25] Radiation inactivation analysis of virus-mediated fusion reactions

Abstract

Publisher Summary This chapter summarizes the information obtained using radiation inactivation analysis and reviews its application to the specific problem of virus-mediated fusion. The technique of radiation inactivation analysis offers a unique means by which the function of a protein can be related to its size and structure. A radiation inactivation experiment is very simple in principle. A series of identical frozen (or lyophilized) samples are subjected to increasing levels of high-energy radiation and each sample is then assayed for the specific protein or functional property of interest. The radiation is administered either as electrons from an accelerator or as γ rays from a 60 Co or 137 Cs source. These particles are of sufficiently high energy that a single hit on a protein molecule can break several covalent bonds, thus obliterating the protein as a discrete entity and totally destroying its activity. The larger the protein, therefore, the more likely it is to be hit (and thereby inactivated) by any given dose of radiation—that is, large proteins are bigger targets than small ones. The most important parameter to be obtained from radiation inactivation analysis is the functional target size governing a particular measurable activity.