Studies on some kinetic parameters of aldolases in selected tissues of the freshwater fish (Tilapia mossambica) under the toxic impact of methyl parathion
| Autor: | K. V. Ramana Rao, Prasada Rao S. Kodavanti |
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| Rok vydání: | 1989 |
| Předmět: |
Muscle tissue
food.ingredient Lysine Methyl Parathion Toxicology food Fructose-Bisphosphate Aldolase medicine Animals Amino Acids Histidine biology Parathion Aldolase C Aldolase B Aldolase A Fishes Tilapia Metabolism Hydrogen-Ion Concentration Kinetics medicine.anatomical_structure Biochemistry biology.protein Ketoglutaric Acids Calcium |
| Zdroj: | Journal of applied toxicology : JAT. 9(6) |
| ISSN: | 0260-437X |
| Popis: | Kinetic parameters of aldolases in muscle, gill, liver and brain tissues of the teleost Tilapia mossambica were studied at sublethal concentrations with methyl parathion (MP). The pH activity profiles were optimal at pH 7.0 and 9.0 in gill, liver and brain tissues, whereas only a single peak at pH 7.0 was observed in muscle tissue of both control and MP-exposed fish. The pH 7.0-specific peak was confirmed as aldolase A and the pH 9.0-specific peak represents the tissue-specific aldolases: aldolase B in liver, aldolase C in brain and aldolase B-C in gill. It is further confirmed with the inhibitor sensitivity of aldolases at two peaks with 6 × 10−3 M ATP or AMP. The pH-based substrate-dependent kinetics of aldolases showed a variable trend. The tissue-specific activity of pH 7.0-specific aldolases showed low Km values for gill followed by muscle, liver and brain tissues, suggestive of its high enzyme-substrate affinity. During MP exposure, the Vmax values of pH 7.0-specific aldolases in muscle, gill and brain were unchanged compared to controls, but Km values were decreased. The pH 9.0-specific aldolases of gill and liver from MP-exposed fish showed decreased Km values with a slight increase in Vmax values. Effectors such as lysine, arginine and Ca2+ inhibited, while histidine, cysteine, aspartic acid and α-ketoglutaric acid elevated the activity levels of aldolases. It was concluded that the considerable enhancement in the catalytic efficiency of both the pH 7.0- and ph 9.0-specific aldolases during MP toxicity could be due to a change in the configuration of aldolases or due to a change in the intracellular environment. |
| Databáze: | OpenAIRE |
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