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At least 235 records · Page 13Linked to original sources
PubMed1977

Structural analysis of the ridge count data of Australian Europeans using multivariate analysis.

Multivariate analyses are used to study the structural patterns of ridge counts of fingers. There is a significant difference between the ridge counts of two hands, chiefly due to the first and fourth fingers. There is asymmetry in the covariance matrix of the ridge counts. The correlations between fingers are significant and the decrease in correlation with increasing distance between fingers is not significant.

Australia↗
PubMed1990

Engineering a heavy atom derivative for the X-ray structure analysis of cyclodextrin glycosyltransferase.

Based on a preliminary structural model of cyclodextrin glycosyltransferase from Bacillus circulans (EC 2.4.1.19), Ser428 and Ser475 of the enzyme were mutated to cysteines in order to produce suitable heavy atom derivatives. Mutant Ser475----Cys could not be expressed as protein. Mutant Ser428----Cys was expressed in Escherichia coli and purified. It crystallized isomorphously and gave rise to a mercury derivative that improved the electron density map. The structural results show that the new mercury-binding site is in a pocket at the protein surface.

Bacillus↗
PubMed1992

The S-layer of Caulobacter crescentus: three-dimensional image reconstruction and structure analysis by electron microscopy.

The regular surface protein structure (S-layer) of Caulobacter crescentus was analyzed by electron microscopy and three-dimensional image reconstruction to a resolution of 2 nm. Projections showed that the S-layer is an array of ring structures, each composed of six subunits that are arranged on a lattice with p6 symmetry. Three-dimensional reconstructions showed that the ring subunits were approximately rod-shaped structures and were perpendicular to the plane of the array, with a linker arm emanating from approximately the middle of the rod, accounting for the connections between the rings. The calculated subunit mass was ca. 100 kDa, very close to the size of RsaA (the protein known to be at least the predominant species in the S-layer) predicted from the DNA sequence of the rsaA gene. The core region of the rings creates an open pore 2.5 to 3.5 nm in diameter. The size of the gaps between the neighboring unit cells is in the same range, suggesting a uniform porosity predicted to exclude molecules larger than ca. 17 kDa. Attempts to remove membrane material from S-layer preparations with detergents revealed that the structure spontaneously rearranged into a mirror-image double layer. Negative-stain and thin-section electron microscopy examination of colonies of C. crescentus strains with a mutation in a surface molecule involved in the attachment of the S-layer showed that shed RsaA protein organized into large sheets. The sheets in turn organized into stacks that tended to accumulate near the upper surface of the colony. Image reconstruction indicated that these sheets were also precise mirror-image double layers, and thickness measurements obtained from thin sections were consistent with this finding. The sheets were absent when these mutant strains were grown without calcium, supporting other data that calcium is involved in attachment of the S-layer to a surface molecule and perhaps in subunit-subunit interactions. We propose that when the membrane is removed from S-layer fragments by detergents or the attachment-related surface molecule is absent, the attachment sites of the S-layer align precisely to form a double layer via a calcium interaction.

Bacterial Outer Membrane Proteins↗
PubMed1976

Shapes of carcinogenic benz[alpha]anthracenes: an x-ray crystal structure analysis of 12-methylbenz[alpha]anthracene.

The crystal structure of the moderately active carcinogen 12-methylbenz[alpha]anthracene (12-MBA) has been determined by application of direct methods to X-ray single-crystal diffraction data. Least-squares refinement to a residual R = 0.09 over 929 independent reflections enabled carbon positions to be established with apparent e.s.d.s. of atomic coordinates about 0.008 A. Deviation from planarity is exemplified by the 15.5 degrees inclination of the benz ring (A) to the anthracene nucleus and by the 0.89 A distance of the methyl carbon out of the best plane through the whole benzanthracene nucleus. Comparison with the structure of the highly carcinogenic 7,12-dimethylbenz[alpha]anthracene (7,12-DMBA), and with the recently solved structures of the weak carcinogen 1-MBA and the extremely weak carcinogen 1,12-DMBA, shows a close similarity in the anthracene parts; in 1-MBA, and 1,12-DMBA, the phenanthrenic K-region bond is close to 1.34 A and the M-region bond about 1.38 A. In 12-MBA, overcrowding in the 'bay' region causes the central anthracene ring C and the benz ring A each to be bent about 10 degrees in opposite directions from the phenanthrenic B ring, much as in 1-MBA and 7,12-DMBA, but less than in 1,12-DMBA; the 12-methyl carbon lies about the same distance (0.55 A) above the anthracene plane in 12-MBA as in 1,12-MBA and 7,12-DMBA.

Benz(a)Anthracenes↗
PubMed1988

[X-ray crystallographic studies of diclofenac-sodium--structural analysis of diclofenac-sodium tetrahydrate].

The crystal structure of the hydrate of the antiphlogistic drug diclofenac sodium was determined to explain the unusual dissolution behaviour in ethyl acetate. The compound crystallizes in the monoclinic space group P2(1)/m with a = 9.464(2), b = 39.405(7), c = 9.972(3) A und beta = 90.74(2) degrees. The unit cell contains two symmetry independent formula units (C14H10Cl2NO2)-Na+.3,94 H2O. There are molecule layers and sodium-water layers which show order-disorder phenomena.

Crystallization↗
PubMed1990

The structural analysis of a levan produced by Streptococcus salivarius SS2.

The structure of a water-soluble levan produced by Streptococcus salivarius SS2 has been determined by means of various chemical and instrumental methods. Methylation and periodate oxidation studies demonstrate that the levan is comprised of D-fructofuranosyl backbone residues linked beta-(2----6) (about 70%) with beta-(2----1) branches (about 30%). 13C-N.m.r. spectral analysis of the polymer is consistent with the structure determined by chemical means.

Carbohydrate Sequence↗
PubMed1995

Structural analysis of recombinant von Willebrand factor produced at industrial scale fermentation of transformed CHO cells co-expressing recombinant furin.

Thorough analysis of multimer composition and molecular structure of recombinant von Willebrand factor (r-vWF) produced by recombinant CHO cells demonstrated r-vWF to be more intact and less proteolytically degraded than plasma-derived vWF (pd-vWF) [B. Fischer et al. (1994) FEBS Lett. 351, 345-348]. In contrast to pd-vWF, r-vWF preparations consisted of pro-vWF (vWF containing covalently attached propeptide) as well as mature vWF subunits forming homo- and hetero-multimers. In order to ensure complete propeptide processing, a r-vWF-producing CHO cell clone was transfected with the cDNA of the human propeptide processing enzyme Furin. A r-vWF/r-Furin co-expressing cell clone was cultivated at industrial scale in high cell density perfusion fermenters. r-vWF obtained from these cells was fully processed. Analysis of r-vWF by multimer analysis revealed a multimer pattern equal in number of high molecular weight multimer to pd-vWF, but absence of satellite bands. Two-dimensional electrophoretic analysis of both the primary dimer and the complete multimer pattern of r-vWF showed that the recombinant coagulation factor was composed exclusively of intact and mature subunits. Since the triplet structure typical to pd-vWF is known to reflect proteolytic degradation, r-vWF thus exhibits an integrity far superior compared to pd-vWF.

Animals↗
PubMed1991

Structural analysis of two-dimensional arrays of cholera toxin B-subunit.

Two-dimensional arrays of cholera toxin B-subunit (CTB) have been obtained by specific interaction with lipid films, as described by Ludwig et al. (1986). The relationship between two types of array, of either rectangular or hexagonal geometry, was analyzed using crystallographic methods of electron image analysis. Our results showed that the type of array obtained was highly dependent on the negative stain used and that both arrays presented related lattice parameters, indicating that they originated from a common unstained structure. Image analysis of hexagonal arrays at 17 A resolution revealed variable CTB projected structures, ranging from annularly symmetric particles to highly asymmetric particles, very distinct from the pentameric structure resolved from rectangular crystals. The present data suggest that hexagonal arrays result from an imperfect staining of CTB rectangular crystals. The staining distortion is such that the stain layer does not match faithfully the pentameric protein distribution whereas the regular organization of the specimen is maintained.

Cholera Toxin↗
PubMed1992

Secondary structural analysis of two recombinant murine proteins, interleukins 1 alpha and 1 beta: is infrared spectroscopy sufficient to assign structure?

The secondary structure for two murine recombinant proteins, interleukins 1 alpha and 1 beta (rmIL-1 alpha and -1 beta), has been analyzed by Fourier transform infrared (IR) spectroscopy and then compared to results obtained by X-ray diffraction, circular dichroism (CD), and nuclear magnetic resonance (NMR) spectroscopy. The IR results obtained here for rmIL-1 alpha and -1 beta suggested that their secondary structures consisted predominantly of beta-sheets or strands. However, the analysis also revealed a significant absorption band near 1656 cm-1, which is typically assigned to alpha-helical or random structures. When these same murine polypeptides were analyzed by CD, no evidence of alpha-helical structures was observed. Further, published X-ray diffraction and NMR studies characterizing the human forms of IL-1 alpha and -1 beta indicate the absence of alpha-helices and that the human proteins are composed mainly of beta-strands (i.e., greater than 55%), with approximately 24% of the amino acids involved in large loops connecting the strands. The murine IL-1 proteins, when compared to their respective human counterparts, each show greater than 80% sequence homology. Given this fact, the CD analyses, and the result that this IR band amounted to 21% of the overall integrated area, the absorption peak at 1656 cm-1 was attributed to the presence of large loops rather than to alpha-helical or random structures. Such a structural assignment appears reasonable and is totally consistent with the established existence of large loops in the human forms as well as in other proteins found to fold similarly (viz., human bFGF).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Improved reproducibility of computer-assisted structural analysis of the optic papilla].

Longitudinal monitoring of the optic disc structure by means of automated nervehead analysis (Optic Nerve Head Analyzer, ONHA) can facilitate the diagnosis of ongoing glaucoma. Until recently, however, longitudinal disc monitoring was complicated by considerable fluctuations of the results measured with the Optic Nerve Head Analyzer. Since March/1990 there is a new software version of the equipment (ONHA-plus). The determination of disc parameters using ONHA-plus proved to be significantly more reliable than the determination using the former ONHA: the mean fluctuation of the neuroretinal rim area measured on 18 normal eyes was 0.07 mm2 (ONHA-plus) compared to 0.094 mm2 (ONHA); the variation coefficient dropped from 7.9% (ONHA) to 4.6% (ONHA-plus). A further improvement of the reproducibility can be obtained by double examinations, because the mean examination time using ONHA-plus is about half as long as the examination time using ONHA. Moreover, ONHA-plus enables the recognition and elimination of unreliable results caused by poor image quality. Due to this increased reliability the ONHA-plus system is a considerably improved equipment for the clinical monitoring of glaucoma patients.

Glaucoma↗
PubMed1983

Structural analysis of diagnostic disagreements.

When different psychiatrists examine a patient, disagreements often occur. Data that can be used to clarify the factors responsible for disagreements are collected routinely but not systematically analyzed. This paper discusses two quantitative methods, cluster analysis and multidimensional scaling, for describing structural properties of disagreement data and for determining from them steps that can be taken to upgrade inter-rater reliability.

Attitude of Health Personnel↗
PubMed1989

Protein and carbohydrate structural analysis of a recombinant soluble CD4 receptor by mass spectrometry.

The primary structure of a soluble form of the CD4 receptor (sCD4) expressed in Chinese hamster ovary cells has been confirmed by mass spectrometric peptide mapping and and tandem mass spectrometry. These studies corroborated 95% of the 369-amino acid-long sequence and established the fidelity of translation of the NH2 and COOH terminal including the absence of "ragged ends." The arrangement of the three disulfide bonds in recombinant sCD4 was also established by mass spectrometry and comparative high performance liquid chromatography mapping and shown to be identical to that expected from previous studies of intrachain disulfide bonding in T4 antigens derived from sheep and mouse. No other arrangements of disulfides were detected. Carbohydrate mapping by mass spectrometry was used to establish that both potential Asn-linked glycosylation sites in sCD4 (Asn271 and Asn300) have oligosaccharides attached. Structural characterization by mass spectrometry and methylation analysis of the heterogeneous family of oligosaccharides at each of the specific attachment sites indicates that the major components of both families of oligosaccharides have the following biantennary structures: (Formula, see text) where m + n = 0-2, and x = 0,1. Minor carbohydrate components having three N-acetylneuraminic acid (NeuAc) groups and an additional hexose-hexosamine unit were detected by high performance anion-exchange chromatography.

Amino Acid Sequence↗
PubMed1992

Structural analysis of lipooligosaccharide produced by Neisseria gonorrhoeae, strain MS11mk (variant A): a precursor for a gonococcal lipooligosaccharide associated with virulence.

We studied the structure of the lipooligosaccharide (LOS) that is produced by a variant A of strain MS11mk. This variant produces a single LOS that is recognized by monoclonal antibody (MAb) 2-1-L8. In a recent study of the pathogenesis of Neisseria gonorrhoeae in male volunteers, variant A gave rise to other phase variants that produce higher molecular weight LOSs, and these LOS were associated with virulence. Definition of the structure of the variant A LOS is important to understand the biosynthesis of LOS and its expression in vivo. The dephosphorylated oligosaccharide (OS) structure derived from the variant A LOS was analyzed by two-dimensional NMR and methylation analysis. The OS structure was found to be a truncated form of the LOS produced by strain F62 [Yamasaki et al. (1991) Biochemistry 30, 10566-10575]; the variant A OS is a hexamer, a beta-lactosyl residue linked to a tetrasaccharide: Gal beta 1-->4Glc beta 1-->4[GlcNAc alpha 1-->2Hep alpha 1-->3]Hep alpha 1-->KDO. We determined that the variant A LOS is a precursor for the synthesis of higher MW LOS. We also studied expression of the MAb 2-1-L8-defined epitope present on the variant A LOS. Our data indicate that the MAb-defined epitope is not a linear beta-lactosyl residue but its specificity is directed toward the phosphorylated GlcNAc-Hep-Hep residue. Since this MAb binds to gonococci, at least part of the phosphorylated diheptose area is exposed on the gonococcal surface.

Antibodies, Monoclonal↗
PubMed1987

Structural analysis of purified beta-adrenergic receptors.

We have characterized the structure of purified beta-adrenergic receptors by a combination of photoaffinity labeling, high performance liquid chromatography (HPLC)-tryptic mapping, CNBr fragmentation, target size analysis, and electron microscopy of purified receptor molecules. Guinea pig lung beta-adrenergic receptors purified by affinity chromatography, ion exchange chromatography, and HPLC size exclusion chromatography or photoaffinity labeled with [125]-iodocyanopindolol diazirine displayed mobilities on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) that corresponded to Mr = 68,000. Purified, radioiodinated guinea pig lung beta-receptors were subjected to complete trypsin digestion and subsequent reverse-phase HPLC analysis, which revealed nine peptides. Active site labeling and tryptic digestion of partially purified hamster lung beta-receptors produced one peptide, whereas CNBr digestion of the same material produced two labeled fragments, yielding information about the location of the active site within the primary sequence. Purified guinea pig lung receptors were examined with transmission electron microscopy. Electron micrographs revealed slightly asymmetric, rod-shaped structures with an average length of 13 nm and width of 3.4 nm. Many receptors were arranged as apparent dimeric structures. These findings confirm data obtained from target size analysis of guinea pig lung beta-receptors in situ which suggest that receptors may exist as oligomeric arrays in the native membrane. Taken together, these data provide information about putative functional domains of the beta-adrenergic receptor and its quaternary structure.

Amino Acid Sequence↗
PubMed1991

Rat urate oxidase: cloning and structural analysis of the gene and 5'-flanking region.

The structural gene (UOX) encoding rat urate oxidase (UOX) spans at least 23 kb and is composed of eight exons and seven introns. All of the exon-intron splice junction sequences conformed to the GT/AG consensus established for eukaryotic genes. The transcription start point (tsp) was determined using S1-type nuclease protection riboprobe, and assigned to an adenine 54 nucleotides (nt) upstream of the ATG start codon. A 456-bp 5'-terminal fragment, starting at the ATG codon, carries a putative TATA (ATAAAA) sequence at -32, and two putative 'CAAT box' sequences at -62 and -71 bp upstream from the tsp. No sequence resembling 'GC' box hexanucleotides (GGGCGG or CCGCCC) was found. The structural features of the 5'-flanking region of the UOX gene are distinct from the 5'-flanking sequences of peroxisomal beta-oxidation system genes which contain one or more 'GC' box elements but lack TATA- and CAAT-like features [Osumi et al., J. Biol. Chem. 262 (1987) 8138-8143; Ishii et al., J. Biol. Chem. 262 (1987) 8144-8150]. The 5'-flanking region of the UOX gene reveals a sequence, TTAGTAATT at nt -276 from the tsp, which appears to be complementary to the underlined part of the liver-specific LF-B1/HNF-1 consensus sequence, GTTAATNATTAAC (where N = A, C, T, G or no nt).

Amino Acid Sequence↗
PubMed1991

Structural analysis of cataract incision construction.

This report examines the structural components of incision construction for cataract surgery so the causes of corneal instability and astigmatism can be understood. Changing the shape of the external incision, from limbus-parallel to linear to curved away from the limbus, results in a more stable external incision. The internal entry incision is more directly associated with corneal instability, however, and its construction and closure are crucial. Corneal stability improves as the closure changes from radial to horizontal to corneal valve autoclosure. Hyphema rates also improve with this progression because blood is directed into the anterior chamber with posterior incision closure, but out of the eye with anterior corneal valve closure.

Astigmatism↗
PubMed1992

Structural analysis of ternary complexes of vaccinia RNA polymerase.

The structure of the elongation complex of vaccinia RNA polymerase halted at discrete template positions was examined by DNase I footprinting. The leading edge of the footprint bore a constant relationship to the catalytic template position, being 22-24 nucleotides (nt) in advance on the nontemplate strand and 17 nt on the template strand. DNase hypersensitivity of the nontemplate strand at the leading edge suggested that the DNA might be distorted as it entered the polymerase molecule. The region of DNA unwinding at the transcription bubble extended at least 12 nt 5' from the catalytic center, as indicated by the reactivity of adenosine residues to diethylpyrocarbonate. Cu-phenanthroline-hypersensitive sites located 13 nt 5' and 4 nt 3' of the growing point appeared to demarcate the margins of the bubble. Strand asymmetry of chemical modification within the bubble was consistent with an RNA-DNA hybrid of no more than 10 base pairs.

Base Sequence↗