Abstract
WHILE developing a chemical method for the assay of ACTH by dinitrophenylation and subsequent hydrolysis with chymotrypsin, we observed that no di-DNP-seryl-tyrosine could be identified in the digestion mixture by gel filtration on ‘Sephadex G-25’ column and thin layer chromatography. This suggested that DNP-ACTH is attacked by the enzyme, not at the tyrosyl-2 peptide bond, but at other positions yielding large peptide fragments. The O-DNP derivative of tyrosine may interfere with the action of chymotrypsin on the tyrosyl peptide bond. No work seems to have been reported on the esterase activity of chymotrypsin when the phenolic group of tyrosine is blocked by alkylation or acylation. To verify our hypothesis, model substrates were synthesized in which the phenolic group of tyrosine was blocked by a DNP residue.
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References
Goodwin, T. W., Harris, J. I., and Hartley, B. S., Structure and Activity of Enzymes, 54 (Academic Press, London, 1964).
Sheehan, J. C., Goodman, M., and Hess, G. P., J. Amer. Chem. Soc., 78, 1367 (1956).
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KUNDU, N., ROY, S. Esterase Activity of Chymotrypsin on O-DNP-L-Tyrosine Ethyl Ester Substrates. Nature 226, 1171 (1970). https://doi.org/10.1038/2261171a0
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DOI: https://doi.org/10.1038/2261171a0
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