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141.
A molecular model for the complex formed between the jack bean lectin concanavalin A (Con A) and glycopeptides of the complex biantennary class is described. The model was derived using coordinates for Con A determined by x-ray crystalographic refinement techniques, with 1.75-Å resolution data, and coordinates for the glycopeptides obtained from 1H-nmr measurements, using the nuclear Overhauser effect. Previous solution and crystallographic studies provided several constraints on the possible mode of interaction of the lectin and the glycopeptide. Examination of the model suggests that the glycopeptide binding site is defined by four loops on the protein surface made up by amino acid residues: 12–18, 98–102, 205–208, and 226–229. Within these loops, it favorable interactions with high-affinity ligands and tose responsible for the unfavourable interactions with poor ligands. 相似文献
142.
143.
Bovine mammary epithelial cells cultured on floating gels of rat tail collagen showed two principal cell types, columnar and squamous, with ultrastructural features resembling secretory and myoepithelial cells respectively. Cultures of freshly prepared cells released alpha-lactalbumin into the culture medium and in some cases contained fat droplets, although these did not appear to be released. No ultrastructural evidence of casein synthesis was observed. A notable feature was the failure to secrete a continuous basement membrane. Intermediate filaments were present in abundance in squamous epithelial cells. 相似文献
144.
Walker D. C.; MacKenzie A. L.; Wiggs B. R.; Montaner J. G.; Hogg J. C. 《Journal of applied physiology》1988,64(6):2348-2356
This study is intended to determine whether qualitative assessment of tight junction integrity from freeze-fracture data is reliable. We used lung parenchyma from a control mongrel dog's cardiac lung lobe, from a mongrel dog subjected to vascular high-pressure pulmonary edema (HPPE), and from a dog subjected to oleic acid-induced low-pressure pulmonary edema (LPPE) (6). Quantitative assessment was done on 115 freeze-fracture micrographs of epithelial tight junctions and on another 158 freeze-fracture micrographs of endothelial junctions from the 3 dogs. Quantitative assessment showed differences between the dogs in junction depth, fibril numbers, density, and complexity. for qualitative assessment, these same 273 micrographs were assessed in a single-blind fashion by having six investigators sort first the epithelial and then the endothelial junctions into normal or damaged categories. Qualitative assessment did not agree with quantitative data, suggesting that it is unreliable. 相似文献
145.
146.
Soil Zn extracted by 0.25M MgCl2 or DTPA as an index of Zn availability was compared to Zn or P:Zn concentration in leaves for 40 commercial apple orchards
in southern British Columbia. Sampled trees included a wide range of ages and cultivar/rootstock combinations. Leaves were
sampled from the midportion of current season's shoots at four times; May–June 1984, July 1984, May 1985 and July 1985. At
the same time the severity of the four Zn deficiency symptoms, rosetting, blind bud, little leaf and chlorosis was assessed.
Little relationship was found between soil and leaf Zn measures, except in July 1984, when both terminal leaf Zn and P:Zn
concentrations varied directly with 0.25M MgCl2 extractable soil Zn. Soil Zn extracted by 0.25M MgCl2 was more closely related to severity of deficiency symptoms on the trees at all four samples dates than was DTPA-soil Zn
or leaf Zn concentration. Blindbud was the most useful indicator of deficiency in samples collected in May whereas chlorosis
was the most useful one in July. 相似文献
147.
Ian N. Roberts Donald A. MacKenzie David J. Jeenes David B. Archer Sheena E. Radford Carol V. Robinson Robin T. Aplin Christopher M. Dobson 《Biotechnology letters》1992,14(10):897-902
Summary
Aspergillus niger has been used as a host organism for the production of15N-labelled hen egg white lysozyme (HEWL). In order to achieve maximum incorporation of label, strains expressing the HEWL gene were grown in medium containing ammonium15N chloride as sole nitrogen source. Yields of HEWL protein were reduced relative to those obtained on more complex media. Gains in yield using complex media were offset by reduction in15N incorporation. No differences in either yield or kinetics of production were observed when ammonium15N chloride was replaced by unlabelled ammonium chloride as sole nitrogen source. Yields of15N-HEWL produced in this way are adequate for, and offer considerable advantages to, NMR studies of structure and folding of mutant and wild-type lysozymes. 相似文献
148.
C Tsilfidis A E MacKenzie G Shutler S Leblond J Bailly K Johnson R Williamson J Siegel-Bartelt R G Korneluk P Shelbourne 《American journal of human genetics》1991,49(5):961-965
Recent genetic linkage studies have mapped the myotonic dystrophy (DM) locus to 19q13.3. All closely linked DM markers identified to date have been located on the centromeric side of the disease locus, with a relatively large genetic interval (9 cM) observed between the nearest distal marker and DM. We show here that the recently described marker p134C is tightly linked to DM (peak lod score 35.8 at peak recombination fraction .006) and confirm the previous suggestion that the p134C locus, D19S51 maps distal to the disease locus. D19S51 and the closest proximal flanking loci, ERCC1 and D19S115 (pE0.8), define a small genetic interval of less than 2 cM that contains the DM locus. 相似文献
149.
applications of electroporation of adherent cellsIn Situ,on a partly conductive slide 总被引:5,自引:0,他引:5
Raptis Leda H. Brownell Heather L. Liu Stanley K. W. Firth Kevin L. MacKenzie Leslie W. Stiles Charles D. Alberta John A. 《Molecular biotechnology》1995,3(2):129-134
One of the most important factors affecting the quality of PCR is the choice of primers. In general, the longer the PCR product
the more difficult it is to select efficient primers and set appropriate designing primers, and in general, the more DNA sequence
information is available, the better the ch0ance of finding an optimal primer pair. Efficient primers can be designed by avoiding
the following flaws: primer-dimer formation, self-complementarity, too lowT
m
of the primers, and/or their incorrect internal stability profile. Tips on subcloning PCR products, calculating duplex stability
(predicting dimer formation strength), and designing degenerate primers are given. 相似文献
150.
D. B. Archer D. A. MacKenzie M. J. Ridout 《Applied microbiology and biotechnology》1995,44(1-2):157-160
The secreted production of a heterologous enzyme, hen egg-white lysozyme, by Aspergillus niger was studied in shake flasks containing media of different initial viscosities. Raising the viscosity of the medium by addition of polyvinylpyrrolidone (PVP) brought about a transition in the form of growth from aggregated mycelia (pellets) to dispersed mycelia. The specific yield of lysozyme in cultures containing an initial concentration of 5% (w/v) starch was 8 mg lysozyme/g dry weight. Addition of 2% (w/v) PVP to the medium resulted in a specific yield of 14 mg lysozyme/g dry weight. 相似文献