Sensitization of the radiolytic inactivation of ribonuclease by cupric ions

Journal Article · Sat Dec 01 04:00:00 EST 1973 · Int. J. Radiat. Biol., v. 24, no. 6, pp. 561-567

DOI:https://doi.org/10.1080/09553007314551471· OSTI ID:4350161

Bisby, R H; Cundall, R B

The effect of complexed cupric ions on the radioinduced inactivation of ribonuclease in nitrous oxide saturated solutions was studied. The effect of pH on the Cu/sup 2+/RNase ratio required for the maximum degree of sensitized showed that more sites for binding became involved at higher pH. It is suggested that the variation of the inactivation efficiency with pH was due to histidine residues being involved in cupric binding to ribonuclease. At pH greater than 10, sensitization occurred through hydroxyl radical reaction with thyrosine residues, as was shown by the effect of the selective (CNS)/sub 2/-radical. Enzymatic inactivation involved formation of the Cu(III) state which oxidized an essential histidine residue. Oxygen and hydrated electrons exerted a protective effect on the cupric ion sensitized inactivation. (auth)

• Research Organization: Univ. of Nottingham, Eng.
• NSA Number: NSA-29-015839
• OSTI ID: 4350161
• Journal Information: Int. J. Radiat. Biol., v. 24, no. 6, pp. 561-567, Journal Name: Int. J. Radiat. Biol., v. 24, no. 6, pp. 561-567; ISSN IJRBA
• Country of Publication: United Kingdom
• Language: English

Related Subjects

*COPPER COMPOUNDS-- RADIOSENSITIVITY EFFECTS
*RNA-ASE-- INACTIVATION
BINDING ENERGY
BIOLOGICAL RADIATION EFFECTS
CATIONS
HISTIDINE
HYDROXYL RADICALS
N48110* --Life Sciences--Radiation Effects on Biochemicals-- In-Vitro
NITROGEN OXIDES
PH VALUE
RADIOPROTECTIVE SUBSTANCES
RADIOSENSITIVITY
RADIOSENSITIZERS
RESPONSE MODIFYING FACTORS
SATURATION
SOLUTIONS
SOLVATED ELECTRONS
TYROSINE