PMID: 1247Nov 1, 1975

The conformational oscillation of delta-chymotrypsin involvement of methionine-192

European Journal of Biochemistry
C GhélisB Labouesse

Abstract

In delta-chymotrypsin the reactivity of methionine-192 towards p-nitrophenacyl bromide is strongly reduced when the alpha-amino group of isoleucine-16 has been acetylated. Since acetylation of isoleucine-16 brings delta-chymotrypsin to a conformation similar to its alkaline one this suggests that methionine-192 should present an impaired reactivity in the alkaline conformation of the protein. It is indeed observed that its chemical reactivity as a function of pH depends on the ionization state of the alpha-amino group of isoleucine-16 (pKapp 9 at 15 degrees C) as does the structure of the enzyme. Reciprocally, after chemical reaction of methionine-192 with hydrogen peroxide, isoleucine-16 presents a slower rate of reaction with fluorescamine than when methionine-192 is free. As a result of methionine-192 oxidation the apparent pK of the alkaline transition is shifted from 9 to about 11 at 15 degrees C. This is reflected in the disappearance of the lag phase previously observed for the initial activity of the enzyme when it is incubated at alkaline pH [Eur. J. Biochem. (1973) 39,293-300]. The absence of chemical reactivity of methionine-192 in the alkaline state of the enzyme is confirmed by the appearance of a lag phase in the ...Continue Reading

References

Feb 12, 1970·Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences·G P HessG McConkey
Mar 1, 1973·Archives of Biochemistry and Biophysics·P BöhlenS Udenfriend
Nov 1, 1973·European Journal of Biochemistry·J R Garel, B Labouesse
Jul 16, 1974·Biochemistry·J R GarelB Labouesse
May 1, 1971·Canadian Journal of Biochemistry·A KuroskyT Hofmann
Nov 1, 1969·Biochemistry·D S SigmanE R Blout
Feb 14, 1969·Journal of Molecular Biology·J McConnG P Hess
Mar 19, 1971·Biochemical and Biophysical Research Communications·H Kaplan
Mar 29, 1967·Journal of the American Chemical Society·D S Sigman, E R Blout
May 13, 1967·Nature·B W MatthewsD M Blow
Apr 1, 1965·The Biochemical Journal·J R KNOWLES
Apr 1, 1955·Biochimica Et Biophysica Acta·G W SCHWERT, Y TAKENAKA

Citations

Jun 1, 1964·Clinica Chimica Acta; International Journal of Clinical Chemistry·T W DONKERLO
Sep 1, 1967·European Journal of Biochemistry·J Labouesse, M Gervais
Apr 2, 1979·Molecular and Cellular Biochemistry·G R Ainslie, K E Neet

Related Concepts

Avazyme
Chymotrypsinogen beta
Circular Dichroism, Vibrational
Hydrogen-Ion Concentration
Alloisoleucine
Pedameth
Nitrophenols
Optical Rotation
Plasma Protein Binding Capacity
Protein Conformation

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