title: Determination of the number of photoreactivating enzyme molecules per haploid Saccharomyces cells.
abstract: Two haploid radiation-sensitive mutants of Saccharomyces were studied to investigate the formation of complex between photoreactivating-enzyme and substrate after ultra-violet irradiation. Using photo-flashes, the time necessary for maximum complex formation has been determined. Within 1 min, 70 per cent of the complexes have been formed. To determine the number of photoreactivating enzyme molecules per cell, the maximum dose decrement obtained after one photo-flash was determined and corrected for the effects of non-photoreactivable lesions. The corrected maximum dose decrement was found to be identical for both strains (8-5 erg mm-2). The number of photoreactivating-enzyme molecules involved in the photorepair of nuclear DNA damage was calculated as 272 +/- 27.
mesh_terms: D002470:Cell Survival / Q000528:radiation effects; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000032:analysis*; D004307:Dose-Response Relationship, Radiation; D006238:Haploidy; D011830:Radiation Effects; D012440:Saccharomyces / Q000201:enzymology* / Q000528:radiation effects; D014466:Ultraviolet Rays
chemical_list: D004255:Deoxyribodipyrimidine Photo-Lyase