Accumulation of L-Asparagine by Saccharomyces cerevisiae X-2180
| Autor: | Anthony H. Rose, Malcolm E. Gregory, Michael H. J. Keenan |
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| Rok vydání: | 1982 |
| Předmět: | |
| Zdroj: | Microbiology. 128:2557-2562 |
| ISSN: | 1465-2080 1350-0872 |
| DOI: | 10.1099/00221287-128-11-2557 |
| Popis: | SUMMARY: At concentrations up to 1 mM, l-asparagine was accumulated by Saccharomyces cerevisiae X-2180 at 30 °C against a concentration gradient. Values for K T and V max were, respectively, 3.5 x 10-4 M and 33 nmol (mg dry wt)-1 min-1. At concentrations below 0.1 mM, a convex curve was obtained on a Woolf-Hofstee plot, possibly indicating the presence of two l-asparagine-binding sites. Autoradiograms of extracts of organisms that had accumulated labelled l-asparagine revealed only one spot with an R F value identical with that of l-asparagine. Four mutant strains lacking the ability to synthesize the general amino acid permease system grew and accumulated l-asparagine at similar rates to the parent. The rate of accumulation of l-asparagine from a 0.2 mM solution was greatest at pH 4.5, with the decrease in accumulation rate greater at values below than above 4.5. l-Glutamine, l-histidine, l-methionine, l-threonine and l-tryptophan caused appreciable inhibition of the rate of l-asparagine accumulation. With the exception of l-methionine, the inhibition caused by these amino acids was competitive. Several other amino acids, including d-asparagine and l-aspartic acid, caused little or no inhibition of l-asparagine accumulation. |
| Databáze: | OpenAIRE |
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