Zur biologischen Wirksamkeit elastischer Kernstoesse. I. Inaktivierung von Ribonuclease durch langsame Protonen

Abstract

Extremely thin layers of ribonuclease were irradiated with slow protons and the differential inactivation cross section determined for various proton energies in the range from 0.8 to 60 keV. At higher proton energies the inactivation cross section is not strongly dependent on energy but with decreasing proton energy it decreases rapidly, reaches a sharp minimum at 1.2 keV and increases again at still smaller energies. By comparing the experimentally determined inactivation cross sections with the cross sections for energy loss in elastic nuclear collisions and in ionizations, respectively, elastic collisions were demonstrated to destroy, in fact, the enzymatic activity of ribonuclease. The energy required for an inactivation by nuclear collision is only one fourth of the energy necessary for an inactivation by ionization.