N- valine

Materials. l NH Cl, l N-Leucine, N-Glycine, N-Valine and l N-Lysine were purchased from Cambridge Isotope Laboratories (Andover, MA). l3c-C6-Glucose and H-dodecylphosphocholine were obtained from Isotec. Inc. (Miamisburg, Ohio). Unlabeled amino acids were obtained from Sigma Chemical Co. (St. Louis, MO)... 

The fraction of dose in the liver following administration of l-[ N]-valine to dogs and rhesus monkeys was 13% and 11%, respectively (34). Neither species accumulated significant amounts of label in the heart or pancreas. Tissue distribution studies in rats with L-[ N]valine yielded pancreatic relative concentrations of about 10 from 10-50 min after injection. Liver relative concentration in this interval was 1.9-2.6. 

Figure I. Relative concentration of in rat brain as a function of time foUowing intravenous injection of glutamate, L, P N]valine, and...

Stindl A. Keller U. Epimerization of the n-valine portion in the peptide chain of aciinomycin. Biochem 1994 33 9358. 

Fia. 4. Relation between the molar extinction coefficient of the nitroprusside color in water and its increase in 7 M urea for different thiols. Points from left to right are Thioglycolic acid, 8-mercapto-propionic acid (upper), homocysteine (lower) /3-mercaptoethanol (upper), cysteine (lower), coenzyme A, L-cysteinyl-n-valine, glutamyl-cysteine, L-oysteinyl-i.-valine, phenacetyl-cysteinyl-glycine, glutathione, phenacetyl-cysteinyl-D-valine. 

As with most other amino acids, the catabolism of valine is initiated by removal of its amino group, in this case to yield a-ketoisovaleric acid. L-Valine is readily susceptible to transamination, and it is slowly attacked by L-amino acid oxidase. The n-valine is readily deaminated by D-amino acid oxidase. ... 

In principle, N-NMR constitues a non-degradative method for the study of the metabolism of nitrogen-containing compounds. In this area, the incorporation of 1[ N]- valine into penicillin G was examined (B 62). 

The formula of penicillin (IV) has three asymmetric centers one corresponds to the a-carbon atom of the amino acid penicillamine (V) the second is derived from the substituted a-formyl-a -amino acid, penaldic acid (VI), while the third asymmetric center is produced by the condensation of these two components to the thiazolidine structure present in the penicillins. The penicillamine isolated from penicillin was shown to have n configuration by conversion to n-valine. Penaldic... 

A reversal of the 5 4H) 5 2H) equilibrium was established by demonstrating the presence of 4-isopropyl-2-trifluoromethyl-5(2 r)-oxazolone as an intennediate in the reaction of iV -TFA-n-valine with the methyl ester of L-valine [Eq. (35)] using gas chromatography. The resulting product is a mixture of 74% l,l- and 26% d,l-J T-TFA dipeptide methyl ester (see Section II, B, 4). 

Booth, H., B. W. Bycroft, C. M. Wels, K. Corbett, and A. P. Maloney Application of N Pulsed Fourier Transform Nuclear Magnetic Resonance Spectroscopy to Biosynthesis Studies incorporation of L-[ N]-Valine in Penicillin G. J. C. S. Chem. Commun. 1976, 110. 

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