Abstract
In water-methanol and water-dimethylformamide (DMF) (1:1 v/v) solutions tryptophanase from E.coli retains its abilities to form a quinonoid complex with quasisubstrates and to catalyze the decomposition of S-o-nitrophenyl-L-cysteine (SOPC). Both the KM and Vmax values decrease in water-organic media. The affinities of tryptophanase for L-alanine, L-tryptophan, oxindolyl-L-alanine and indole in aqueous methanol are decreased, the effect being stronger for the more hydrophobic substances. In a water solution tryptophanase catalizes the reaction of SOPC with indole to form L-tryptophan while in water-organic solvents only decomposition of SOPC is observed.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Alanine / metabolism
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Catalysis
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Cysteine / analogs & derivatives*
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Cysteine / metabolism
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Dimethylformamide / chemistry*
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Escherichia coli / enzymology*
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Hydrogen-Ion Concentration
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Hydrolysis
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Kinetics
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Methanol / chemistry*
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Pyridoxal Phosphate / chemistry
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Solutions
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Spectrophotometry, Ultraviolet
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Stereoisomerism
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Substrate Specificity
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Tryptophan / metabolism
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Tryptophanase / chemistry
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Tryptophanase / isolation & purification
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Tryptophanase / metabolism*
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Water / chemistry
Substances
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Solutions
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Water
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Pyridoxal Phosphate
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S-o-nitrophenyl-L-cysteine
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Dimethylformamide
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Tryptophan
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Tryptophanase
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Cysteine
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Alanine
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Methanol