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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 16, Number 2
JKCSEZ 16(2)
April 20, 1972 

 
Title
An ESR Study of Amino Acid and Protein Free Radicals in Solution. Part Ⅵ. Enzymatic Inactivation of Lysozyme in Aqueous Solution Resulting from Exposure to Ti-H2O2 System and Gamma-Irradiation
Author
Sun-Joo Hong, L. H. Piette
Keywords
Abstract
The activity change of lysozyme resulted from its exposure to Ti-H2O2 system in aqueous liquid at room temperature and to Υ-irradiation in ice at 195。K has been measured at room temperature with a Cary-14 spectrophotometer. The enzymatic activity of lysozyme which had been added to a previously flow-mixed solution of TiCl3 and H2O2 (system Ⅰ) was compared with the activity of a lysozyme-H2O2 solution after flow-mixing with TiCl3 (system Ⅱ), considering the differences between these two activity changes as the extent of the enzymatic inactivation by the involvement of OH radical reaction. The fraction of lysozyme inactivated by OH radical in the system containing 0.0025 M TiCl3-0.1 M H2O2(pH 3.5) was 13%. When the TiCl3 concentration is double (pH 3.0), the fraction of enzyme inactivated increases to 36%. The activity of the system containing 0.025 M TiCl3-0.1 M H2O2(pH 1.5) was essentially zero. The results seem to support the previous view that the production of OH radical should be proportional to TiCl3 concentration when H2O2 is present in excess. Increase in the extent of inactivation found in system Ⅰ with increasing TiCl3 concentration may be due to a pH effect. H2O2 seems to be less effective than TiCl3 in the inactivation. 1% lysozyme solution, when γ-irradiated with a total dose of 3 M rads, loses about 20% of its activity. Lowering of temperature also was found to yield a reduction in enzymatic activity.
Page
80 - 83
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