Radiation Sensitivity of Enzymes in Wet and in Dry Yeast Cells

Abstract

The sensitivity to ionizing radiation has been determined for coenzyme A and the enzymes invertase and alcohol dehydrogenase (ADH) in wet and in dry yeast cells. The sensitivity wet versus dry was about 2 to 1 for invertase, 20 to 1 for ADH, and 100 to 1 for coenzyme A. These ratios make sense qualitatively if it is assumed that the difference between the wet and the dry sensitivities is caused by the migration of chemically active intermediates formed by the radiations acting on water in the wet cells. ADH is an order of magnitude more sensitive to water radicals than is invertase, which explains its larger sensitivity when wet. Coenzyme A, on the other hand, is very sensitive to indirect action, but very insensitive to direct effect because of its small size, and has the greatest ratio of sensitivities from wet to dry.