Does oxygen enhance the radiation-induced inactivation of penicillinase. Progress report, December 1, 1979-November 30, 1980

Technical Report · Tue Jan 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/5414499· OSTI ID:5414499

Samuni, A.; Kalkstein, A.; Czapski, G.

The radiation-induced inactivation of penicillinase in dilute aqueous solutions buffered with phosphate was studied, by examining enzyme radiosensitivity in the presence of various gases (He, O/sub 2/, H/sub 2/, N/sub 2/O, N/sub 2/O + O/sub 2/). The introduction of either N/sub 2/O or O/sub 2/ was found to reduce the radiodamage. On the other hand H/sub 2/ or N/sub 2/O + O/sub 2/ gas-mixture enhanced the radiosensitivity. In the presence of formate and oxygen, no enzyme inactivation was detected. The results indicated that the specific damaging efficiency of H atoms is almost four-fold higher than that of OH radical; therefore in phosphate buffer, where more than half of the free radicals are H atoms, it is the H radicals that are responsible for the majority of the damage. The superoxide radicals appeared to be completely inactive and did not contribute toward enzyme inactivation. Oxygen was shown to affect the radiosensitivity in two ways. On one side, it protected by converting e/sup -//sub aq/ and H radicals into harmless O/sub 2//sup -/ radicals. On the other side it increased the inactivation by enhancing the damage brought about by OH radicals (OER = 2.8). In the present case the oxygen effect of protection exceeded that of sensitization, thus giving rise to a moderate overall protection effect.

• Research Organization: Hebrew Univ., Jerusalem (Israel)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: AC02-76EV03221
• OSTI ID: 5414499
• Report Number(s): DOE/EV/03221-62
• Country of Publication: United States
• Language: English

Related Subjects

560111* -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AQUEOUS SOLUTIONS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CHALCOGENIDES
CRYOGENIC FLUIDS
DATA
DATA FORMS
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENZYME ACTIVITY
ENZYMES
EXPERIMENTAL DATA
FLUIDS
GAMMA RADIATION
HELIUM
HYDROGEN
HYDROLASES
HYDROXYL RADICALS
IN VITRO
INACTIVATION
INFORMATION
IONIZING RADIATIONS
IRRADIATION
ISOLATED VALUES
MIXTURES
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN
OXYGEN COMPOUNDS
OXYGEN ENHANCEMENT RATIO
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
RARE GASES
SOLUTIONS
SUPEROXIDE RADICALS