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Biochemistry, Biophysics, and Structural Biology Commons

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Retrospective Theses and Dissertations

1994

Biochemistry

Articles 1 - 4 of 4

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

Dethiolation Of Protein Mixed-Disulfides , Che-Hun Jung Jan 1994

Dethiolation Of Protein Mixed-Disulfides , Che-Hun Jung

Retrospective Theses and Dissertations

The dithiol proteins, glutaredoxin, thioredoxin, and protein disulfide isomerase, were examined as dethiolases (i.e., reductases for protein mixed-disulfides) by studying the specificity and reactivity for an S-glutathiolated protein mixture. The 35S-glutathiolated protein mixture was prepared from 35S-labeled rat hepatocytes by diamide treatment. Dethiolation of individual 35S-labeled proteins was analyzed by combining SDS-PAGE and autoradiography. The dithiol proteins greatly enhanced dethiolation rates and could completely dethiolate all of the S-glutathiolated proteins. The dethiolation rate for individual proteins by each dithiol protein was compared and glutaredoxin was the most effective for every S-glutathiolated hepatocyte protein. When testing the reduction of insulin ...


Expression, Purification, Characterization, And Site-Directed Mutagenesis Of Phosphorylase Kinase [Upsilon] Subunit , Chi-Ying F. Huang Jan 1994

Expression, Purification, Characterization, And Site-Directed Mutagenesis Of Phosphorylase Kinase [Upsilon] Subunit , Chi-Ying F. Huang

Retrospective Theses and Dissertations

The overall aim was to elucidate the substrate specificity and regulatory properties of the catalytic subunit of phosphorylase kinase (PhK) to better understand how this enzyme works. I have expressed the PhK [gamma] subunit (full-length and seven truncated forms) in E. coli. One of the truncated forms of [gamma], [gamma][subscript]1-300 has a 2-fold higher specific activity than the full-length [gamma], suggesting that an autoinhibitory domain(s) is located at the C-terminus of [gamma], [gamma][subscript]301-386. The truncated [gamma][subscript]1-300 purified to homogeneity has several properties similar to full-length [gamma], including its substrate specificity and metal ion ...


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 ...