Effects of the proline analog L-thiazolidine-4-carboxylic acid on proline metabolism
The effect of various proline analogs on proline oxidation in mitochondria isolated from etiolated barley (Hordeum vulgare) shoots was investigated. Of the analogs tested, only L-thiazolidine-4-carboxylic acid (T4C) was an effective inhibitor. T4C (1 millimolar) inhibited proline (10 millimolar) -dependent O/sub 2/ uptake an average of 67%. T4C was also oxidized to some degree (12.9 nanoatoms oxygen per minute per milligram protein for 10 millimolar). The effect of T4C on the oxidation of other mitochondrial substrates was also tested. T4C inhibited ..delta../sup 1/-pyrrolidine-5-carboxylic acid-dependent oxygen uptake slightly (13%), the oxidation of malate plus pyruvate even less (6%), and stimulated the oxidation of succinate (+11%), exogenous NADH (+19%), and citrate (+20%). Thus, inhibition by T4C in mitochondria is relatively specific to proline oxidation. T4C was found to inhibit proline dehydrogenase and not the transport of proline into the matrix. The effect of T4C on proline metabolism in detached green barley leaves was investigated. T4C inhibited proline oxidation in turgid leaves, increasing the proline content of these leaves slightly. In wilted leaves (that are synthesizing proline rapidly), T4C inhibited proline synthesis, which resulted in a decrease in the proline content of the leaves. ..delta../sup 1/-pyrrolidine-5-carboxylic acid reductase (the last enzyme in proline synthesis) was not inhibited by T4C, and thus T4C's influence is prior to that step of the synthetic pathway. T4C had no influence on the incorporation of proline into protein.
- Research Organization:
- Iowa State Univ., Ames
- DOE Contract Number:
- AC02-82ER12028
- OSTI ID:
- 6595071
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 74:2; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINES
AMINO ACIDS
AZOLES
BARLEY
BIOLOGICAL EFFECTS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CEREALS
CHEMICAL REACTIONS
ENZYME INHIBITORS
GRAMINEAE
GRASS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
LEAVES
METABOLISM
MITOCHONDRIA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOIDS
OXIDATION
PHYSIOLOGY
PLANTS
PROLINE
PYRROLES
PYRROLIDINES
THIAZOLES