Summary
Kinetic data for alternative substrates of recombinant trypanothione reductase fromTrypanosoma cruzi were measured for a series ofN-substituted-L-cysteinylglycyl-3-dimethylaminopropylamides, in which the cysteineN-substituent was either a variant of the benzyloxycarbonyl group or was L-phenylalanine or L-tryptophan. Replacing the benzylic ether oxygen atom by CH2. or NH had relatively minor effects on kcat, but raised the value of Km, 4.5- and 10-fold, respectively. Similarly, relative to the carbobenzoxy group, anN-L-phenylalanyl orN-L-tryptophanyl replacement on the cysteine hardly altered kcat, but increased Km, values by 16.6 and 7.4 fold, respectively. These observations were consistent with the Km, values referring primarily to binding for this series of nonspecific substrates.
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Abbreviations
- DCC:
-
N,N′-dicyclohexylcarbodiimide
- dmapa:
-
dimethylaminopropylamine
- DMF:
-
dimethylformamide
- GR:
-
glutathione reductase
- GSSG:
-
glutathione disulphide
- GSH:
-
reduced glutathione
- T[S]2 :
-
trypanothione disulphide
- Hbt:
-
hydroxybenzotriazole
- TFA:
-
trifluoroacetic acid
- TLC:
-
thin layer chromatography
- T[SH]2 :
-
reduced trypanothione as dithiol
- TR:
-
trypanothione reductase
- Z.cys.gly.dmapa:
-
N-benzyloxycarbonyl-Lcysteinylglycyl-3-dimethylpropylamide
References
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Yuen, C.T., Garforth, J., Besheya, T. et al. Synthesis and enzymology of modifiedN-benzyloxycarbonyl-L-cysteinylglycyl-3,3-dimethylaminopropylamide disulphides as alternative substrates for trypanothione reductase fromTrypanosoma crud: Part 3. Amino Acids 17, 175–183 (1999). https://doi.org/10.1007/BF01361880
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DOI: https://doi.org/10.1007/BF01361880