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Biochemistry, Biophysics, and Structural Biology Commons

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Retrospective Theses and Dissertations

1994

Biochemistry

Biophysics

Articles 1 - 2 of 2

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Biochemical Characterization Of Plant Biotin-Containing Enzymes , Tomás Alberto Diez Jan 1994

Biochemical Characterization Of Plant Biotin-Containing Enzymes , Tomás Alberto Diez

Retrospective Theses and Dissertations

3-Methylcrotonyl-CoA carboxylase has been purified and characterized from maize leaves. The enzyme is composed of two subunits, a biotin-containing polypeptide of 80 kDa, and a nonbiotin-containing polypeptide of 58 kDa. The native molecular weight of the holoenzyme is estimated at 853,000. The enzyme probably has an [alpha][subscript]6[beta][subscript]6 configuration. The kinetic constants for the substrates of 3-methylcrotonyl-CoA and its pH optimum were determined. The enzyme is allosterically activated by Mg[superscript]2+ and nonessentially activated by monovalent cations. The enzyme is strongly inhibited by acetoacetyl-CoA and by arginyl and sulfhydryl modifying reagents;The effect of ...


Structure And Function Of Unmodified E. Coli Valine-Trna , Dongxian Yue Jan 1994

Structure And Function Of Unmodified E. Coli Valine-Trna , Dongxian Yue

Retrospective Theses and Dissertations

The effects of nucleoside modifications on E. coli tRNA[superscript]Val structure have been probed by imino [superscript]1H NMR. The NMR data shows that the structure of in vitro transcribed (unmodified) and native (modified) tRNA[superscript] Val are very similar in 15 mM Mg[superscript]2+. Temperature dependence of the spectra reveals that nucleoside modifications stabilize tertiary interactions between T and D loops. On removal of Mg[superscript]2+, unmodified tRNA[superscript] Val undergoes remarkable structural changes which are not observed in native tRNA[superscript] Val. There is near total disruption of the D stem and of tertiary interactions ...