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C A Michaels

Publications and source records attributed to C A Michaels.

5 recordsLinked to original sources
PubMed1992

Correlation of tryptophan fluorescence intensity decay parameters with 1H NMR-determined rotamer conformations: [tryptophan2]oxytocin.

While the fluorescence decay kinetics of tyrosine model compounds [Laws, W. R., Ross, J. B. A., Wyssbrod, H. R., Beechem, J. M., Brand, L., & Sutherland, J. C. (1986) Biochemistry 25, 599-607] and the tyrosine residue in oxytocin [Ross, J. B. A., Laws, W. R., Buku, A., Sutherland, J. C., & Wyssbrod, H. R. (1986) Biochemistry 25, 607-612] can be explained in terms of heterogeneity derived from the three ground-state chi 1 rotamers, a similar correlation has yet to be directly observed for a tryptophan residue. In addition, the asymmetric indole ring might also lead to heterogeneity from chi 2 rotations. In this paper, the time-resolved and steady-state fluorescence properties of [tryptophan2]oxytocin at pH 3 are presented and compared with 1H NMR results. According to the unrestricted analyses of individual fluorescence decay curves taken as a function of emission wavelength and a global analysis of these decay curves for common emission wavelength-independent decay constants, only three exponential terms are required. In addition, the preexponential weighting factors (amplitudes) have the same relative relationship (weights) as the 1H NMR-determined chi 1 rotamer populations of the indole side chain. 15N was used in heteronuclear coupling experiments to confirm the rotamer assignments. Inclusion of a linked function restricting the decay amplitudes to the chi 1 rotamer populations in the individual decay curve analyses and in the global analysis confirms this correlation. According to qualitative nuclear Overhauser data, there are two chi 2 populations. Depending upon the degree of correlation between chi 2 and chi 1, there may be from three to six side-chain conformations for the tryptophan residue. The combined fluorescence and NMR results are consistent with a rotamer model in which either (i) the chi 2 rotations are fast compared to the fluorescence intensity decay of the tryptophan residue, (ii) environmental factors affecting fluorescence intensity decay properties are dominated by chi 1 interactions, or (iii) the chi 2 and chi 1 rotations are highly correlated.

Amino Acid Sequence↗
PubMed1973

Studies on the action of nalidixic acid in the yeast Saccharomyces cerevisiae.

The effect of the antibiotic nalidixic acid on macromolecular metabolism in the yeast Saccharomyces cerevisiae has been studied. It was found that, upon the addition of nalidixic acid to a logarithmically growing culture, there is a transient inhibition of total cell ribonucleic acid, deoxyribonucleic acid, and protein synthesis, after which the cells show an almost complete recovery. In addition, there is no preferential inhibition of yeast mitochondrial deoxyribonucleic acid synthesis.

Centrifugation, Density Gradient↗
PubMedDate not supplied

A neuropsychological approach to the assessment of adults with learning disabilities in vocational rehabilitation.

A description of cognitive, academic, and personality characteristics of adults with learning disabilities (LD) referred for services through the state/federal vocational rehabilitation system is presented. This study builds on the work of Minskoff, Hawks, Steidle, and Hoffmann (1989) and validates their conclusions that, as a group, adults with LD participating in vocational rehabilitation are homogeneous relative to other groups of adults with LD. By taking a neuropsychological approach to the assessment process, the current study further subdivided the assessment categories described by Minskoff et al. This approach assumes that the vocational competence of adults with learning disabilities may be better understood in terms of their visual and auditory perception; verbal and nonverbal reasoning; verbal and mixed (verbal/nonverbal) learning; linguistic and nonlinguistic memory; semantic, expressive, and receptive language; basic and conceptual academic skills; and social and psychological adjustments. The data analyses identify several potential patterns of psychosocial and neuropsychological strengths and weaknesses that may be important in vocational rehabilitation efforts.

Adult↗
PubMedDate not supplied

The right stuff.

The right health care, at the right intensity, over the right period of time, in the right setting, at the right cost, with the right outcome--that's what Burlington Industries wants for its employees, dependents, retirees and bottom line. Burlington's Director of Personnel Administration, who is responsible for health and safety programs, tells how the Company is working toward these ambitious goals.

Cost Control↗