English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The three enzymatic steps in the conversion of α-ketoisovalerate to α-ketoisocaproate were examined in wild-type and in leucine auxotrophic stocks of yeast. Procedures for the reliable assay of each of the enzymatic steps in crude extracts were devised. Crude extracts of the prototrophic haploid stock catalyzed all three enzymatic steps. Examination of a series of leucine auxotrophs permitted a correlation between the three enzymatic steps and the genetic lesions affecting 10 different loci. This examination revealed that a single locus (le -6) affected primarily α-isopropylmalate synthetase, the first step in the pathway. Lesions in six loci (le -1,le -4,le -5,le -7,le -8, andle -10) lead primarily to a deficiency in the activity of the second enzyme in the pathway, α-isopropylmalate isomerase. Stocks with lesions in three loci (le -2,le -3, andle -9) were primarily blocked in the third step of the pathway, catalyzed by β-isopropylmalate dehydrogenase. The results with the mutants provide strong evidence that the pathway for leucine biosynthesis proposed by Strassman and his colleagues is the sole significant pathway in yeast.

Biosynthesis of Branched-Chain Amino Acids in Yeast: Correlation of Biochemical Blocks and Genetic Lesions in Leucine Auxotrophs