Male Wistar rats of various age groups were injected daily over a period of 3 weeks with iproniazid (10 micrograms/g body wt.) and L-dihydroxyphenylalanine (L-dopa; 0.1 mg/g body wt.). On the final day 1 h before the termination of the experiment the animals were injected with L-[14C]valine (0.1 microCi/g body wt.). The specific radioactivity of the valine in the proteins of the subcellular fra...

Raman and infrared spectra of Boc-(L-Val-D-Val),-OMe [(LD-Val),], with n = 4, 6 and 8, were obtained in crystalline and solution states. Based on predictions from normal-mode calculations of a number of relevant singleand double-stranded p-helix conformations, structures were assigned for the three oligopeptides under the abovementioned conditions. In the crystalline state, all three oligopepti...

Genetic breeding of microbial amino acid producers has been done conventionally by acquiring auxotrophic mutants or regulatory mutants based on fundamental knowledge of amino acid biosynthetic pathways and their regulatory mechanisms. The conventional techniques are effective in that a number of amino acids, such as lglutamate, L-lysine, L-phenylalanine, L-threonine, larginine, L-isoleucine, L-...

A spontaneous leu-linked mutation (ilvH2015) in Escherichia coli K-12 made the strain resistant to 1 mM valine and l mM glycylvaline (Val-r) and caused the isoleucine and valine biosynthetic enzyme, acetohydroxy acid synthase, to be less sensitive to feedback inhibition by valine than the wild-type enzyme. Transfer of the ilvDAC deletion into a strain carrying ilvH2015 abolished the effect of t...

A sensitive analytical method for the analysis of acrylamide and other electrophilic agents in water has been developed. The amino acid L-valine served as a nucleophilic trapping agent. The method was applied to the analysis of acrylamide in 0.2-1 mL samples of drinking water or Millipore-filtered water, brewed coffee, or water extracts of snuff. The reaction product, N-(2-carbamoylethyl)valine...

Growth assays and nitrogen balance trials were conducted in an attempt to estimate requirements for threonine, isoleucine, valine and leucine. Weanling kittens were fed a basal purified diet containing 27% crystalline L-amino acids and 4,700 kcal metabolizable energy per kilogram diet. Based upon rate and efficiency of growth, and upon urinary nitrogen excretion, estimated requirements for thre...

Exchange of the native Corynebacterium glutamicum promoter of the aceE gene, encoding the E1p subunit of the pyruvate dehydrogenase complex (PDHC), with mutated dapA promoter variants led to a series of C. glutamicum strains with gradually reduced growth rates and PDHC activities. Upon overexpression of the l-valine biosynthetic genes ilvBNCE, all strains produced l-valine. Among these strains,...