Effect of environmental conditions on radiation target size analyses.
Target size determinations from radiation inactivation of proteins is dependent on the physical and chemical environment of the sample during radiation exposure. Effects of temperature and physical state have already been described. Buffers, the effects of protein concentration, and the addition of small molecules are examined for several enzymes. Phosphate buffer is found to have major effects on the rate of inactivation of certain, but not all, proteins. The amount of protein in irradiated samples is significant for all enzymes studied; the nature of the specific protein used is unimportant. Neither sucrose nor other glycitols could substitute for protein in target size determinations. Certain small molecules, especially cysteamine, were effective in sparing the need for high protein levels in radiation inactivation studies of four enzyme systems.
Kempner
E S
ES
Laboratory of Physical Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Miller
J H
JH
D000110:Acetylcholinesterase / Q000097:blood / Q000528:radiation effects; D001798:Blood Proteins / Q000528:radiation effects; D002021:Buffers; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003543:Cysteamine / Q000494:pharmacology; D004789:Enzyme Activation / Q000528:radiation effects; D004910:Erythrocyte Membrane / Q000201:enzymology / Q000528:radiation effects; D005954:Glucosephosphate Dehydrogenase / Q000097:blood / Q000528:radiation effects; D005982:Glutathione Transferase / Q000097:blood / Q000528:radiation effects; D006801:Humans; D008970:Molecular Weight; D010316:Particle Size; D011506:Proteins / Q000737:chemistry* / Q000528:radiation effects*
D001798:Blood Proteins; D002021:Buffers; D011506:Proteins; D003543:Cysteamine; D005954:Glucosephosphate Dehydrogenase; D005982:Glutathione Transferase; D000110:Acetylcholinesterase