, which operates to maintain adenine nucleotides in the matrix.
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- DOE Contract Number:
- EY-76-S-02-0790
- OSTI ID:
- 5518423
- Journal Information:
- Plant Physiol.; (United States), Vol. 64:2
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
MAIZE
METABOLISM
ADENOSINE
KREBS CYCLE
MAGNESIUM
MITOCHONDRIA
OXIDOREDUCTASES
PHYSIOLOGY
RESPIRATION
ALKALINE EARTH METALS
CELL CONSTITUENTS
CEREALS
ELEMENTS
ENZYMES
GRAMINEAE
GRASS
METALS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANOIDS
PLANTS
RIBOSIDES
560303* - Chemicals Metabolism & Toxicology- Plants- (-1987)
550200 - Biochemistry
550500 - Metabolism
553001 - Agriculture & Food Technology- Tracer Techniques- (-1987)