Reference

Purification and some physicochemical properties of biosynthesized L-threonine dehydratase from brewers' yeast, Saccharomyces carlsbergensis

Purification and some physicochemical properties of biosynthesized L-threonine dehydratase from brewers' yeast, Saccharomyces carlsbergensis. Dorozhko, A. I.; Kovaleva, S. V.; Rabinovich, S. E.; Smuruzhenkova, T. V.; Kagan, Z. S. (Res. Inst. Biol. Test. Chem. Compds., Kupavna, USSR). Biokhimiya (Moscow), 49(3), 370-80 (Russian) 1984. CODEN: BIOHAO.Several reagents such as 9024-34-4 is used here. ISSN: 0006-307X. DOCUMENT TYPE: Journal CA Section: 7 (Enzymes) L-Threonine dehydratase (I) was purified 4800-fold with a 34% yield; the specific activity was 110 mmol 2-oxobutyrate/mg protein/min during L-threonine dehydration (pH 7.8, 25°). The purifn. procedure included 8 steps. The mol. wt. of the I subunit was 50,000-55,000; that of native I was 300,000 as detd. by gradient polyacrylamide gel electrophoresis and gel filtration through Sephadex G-200. Native I was a hexamer made up of multiple mol. forms as was demonstrated by different methods, including ultracentrifugation. The mol. wt. of the I subunit, as calcd. from its amino acid compn., was 53,800; its partial sp. vol. was 0.737 mL/g. I catalyzed the dehydration of L-threonine and L-serine with pH optima at pH 9.5 and 9.0, resp., at satg. concn. for L-threonine. By use of the mixed substrate method, it was shown that the dehydration of both a-amino-b-hydroxy acids was catalyzed by the same enzyme. Optimal conditions for the maintenance of enzymic activity as well as the kinetic and allosteric properties of the enzyme were selected. .

Molar extinction coefficients in aqueous solutions of some amino acids

Molar extinction coefficients in aqueous solutions of some amino acids. Singh, Kulwant; Sandhu, G. K.; Kaur, Gagandeep; Lark, B. S. ( Department of Physics, Guru Nanak Dev University Amritsar, Amritsar 143005, India). Journal of Radioanalytical and Nuclear Chemistry, 253(3), 369-373 (English) 2002 Kluwer Academic Publishers. CODEN: JRNCDM. ISSN: 0236-5731. DOCUMENT TYPE: Journal CA Section: 34 (Amino Acids, Peptides, and Proteins) Section cross-reference(s): 8, 22 Mass attenuation coeffs. of amino acids viz. glycine (C2H5NO2), L-Serine (C3H7NO3), L-Threonine (C4H9NO3), L-Proline (C5H9NO2), L-Valine (C5H11NO2) and L-Phenylalanine (C9H11NO2) in aq. solns. have been detd. at 81, 356, 511, 662, 1173 and 1332 keV by the gamma-ray transmission method in a narrow beam good geometry setup. Precisely measured densities of these solns. were used for the detn. of these coeffs. which varied systematically with the corresponding changes in the concns. (g/cm3) of the solns. Molar extinction coeffs. of amino acids were then obtained at these energies and were found to be in good agreement with the theor. results. In addn., total interaction cross sections of amino acids in aq. solns. were also calcd.