Search PubMed⌕ Search

Biomedical subjects

J E Harthill

Publications and source records attributed to J E Harthill.

At least 19 recordsLinked to original sources
PubMed2002

Affinity purification of diverse plant and human 14-3-3-binding partners.

Many proteins that bind to a 14-3-3 column in competition with a 14-3-3-binding phosphopeptide have been purified from plant and mammalian cells and tissues. New 14-3-3 targets include enzymes of biosynthetic metabolism, vesicle trafficking, cell signalling and chromatin function. These findings indicate central regulatory roles for 14-3-3s in partitioning carbon among the pathways of sugar, amino acid, nucleotide and protein biosynthesis in plants. Our results also suggest that the current perception that 14-3-3s bind predominantly to signalling proteins in mammalian cells is incorrect, and has probably arisen because of the intensity of research on mammalian signalling and for technical reasons.

14-3-3 Proteins↗
PubMed1998

Core alpha1,3-fucose is a key part of the epitope recognized by antibodies reacting against plant N-linked oligosaccharides and is present in a wide variety of plant extracts.

Carbohydrates have been suggested to account for some IgE cross-reactions between various plant, insect, and mollusk extracts, while some IgG antibodies have been successfully raised against plant glycoproteins. A rat monoclonal antibody raised against elderberry abscission tissue (YZ1/2.23) and rabbit polyclonal antiserum against horseradish peroxidase were screened for reactivity in enzyme-linked immunosorbent assay against a range of plant glycoproteins and extracts as well as neoglycoproteins, bee venom phospholipase, and several animal glycoproteins. Of the oligosaccharides tested, Man3XylFucGlcNAc2(MMXF3) derived from horseradish peroxidase was the most potent inhibitor of the reactivity of both YZ1/2.23 and anti-horseradish peroxidase to native horseradish peroxidase glycoprotein. The reactivity of YZ1/2. 23 and anti-horseradish peroxidase against Sophora japonica lectin was most inhibited by a neoglycoconjugate of bromelain glycopeptide cross-linked to bovine serum albumin, while the defucosylated form of this conjugate was inactive as an inhibitor. A wide range of plant extracts was found to react against YZ1/2.23 and anti-horseradish peroxidase, with particularly high reactivities recorded for grass pollen and nut extracts. All these reactivities were inhibitable with the bromelain glycopeptide/bovine serum albumin conjugate. Bee venom phospholipase and whole bee venom reacted weakly with YZ1/2.23 but more strongly with anti-horseradish peroxidase in a manner inhibitable with the bromelain glycopeptide/bovine serum albumin conjugate, while hemocyanin from Helix pomatia reacted poorly with YZ1/2.23 but did react with anti-horseradish peroxidase. It is concluded that the alpha1, 3-fucose residue linked to the chitobiose core of plant glycoproteins is the most important residue in the epitope recognized by the two antibodies studied, but that the polyclonal anti-horseradish peroxidase antiserum also contains antibody populations that recognize the xylose linked to the core mannose of many plant and gastropod N-linked oligosaccharides.

Animals↗
PubMed1992

cDNA, amino acid and carbohydrate sequence of barley seed-specific peroxidase BP 1.

The major peroxidase of barley seed BP 1 was characterized. Previous studies showed a low carbohydrate content, low specific activity and tissue-specific expression, and suggested that this basic peroxidase could be particularly useful in the elucidation of the structure-function relationship and in the study of the biological roles of plant peroxidases (S.K. Rasmussen, K.G. Welinder and J. Hejgaard (1991) Plant Mol Biol 16: 317-327). A cDNA library was prepared from mRNA isolated from seeds 15 days after flowering. Full-length clones were obtained and showed 3' end length variants, a G+C content of 69% in the translated region, a 90% G or C preference in the wobble position of the codons and a typical signal peptide sequence. N-terminal amino acid sequencing and sequence analysis of tryptic peptides verified 98% of the sequence of the mature BP 1 which contains 309 amino acid residues. BP 1 is the first characterized plant peroxidase which is not blocked by pyroglutamate. BP 1 polymorphism was observed. BP 1 is less than 50% identical to other plant peroxidases which, taken together with its developmentally dependent expression in the endosperm 15-20 days after flowering, suggests a unique biological role of this enzyme. The barley peroxidase is processed at the C-terminus and might be targeted to the vacuole. The single site of glycosylation is located near the C-terminus in the N-glycosylation sequon -Asn-Cys-Ser- in which Cys forms part of a disulphide bridge. The major glycan is a typical plant modified-type structure, Man alpha 1-6(Xyl beta 1-2)Man beta 1-4GlcNAc beta 1-4(Fuc alpha 1-3)GlcNAc. The BP 1 gene was RFLP-mapped on barley chromosome 3, and we propose Prx5 as the name for this new peroxidase locus.

Amino Acid Sequence↗
PubMed1984

Structure-activity in the carrageenans: iota-carrageenan and experimental oedemagenic activity.

The oedemagenic activities of several iota-carrageenans from Eucheuma spinosum have been compared using the rat hindpaw model. From the parent iota-carrageenan of weight average molecular weight 541 100 an acid-degraded iota-carrageenan (Mw = 20 300) was obtained which on fractionation yielded five iota-carrageenans Mw ranging from 73 700 to 4 600. The oedemagenic activity of iota-carrageenan resided in the fraction of Mw = 73 700, the parent undegraded high molecular weight iota-carrageenan being no more active and fractions of lower molecular weight being inactive. Fractionation was based on differential solubilities of the barium salts of the fractions in water and aqueous ethanol and was probably determined by aspects of primary structure in addition to molecular weight.

Animals↗
PubMed1982

The anticoagulant activity of heparins in dextrose solutions.

Changes with time in the anti-factor Xa activity of several heparins were determined in freshly autoclaved and unautoclaved dextrose solutions. In the former, activity was raised, in the latter a reversible fall occurred at certain heparin concentrations, and the term "dextrose effect' is applied to the difference in activity in the two types of dextrose solutions. A simple dependence on heparin concentration for the rise in activity in autoclaved dextrose solutions contrasted with a threshold heparin concentration in the unautoclaved dextrose solutions. Above this a fall and below it a rise in activity were demonstrated with one factor Xa method. The pH of the two dextrose solutions differed by one unit but pH was not the principal factor in the effect; salt tended to eliminate the dextrose effect which was found mostly with the high and to some extent also with the low molecular weight fractions of pharmacopoeial heparin. There was no evidence for heparin degradation but activity changes, which differed for different heparins, are thought to be associated with the effects of heparin-dextrose interaction modified in the case of autoclaved dextrose by by-products of autoclaving. Generally, proprietary dextrose solutions gave variable results.

Anticoagulants↗
PubMed1982

The macroanionic activity of heparins in the presence of dextrose and calcium ion.

The effect of dextrose on heparin was investigated using the heparin-azur A interaction as a measure of macroanionic activity. Dextrose solutions did not diminish heparin-azur A metachromasia but prior autoclaving of the dextrose solution resulted in a slight decrease. When calcium chloride was added to the dextrose (autoclaved or unautoclaved) there was a reduction which was greater than that caused by calcium ion in the absence of dextrose. The effects of calcium ion and dextrose acting together were each concentration - dependent. A low molecular weight fraction (8400) was more susceptible to the effects of calcium in the presence of dextrose than a fraction of mol. wt. 19 000, hence unfractionated heparins with different amounts of various fractions may respond differently to calcium in the presence of dextrose. This has not been considered in earlier studies of the anticoagulant activity of unfractionated heparins in dextrose infusion and could has contributed to reported discrepancies, particularly in view of the variety of test methods used. At present, it is not possible to predict from in vitro tests whether dextrose will modify the in vivo anticoagulant activity of heparin.

Anions↗
PubMed1980

The influence of molecular size and pH on the macrocationic inhibition of pepsin by polylysine.

Polylysines of 7-371 lysine residues inhibited pepsin over the pH range 3.6-5.0 in a system using azocoll as substrate. Tetralysine was inactive. An almost 1:1 molar ratio with pepsin gave maximum inhibition for a polylysine containing 59 lysine residues but increase in polylysine molecular size beyond this size was not accompanied by increase in activity on a weight basis although the polylysine:pepsin molar ratio for maximum inhibition decreased and inhibition mechanism varied. Polylysines of 59 and 158 lysine residues which were intermediate in the series were non-competitive inhibitors, whilst polylysines of greater and smaller molecular size were competitive inhibitors, although only the smallest inhibitory polylysine, containing 7 lysine residues, was a pure competitive inhibitor. Polylysine inhibition of pepsin was found to be strongest at pH 5.0 and the pH dependence appeared to be associated with the relative concentrations of the enzyme and inhibitors in ionized form. For each polylysine it was possible to detect a polylysine:pepsin concentration ratio for which inhibition was pH-independent over the range 3.6-5.0.

Binding, Competitive↗
PubMed1980

Barium sulphate preparations for use in double contrast examination of the upper gastrointestinal tract.

Physical properties relevant to upper gastrointestinal radiology have been compared for five barium sulphate preparations and related to radiographic results. Evaluation of particles (size and stability) and whole suspension (dispersibility and fluidity) resulted in ranking of the preparations generally in accord with that based on radiological experience in double contrast examinations of the stomach. Experiments with extirpated pig stomach revealed a tendency for large particles in a low viscosity barium sulphate suspension to settle in mucosal grooves. This is believed to contribute to good radiographic definition of both the areae gastricae and small lesions. Particle size is therefore important and susceptibility to flocculation, a possible cause of random change in size during use, was assessed by measuring particle electrophoretic mobility under varying conditions; quantitative differences in suspension flow and dispersibility were also demonstrated. Fluidity and dispersibility together with rapid sedimentation of suitably sized particles resistant to flocculation underlie the successful use of low viscosity high density barium sulphate suspensions.

Animals↗
PubMed1980

Areae gastricae.

Explore the source record for details and available documents.

Animals↗