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Biomedical subjects

M Lillis

Publications and source records attributed to M Lillis.

9 recordsLinked to original sources
PubMed2001

The new navigators. Geriatric care managers forge paths for clients.

Long-term care needs are evolving in unforeseen ways. Successful aging in place is a primary concern for baby boomers and their parents. Medical advances, coupled with the complex health care delivery systems, present unique challenges for the consumer. Increasingly, the changing demographics of our society are placing new demands on these systems. Seniors and their families are taking a proactive stance, seeking health care advocates to assist them with need assessments, treatment recommendations, planning, and support services.

Aged↗
PubMed1991

Overexpression of Acetohydroxyacid Synthase from Arabidopsis as an Inducible Fusion Protein in Escherichia coli: Production of Polyclonal Antibodies, and Immunological Characterization of the Enzyme.

Acetohydroxyacid synthase (AHAS, EC 4.1.3.18) is the first enzyme unique to the biosynthesis of valine, leucine, and isoleucine. This enzyme is the target site of several classes of structurally unrelated herbicides. The conventional method of antibody production using purified protein has not been successful with this enzyme. Two separate fragments of a gene encoding a portion of the mature region of AHAS from Arabidopsis were fused with the trpE gene from Escherichia coli using the pATH1 vector. E. coli cells transformed with each respective plasmid expressed a fusion protein at levels greater than 10% of the total cell protein. The fusion protein was purified and used to immunize rabbits. Antisera obtained from the immunized rabbits immunoprecipitated AHAS activity from Arabidopsis cell free extracts. The anti-AHAS antisera reacted with a 65 kilodalton protein band in electrophoretically resolved extracts of Arabidopsis. In cross-reactivity tests, this antibody was able to immunoprecipitate AHAS activity from various plant species. Furthermore, a protein band with a molecular mass of 65 kilodaltons was detected in the crude extracts of all plant species tested on a Western blot. These results indicate that the 65 kilodalton protein represents AHAS in various plant species. The wide spectrum of cross-reactivity for the antisera supports the view that the AHAS enzyme is highly conserved across all plant species.

Journal Article↗
PubMed1990

Lac repressor-operator interaction: DNA length dependence.

The interaction of the E. coli lac operon repressor with its operator DNA has been directly examined as a function of the length of operator-containing DNA. The apparent bimolecular association rate constants were calculated as ka = (kd/KD), where the dissociation equilibrium constant, KD and the dissociation rate constant, kd, were measured by nitrocellulose filter adsorption assays. The values obtained for the overall association rate constants are compared with theoretical association rate curves for specific mechanisms. Association of the repressor with short operator containing DNA fragments (less than 70 base pairs) occurs at rates expected of three-dimensional diffusion. Our data also imply that at longer DNA lengths a combination of three-dimensional diffusion with one-dimensional sliding along with hopping and/or intersegment transfer must be involved to facilitate the repressor operator association.

Base Composition↗
PubMed1982

lac repressor-lac operator interaction: NMR observations.

We show here the changes in the NMR spectra of the Escherichia coli lac repressor when bound to isolated lac operator DNA. The observations focus on the aromatic residues--four tyrosines and a single histidine--in the amino-terminal DNA binding domain of the lac repressor. There is a good correlation between chemical shift changes seen by 19F NMR when compared with 1 H NMR of otherwise identical repressor--DNA complexes. The results suggest that the tyrosines do not intercalate in the DNA. The NMR spectral changes with similarly sized DNA fragments, not containing the lac operator DNA sequence, are different. Thus, the amino-terminal domain of the lac repressor is independently capable of discriminating between lac operator and nonspecific DNA sequences. There can be two amino-terminal fragments per operator in the specific complex.

Amino Acid Sequence↗