%0 Journal Article %A Davies, R. %T A New Factor Stimulating Invertase Production by Saccharomyces fragilis %D 1971 %J Microbiology, %V 66 %N 1 %P 37-53 %@ 1465-2080 %R https://doi.org/10.1099/00221287-66-1-37 %I Microbiology Society, %X SUMMARY: The isolation of a new factor stimulating invertase production by glucose-repressed Saccharomyces fragilis is described. If the incubation time was sufficiently long (7 h.) the amount of invertase produced was proportional to the amount of factor added. With some strains of S. fragilis invertase factor could be replaced with arginine and partially with methionine. Its composition, behaviour toward alkali, isatin, ninhydrin and fluorodinitrobenzene, and its electrophoretic properties suggest that invertase factor is the diketopiperazine derivative of arginine and proline. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-66-1-37