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S Knight

Publications and source records attributed to S Knight.

At least 37 records · Page 2Linked to original sources
PubMed1990

Comparison of the crystal structures of L2 and L8S8 Rubisco suggests a functional role for the small subunit.

Comparison of the crystal structures of the L2 and L8S8 forms of ribulose-1,5-bisphosphate carboxylase from Rhodospirillum rubrum and spinach respectively, reveals a remarkable similarity in the overall architecture of the L2 building blocks in the two enzymes. Within the L subunits, no large conformational differences such as domain-domain rotations were found. In spite of a somewhat different packing of the L subunits in the L2 dimer, the active sites of the two enzymes are highly conserved. Significant local conformational differences are, however, observed for the C-terminal part of the polypeptide chains as well as for loop 7, helix alpha 7, loop 8 and helix alpha 8 in the barrel domain. The small subunit forms extensive interactions with one of these alpha helices, alpha 8, in the spinach L8S8 enzyme. The loops are at the active site and one of them forms a phosphate binding site for the substrate. We suggest that the small subunit modulates substrate binding and, possibly, the carboxylation/oxygenation ratio by inducing conformational changes in the active site through interactions distant from this site.

Amino Acid Sequence↗
PubMed1990

Retrophrenic location of the internal mammary artery graft.

A technique of locating the internal mammary artery behind the phrenic nerve is described, which extends the application of internal mammary artery grafting to the lateral wall of the left ventricle. The technique also facilitates the performance of the posterolateral anastomosis between the internal mammary and circumflex coronary arteries.

Humans↗
PubMed1990

Residues in three conserved regions of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase are required for quaternary structure.

To explore the role of individual residues in the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39), small subunits with single amino acid substitutions in three regions of relative sequence conservation were produced by directed mutagenesis of the rbcS gene from Anabaena 7120. These altered small subunits were cosynthesized with large subunits (from an expressed Anabaena rbcL gene) in Escherichia coli. Mutants were analyzed for effects on quaternary structure and catalytic activity. Changing Glu-13S (numbering used is that of the spinach enzyme) to Val, Trp-67S to Arg, Pro-73S to His, or Tyr-98S to Asn prevented accumulation of stable holoenzyme. Interpretation of these results using a model for the three-dimensional structure of the spinach enzyme based on x-ray crystallographic data suggests that our small subunit mutants containing substitutions at positions 13S and 67S probably do not assemble because of mispairing or nonpairing of charged residues on the interfacing surfaces of the large and small subunits. The failure of small subunits substituted at positions 73S or 98S to assemble correctly may result from disruption of intersubunit or intrasubunit hydrophobic pockets, respectively.

Amino Acid Sequence↗
PubMed1990

Analysis of very late gene expression by Autographa californica nuclear polyhedrosis virus and the further development of multiple expression vectors.

The consequences of locating the polyhedrin gene coding sequences and the p10 promoter at heterologous positions within the Autographa californica nuclear polyhedrosis virus (AcMNPV) genome were investigated. Positioning the polyhedrin or beta-galactosidase coding sequences under the control of the p10 gene promoter via the use of the new transfer vector, pAcUW1, resulted in viable recombinant viruses able to produce high levels of each non-fused gene product at the appropriate time. Polyhedra were also produced by the virus with the p10 promoter-polyhedrin hybrid gene and appeared normal in thin sections. Therefore the combination of polyhedrin promoter and coding sequences is evidently not essential for efficient expression of this protein. The p10 promoter can serve this function equally well. Viruses with the p10 promoter and beta-galactosidase coding sequences placed upstream from the polyhedrin gene in either orientation produced large amounts of beta-galactosidase protein in infected cells, thus demonstrating that the p10 promoter can function at an alternative position within the virus genome. A second transfer vector, pAcUW2B, was constructed, with a copy of the p10 gene promoter placed upstream and in opposition to the polyhedrin gene. This mediates the insertion of any foreign gene under the control of the p10 promoter while preserving normal p10 gene expression. The advantages of these constructs over the conventional vectors presently used to express foreign genes in insect cell systems and their utilization in the production of virus insecticides are discussed.

Animals↗
PubMed1990

Muramic acid is not detectable in Chlamydia psittaci or Chlamydia trachomatis by gas chromatography-mass spectrometry.

By using the powerful separation technique of capillary gas chromatography combined with the selectivity of mass spectrometric detection, muramic acid was not detectable in purified elementary bodies of Chlamydia psittaci Cal 10 (less than or equal to 0.006%) or C. trachomatis serovar E (less than or equal to 0.02%). This confirms previous reports which suggested the absence of a typical peptidoglycan in Chlamydia spp.

Chlamydia trachomatis↗
PubMed1989

Isolation of a gene that down-regulates nitrate assimilation and influences another regulatory gene in the same system.

Glutamine is the preferred source of nitrogen of Neurospora crassa. In its presence and that of the gene product of MS5 (nmr-1), the fungus represses the assimilation of less preferred forms of nitrogen, such as nitrate. In the absence of glutamine and the presence of the product of gene nit-2, less preferred forms of nitrogen are assimilated as long as a specific pathway for their assimilation is induced. We report here the isolation, from a cosmid bank, of a gene that complements MS5 and can also complement nit-2. We speculate that this result suggests an interaction between the MS5 and nit-2 gene products and that this is important in the regulation of nitrate assimilation.

Cosmids↗
PubMed1987

Silent partners: the wives of sleep apneic patients.

The wives of 10 male patients being treated for sleep apnea, obstructive type, were interviewed and given the Social Adjustment Scale (SAS) and Marital Satisfaction Inventory (MSI). The patients also completed an SAS and a Minnesota Multiphasic Personality Inventory (MMPI). These data were compared with those from a sample of divorced patients from the same pool. The married patients were significantly more depressed and socially isolated than were those divorced. Both marital partners showed poor adjustment in the Marital and Social/Leisure areas, and patients also showed poor adjustment in their Parental Role. Marriages do not necessarily represent social support but appear to be an added burden for sleep apneic patients.

Adult↗
PubMed1985

Active site specific cadmium(II)-substituted horse liver alcohol dehydrogenase: crystal structures of the free enzyme, its binary complex with NADH, and the ternary complex with NADH and bound p-bromobenzyl alcohol.

Three crystal structures have been determined of active site specific substituted Cd(II) horse liver alcohol dehydrogenase and its complexes. Intensities were collected for the free, orthorhombic enzyme to 2.4-A resolution and for a triclinic binary complex with NADH to 2.7-A resolution. A ternary complex was crystallized from an equilibrium mixture of NAD+ and p-bromobenzyl alcohol. The microspectrophotometric analysis of these single crystals showed the protein-bound coenzyme to be largely NADH, which proves the complex to consist of CdII-LADH, NADH, and p-bromobenzyl alcohol. Intensity data for this abortive ternary complex were collected to 2.9-A resolution. The coordination geometry in the free Cd(II)-substituted enzyme is highly similar to that of the native enzyme. Cd(II) is bound to Cys-46, Cys-174, His-67, and a water molecule in a distorted tetrahedral geometry. Binding of coenzymes induces a conformational change similar to that in the native enzyme. The interactions between the coenzyme and the protein in the binary and ternary complexes are highly similar to those in the native ternary complexes. The substrate binds directly to the cadmium ion in a distorted tetrahedral geometry. No large, significant structural changes compared to the native ternary complex with coenzyme and p-bromobenzyl alcohol were found. The implications of these results for the use of active site specific Cd(II)-substituted horse liver alcohol dehydrogenase as a model system for the native enzyme are discussed.

Alcohol Dehydrogenase↗
PubMed1985

The influence of D.D.A.V.P. on the survival of factor VIII in severe haemophiliacs.

The effect of D.D.A.V.P. (desamino-cys'-D-arg8-Vaso-pressin) on the survival characteristics of transfused VIII concentrate was studied in six severe, adolescent, haemophiliacs (VIII:C 1 iu/dl). D.D.A.V.P. was administered at a concentration of 0.3 ug/kg immediately following or 24 hours post infusion. No significant alteration in the half disappearance (1/2 d) or biological half-life (t 1/2) was detected for either VIII procoagulant (VIII:C) or its antigenic counterpart VIII:C Ag. As anticipated there was a significant (if sub-optimal) increase in VIII:R Ag within 2-4 hours of D.D.A.V.P. administration.

Blood Transfusion↗
PubMed1985

Partial trisomy 11p with interatrial septal aneurysm. Case report and literature review.

A newborn female infant presented with hypotonia, joint hyperextensibility, cardiac murmur, macroglossia, and hepatosplenomegaly. Karyotype of the child revealed partial trisomy of chromosome 11p derived from a paternal balanced translocation. Echocardiogram obtained in the newborn period suggested interatrial aneurysm, which was confirmed on post-mortem examination. Interatrial septal aneurysm is a rare abnormality not previously described in partial trisomy 11p.

Chromosome Banding↗
PubMed1984

Broken dreams: a study of the effects of divorce and depression on dream content.

To investigate the dream characteristics associated with a major life change, 29 women (ages 30-55) undergoing divorce were studied six nights in a sleep laboratory. The group was stratified on a self-report depression scale (the Beck Depression Inventory) into a depressed (N = 19, mean = 23.2) and nondepressed (N = 10, mean = 8.2) group and compared to a nondepressed married group who had never considered divorce. The dreams of those divorcing without major mood upset were longer and dealt with a wider time frame than those of the other two groups. They also dealt with marital status issues which were absent in the dreams of the depressed group. On follow-up those who had been depressed showed positive dream changes in mood, dreamlike quality, and identification of dream self with the marital role. The study suggests that some dream characteristics respond adaptively during life changes but that this is delayed when subjects are depressed. This raises the possibility of a corrective intervention for such persons.

Adult↗