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D M Schneider

Publications and source records attributed to D M Schneider.

8 recordsLinked to original sources
PubMed1992

Fast internal main-chain dynamics of human ubiquitin.

The fast internal dynamics of human ubiquitin have been studied by the analysis of 15N relaxation of backbone amide nitrogens. The amide 15N resonances have been assigned by use of heteronuclear multiple-quantum spectroscopy. Spin lattice relaxation times at 60.8 and 30.4 MHz and the steady-state nuclear Overhauser effect at 60.8 MHz have been determined for 67 amide 15N sites in the protein using two-dimensional spectroscopy. These data have been analyzed in terms of the model free treatment of Lipari and Szabo [Lipari, G., & Szabo, A. (1982) J. Am. Chem. Soc. 104, 4546-4559]. The global motion of the protein is shown to be isotropic and is characterized by a correlation time of 4.1 ns rad-1. The generalized order parameters (S2) of backbone amide N-H vectors in the globular region of the protein range from 0.5 to 0.95. No apparent correlation between secondary structure and generalized order parameters is observed. There is, however, a strong correlation between the magnitude of the generalized order parameters of a given N-H vector and the presence of hydrogen bonding of the amide hydrogen or its peptide bond associated carbonyl. Using a chemical shift tensor breadth of 160 ppm, the N-H vectors of peptide linkages participating in one or more hydrogen bonds to the main chain show an average generalized order parameter of 0.80 (SD 0.06), while those amide NH of peptide linkages free of hydrogen-bonding interactions with the main chain show an average order parameter of 0.69 (SD 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1992

Characterization of the secondary structure of calmodulin in complex with a calmodulin-binding domain peptide.

The interaction between calcium-saturated chicken calmodulin and a peptide corresponding to the calmodulin-binding domain of the chicken smooth muscle myosin light chain kinase has been studied by multinuclear and multidimensional nuclear magnetic resonance methods. Extensive 1H and 15N resonance assignments of calmodulin in the complex have been obtained from the analysis of two- and three-dimensional nuclear magnetic resonance spectra. The assignment of calmodulin in the complex was facilitated by the use of selective labeling of the protein with alpha-15N-labeled valine, alanine, lysine, leucine, and glycine. These provided reference points during the main-chain-directed analysis of three-dimensional spectra of complexes prepared with uniformly 15N-labeled calmodulin. The pattern of nuclear Overhauser effects (NOE) seen among main-chain amide NH, C alpha H, and C beta H hydrogens indicates that the secondary structure of the globular domains of calmodulin in the complex closely corresponds to that observed in the calcium-saturated state of the protein in the absence of bound peptide. However, the backbone conformation of residues 76-84 adopts an extended chain conformation upon binding of the peptide in contrast to its helical conformation in the absence of peptide. A sufficient number of NOEs between the globular domains of calmodulin and the bound peptide have been found to indicate that the N- and C-terminal regions of the peptide interact with the C- and N-terminal domains of calmodulin, respectively. The significance of these results are discussed in terms of recently proposed models for the structure of calmodulin-peptide complexes.

Amino Acid Sequence↗
PubMed1992

Combined myopia and astigmatism surgery. Review of 350 cases.

Between February 1985 and December 1987, 350 eyes had combined radial keratotomy and transverse keratotomy surgery. All procedures were performed by the same surgeon. The number and length of the radial and transverse incisions were varied according to the surgeon's clinical judgment based on his personal experience and the nomograms developed by Thornton. Our results showed that 93% of the eyes had 20/40 or better uncorrected visual acuity at the last follow-up visit. The data indicate that quantifiably predictable results can be achieved with this procedure and that results appear stable up to five years after surgery in 80% of the documented cases. There was a tendency toward increasing effect of the transverse incisions in 20% of cases studied. This seems to correlate well with previous studies measuring long-term results with radial incisions for myopia.

Astigmatism↗
PubMed1991

Structure of the smooth muscle myosin light-chain kinase calmodulin-binding domain peptide bound to calmodulin.

The interaction between the peptide corresponding to the calmodulin-binding domain of the smooth muscle myosin light-chain kinase and (Ca2+)4-calmodulin has been studied by multinuclear and multidimensional nuclear magnetic resonance methods. The study was facilitated by the use of 15N-labeled peptide in conjunction with 15N-edited and 15N-correlated 1H spectroscopy. The peptide forms a 1:1 complex with calcium-saturated calmodulin which is in slow exchange with free peptide. The 1H and 15N resonances of the bound have been assigned. An extensive set of structural constraints for the bound peptide has been assembled from the analysis of nuclear Overhauser effects and three-bond coupling constants. The backbone conformation of the bound peptide has been determined using these constraints by use of distance geometry and related computational methods. The backbone conformation of the peptide has been determined to high precision and is generally indicative of helical secondary structure. Nonhelical backbone conformations are seen in the middle and at the C-terminal end of the bound peptide. These studies provide the first direct confirmation of the amphiphilic helix model for the structure of peptides bound to calcium-saturated calmodulin.

Amino Acid Sequence↗
PubMed1991

Implementation of the main chain directed assignment strategy. Computer assisted approach.

A computer-assisted procedure has been developed to apply the main chain directed (MCD) assignment strategy to the analysis of 1H NMR spectra of proteins. The underlying mathematical foundation of this procedure, termed MCDPAT, is presented. MCDPAT is based upon the expanded library of MCD patterns defined previously (A.J. Wand and S.J. Nelson. 1991. Biophys. J. 59:1101-1112), and has been evaluated with both simulated and experimental data from the protein ubiquitin. The influence of the precision, spectral variation, and inherent degeneracy upon the design of the procedure is explored. Several approaches have been taken to overcome the uncertainty introduced by these variables. These include a hierarchical approach to both primary pattern recognition and subsequent construction of MCD-defined units of secondary structure. It is shown that the MCDPAT procedure, in conjunction with automated statistically based spectral analysis, leads to the successful MCD assignment of the protein ubiquitin. The implications and limitations of this approach are discussed.

Hydrogen↗
PubMed1987

The high-molecular-weight proteins of bovine brain plain synaptic vesicles.

High molecular mass polypeptides (Mr greater than 100,000) of plain synaptic vesicles from bovine cerebral cortex were separated using porous polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Four major bands, of Mr 262,000, 249,000, 216,000, and 173,000, were resolved. Investigations into the membrane association of the Mr 216,000 and 173,000 proteins by means of solubilization experiments and Sepharose 4B chromatography indicate that the former is a peripheral protein and the latter is more firmly attached, possibly an integral protein. Finally, the Mr 216,000 protein was shown to be highly enriched in synaptic vesicles compared to other brain subfractions. It thus appears to be specifically associated with synaptic vesicles and therefore may have an important role specific to synaptic vesicle function or structure.

Animals↗
PubMed1976

Porcelain shoulder adaptation using direct refractory dies.

Eleven direct refractory dies were made from separate polysulfide rubber impressions of two Dentoform teeth which had been prepared for porcelain-fused-to-gold veneer crowns with labial porcelain shoulders. Porcelain veneer crowns were built and fired directly on the dies, following the manufacturer's instructions and using a common laboratory technique. The finished crowns were seated on the Dentoform teeth, and the porcelain-tooth adaptation was measured with a micrometer eyepiece in a dissecting microscope. In general, the study indicated that by use of a direct refractory die, the porcelain adaptation of an average porcelain shoulder veneer crown could be made to fall within the tolerances of a clinically acceptable gold margin (39 mu).21 The crown could likewise be made to adapt closer than the normal thickness of cement film may allow (20 to 40 mu).22 However the adaptation of many crowns was more uneven than the above statements would tend to indicate. The study also showed that with great care and a limited number of firings, margins of a lesser thickness than a piece of 0.001 inch (25.4 mu) platinum foil could be attained. There appears to be promise in the use of a direct refractory die material. However, more studies are needed to overcome some of the problems in the technique described.

Crowns↗