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 $Ti-H_2O_2$ System and Gamma-Irradiation

  • Hong, Sun-Joo (Department of Biochemistry and Biophysics, University of Hawaii) ;
  • Piette, L.H. (Department of Biochemistry and Biophysics, University of Hawaii)
  • Published : 1972.04.30


The activity change of lysozyme resulted from its exposure to $Ti-H_2O_2$system in aqueous liquid at room temperature and to ${\gamma}$-irradiation in ice at $195^{\circ}K$ 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 $TiCl_3$ and $H_2O_2$ (System I) was compared with the activity of a lysozyme-$H_2O_2$ solution after flow-mixing with $TiCl_3$ (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 $TiCl_3-0.1M$ $H_2O_2$ (ph 3.5) was 13%, When the $TiCl_3$ concentration is double (pH 3.0), the fraction of enzyme inactivated increases to 36%. The activity of the system containing 0.025 M $TiCl_3-0.1$ M $H_2O_2$ (pH 1.5) was essentially zero. The results seem to support the previos view that the production of OH radical should be proportional to $TiCl_3$ concentration when $H_2O_2$ is present in excess. Increase in the extent of inactivation found in system I with increasing $TiCl_3$ concentration may be due to a pH effect. $H_2O_2$ seems to be less effective than $TiCl_3$ in the inactivation. 1% lysozyme solution, when ${\gamma}$-irradiated with a total dose of 3M rads, loses about 20% of its activity. Lowering of temperature also was found to yield a reduction in enzymatic activity.



  1. Radiation Res. v.5 J. W. Hunt;J. F. Till;J. F. Williams
  2. Radiation Res. v.23 J.W. Hunt;J.F. Williams
  3. Nat'l. Acad. Sci., Nuclear Sci. Ser.. NAS-NS-43 Electron Spin Resonance and the Effect of Radiation on Biological System T. Henriksen
  4. Radiation Res. v.27 T.Henriksen
  5. Radiation Res. v.25 T.Sanner
  6. J. Chem. Phys. v.38 T.Henriksen
  7. This Journal v.15 Sun-Joo Hong;L. H. Piette
  8. This Journal v.15 Sun-Joo Hong;L. H. Piette
  9. Biochem. Biophys. Acta. v.93 Y. Hachimori;H.Horimishi;K.Kurihara;K.Shibata
  10. Amer. Chem. Soc. v.9 no.2-c L.H.Piette;G.Bulow;K.Loeffler
  11. Fundamentals of Radiobiology Z.Bacq(ed.);P. Alexander(ed.)
  12. Radiation Res., Suppl. v.4 R.A. Luse
  13. This Journal v.16 Sun-Joo Hong;L. H. Piette
  14. This Journal v.15 Sun-Joo Hong;D.E.Holmes;L.H. Piette
  15. Nature v.196 W.T.Dixon;R.O.C.Norman
  16. Biochem. Biophys. Acta. v.8 D. Shugar
  17. Korean Biochem. J. v.4-1 Sun-Joo Hong;L. H. Piette