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At least 217 records · Page 12Linked to original sources
PubMed1983

Solution conformation of asparagine-linked oligosaccharides: alpha(1-6)-linked moiety.

The solution conformation is presented for representatives of each of the major classes of asparaginyl oligosaccharides. In this report the conformation of the alpha(1-6)-linked moiety is described. The conformational properties of these glycopeptides were determined by high-resolution 1H nuclear magnetic resonance in conjunction with potential energy calculations. The NMR parameters that were used in this analysis were chemical shifts and nuclear Overhauser enhancements. Potential energy calculations were used to evaluate the preferred conformers available for the different linkages in glycopeptides and to draw conclusions and to draw conclusions about the behavior in solution of these molecules. For all classes, identical conformations were found for the 6-arm except for the torsional angle, omega, about the C5-C6 bond of the alpha 1-6 linkage. For high mannose and hybrid structures omega was found to be -60 degrees, for bisected biantennary complex structures omega was 180 degrees, and for complex biantennary structures averaging between -60 degrees and 180 degrees occurs.

Asparagine↗
PubMed1979

Complex factorial structure of Ellis' Irrational Beliefs.

Previous research with a newly developed children's scale for measuring Ellis' constructs with regard to irrational beliefs showed that while the scale clearly reflected theoretically predicted developmental trends, the internal consistency reliability of the overall 11-item scale was relatively low (.56). This low internal consistency suggested that the 11 items were in fact heterogeneous and were not measuring a single, univocal, construct. An exploratory factor analysis was performed on the responses of 788 fifth-through thirteenth-grade students. Results of the Alpha factor and analysis clearly indicate that the scale is multifaceted, i.e., comprised of four orthogonal, interpretable factors. Estimates of internal consistency reliabilities for the separate factors, when corrected for length, revealed that each of the new factors was more reliable than the full scale score in this sample. Potential revisions of the scale, as well as cautions for its use in clinical applications on its present form are discussed.

Adolescent↗
PubMed1976

Fine structure of complex ocelli of a cubomedusan, Tamoya bursaria Haeckel.

The retina of the distal and proximal lens-bearing complex ocelli are composed of pigmented sensory cells and long pigmented cells. A ciliary sheath from each sensory cell, together with the processes of long pigmented cells, extends through the vitreous layer as far as the capsule that envelops the lens. Each ciliary sheath has several ballon-like swellings and the ciliary microtubules, arranged in the 9+2 pattern in the proximal part, are markedly disorganized distally in the swollen parts, out of which extends most of the microvilli in the vitreous layer. It is suggested that some of the microvilli may originate in vesicles that are constricted off from the surface of the pigmented sensory cells. Closely packed microvilli run in parallel in short bundles. In addition to characteristic junctions between sensory cells, junctions that are presumably synaptic and, of a new type in coelenterates, are observed between sensory cells and nerve endings.

Animals↗
PubMed1986

The relationship between signal response selectivity and the functional structure of complex retinal neural networks.

In this paper we simulate the simultaneous responses of 45 neurones within a hypothetical retina to a variety of spatio-temporal signals. Our results demonstrate how specific convergent and divergent excitatory and inhibitory connections are sufficient to determine signal response selectivity of specific ganglion cells and so delimit the known types of center-surround receptive fields.

Animals↗
PubMed1987

Mitochondrial plasmid DNAs of broad bean: nucleotide sequences, complex secondary structures, and transcription.

Three circular plasmid DNA molecules of 1704, 1695 and 1476 nucleotide pairs from broad bean mitochondria (mt-plasmids 1-3) have been sequenced. Within a highly homologous segment of mt-plasmid 1 and 2 are found a series of six directly repeated, inverted repeat sequences, separated by unique sequences. Mt-plasmid 3 contains a series of four inverted repeat sequences, unrelated to the inverted repeat sequences of mt-plasmids 1 and 2. Two RNA molecules of about 440 and 320 nucleotides that are complementary to mt-plasmid 2 were detected. Mapping of 5' and 3' termini of these complementary RNA molecules indicated that all transcription from mt-plasmid 2 occurs within a 441 nucleotide region of the molecule. Evidence for transcription of mt-plasmids 1 and 3 was not found.

Base Sequence↗
PubMed1992

Flow patterns of blood cells in the retinal capillaries. Retinal capillary flow patterns.

We present a new technique for retinal blood cell angiography which was used to investigate flow patterns of blood cells in the retinal capillary net of normal cats. Capillary paths were defined to be the path taken by the labelled blood cells from the terminal arteriole to the entry point into a collecting venule. We were able to define two types of capillary paths. The 'simple' paths were minimally coiled and had a high blood cell flux. The 'complex' paths were coiled, structurally complex and had a low blood cell flux in comparison to the simple paths of the same eye. A simultaneous fluorescein angiogram was performed to reveal the complete anatomy of the capillary net in which the functional paths exist. The possibility that such flow patterns exist in the human retina should be considered.

Animals↗
PubMed1991

X-Ray structure of the antibiotic bacitracin A.

Bacitracins are a group of widely used peptide antibiotics. There has been interest in determining the three-dimensional structure of the bacitracins. However, solution studies indicate significant flexibility in their structure and to date native bacitracins have resisted attempts at crystallisation despite considerable efforts over a number of years by several groups. Here we report the first three-dimensional X-ray structure of a bacitracin, complexed to a subtilisin proteinase. X-Ray diffraction data were collected using synchrotron radiation in combination with the Image Plate Scanner system. The complex structure including two enzymes, two bacitracins, 220 water molecules and two Ca2+ ions was refined by restrained least-squares to a crystallographic R factor ( = sigma [[Fo-Fc]]/sigma [Fo]]) of 16.3% at 2.0 A.

Amino Acid Sequence↗
PubMed1992

Three-dimensional structure of a recombinant variant of human pancreatic secretory trypsin inhibitor (Kazal type).

A modified version of the human pancreatic trypsin inhibitor (PSTI), generated in a protein-design project, has been crystallized in spacegroup P4(3) with lattice constants a = 40.15 A, c = 33.91 A. The structure has been solved by molecular replacement. Refinement of the structure by simulated annealing and conventional restrained least-squares yielded for 8.0 to 2.3 A data a final R-value of 19.1%. Differences to the known structures of porcine PSTI complexed with trypsinogen and modified human PSTI complexed with chymotrypsinogen occur at the flexible N-terminal part of the molecule. These differences are influenced by crystal packing, as are low temperature factors for the binding loop. The geometry of the binding loop is similar to the complexed structures.

Amino Acid Sequence↗
PubMed1984

The mouse Lyt-2/3 antigen complex--II. Structural analysis of the subunits.

Surface- or biosynthetically labeled Lyt-2/3 antigens were isolated from cell lysates by immunoprecipitation and affinity chromatography with a monoclonal antibody. Tryptic digests of the individual subunits of 37,000, 32,000 and 28,000 apparent mol. wts were analysed by reverse-phase high-performance liquid chromatography and by two-dimensional peptide mapping. The results indicate that the 37,000 and 32,000 mol. wt components are structurally very similar whereas the 28,000 mol. wt component appears as a different molecule.

Animals↗
PubMed1992

Synthesis and characterization of N-methyliminodiacetato trans-R,R-, trans-S,S-, and cis-1,2-diaminocyclohexane platinum (IV) complexes: crystal structure of chloro(trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato) platinum(IV) chloride.

The compounds, chloro(trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato)platinum(IV) chloride, chloro(trans-S,S-1,2-diaminocyclohexane)(N-methyliminodiacetato) platinum(IV) chloride, and chloro(cis-1,2-diaminocyclohexane)(N-methyliminodiacetato)platinum (IV) chloride, were prepared and characterized by elemental analysis, IR, and 195Pt NMR. The crystal structure of one of these three compounds, chloro(trans-R,R-1,2-diaminocyclohexane) (N-methyliminodiacetato) platinum(IV) chloride, was determined by x-ray single crystal diffraction. This compound is particularly interesting because the 1,2-diaminocyclohexane (DACH) ring is in a twist-boat configuration rather than the chair configuration previously reported for other DACH platinum compounds. The crystal structure consists of two independent cations and anions, with all atoms between these two independent molecules (except those in the chiral DACH) related by a pseudo-inversion center. Both platinum atoms have slightly distorted octahedral coordination, with angles ranging from 81.8 to 100.8 degrees. Crystallographic details: space group P2(1) (monoclinic); a = 19.864(5) A, b = 7.026(2) A, c = 12.446(3) A, beta = 106.64(2) degrees; Z = 4; R = 0.036 for 2333 reflections.

Cyclohexanes↗
PubMed1980

Complex molecular structure of the gene coding for rat ceruloplasmin.

The distribution of ceruloplasmin-coding sequences among the fragments of rat nuclear DNA obtained after the complete digestion with seven restriction endonucleases (EcoRI, BamHI, BspI, HindIII, KpnI, BglII and XhoI) was studied using highly specific cDNA probes. Although only a single copy of this gene per rat haploid genome was detected in DNA-cDNA hybridization in solution, the number of restriction fragments carrying the sequences of ceruloplasmin (CP) gene varied from two to five, depending upon the enzyme used, and their total length was several times higher than the minimal length of CP-coding gene, as deduced from the size of mRNA (2.3 Md for double-stranded DNA). The partial double stranded DNA transcript of ceruloplasmin mRNA coding for about 70% of its length (from 3'-end) does not contain recognition sites for some restriction endonucleases generating multiple fragments of CP gene in cellular DNA. These data are consistent with a split pattern of CP gene which seems to consist of several exons and introns. The partial protection from S1 nuclease of discrete fragments of full-length cDNA after annealing with high molecular weight nuclear RNA is consistent with this assumption and seems to be an indication that exons and introns are joined into a functional unit coding for high mol wt. CP pre-mRNA.

Animals↗