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  • Biochemistry and Biotechnology  (15)
  • 1
    ISSN: 0887-3585
    Keywords: membrane proteins ; channels ; circular dichroism spectroscopy ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The secondary structure of alamethicin, a membrane channel-forming polypeptide, has been examined by circular dichroism spectroscopy to determine the relationship of its conformation in organic solution to its conformation in a membrane-bound state. The spectrum of alamethicin in small unilamellar dimyristoyl phosphatidylcholine vesicles is significantly different from its spectrum in 10% methanol/acetonitrile, the solvent from which it was crystallized (Fox and Richards: Nature 300:325-330, 1982), as well as its spectrum in methanol, the solvent in which NMR studies have been done (Banerjee and Chan: Biochemistry 22:3709-3713, 1983). This suggests that structural models based on studies of the molecule in organic solvents may not be entirely appropriate for the membrane-bound state. To distinguish between different models for channel formation and insertion, two different methods were used to associate the alamethicin with vesicles; in addition, the effect of oligomerization on the conformation of the membrane-bound state was investigated. These studies are consistent with a modified insertion model in which alamethicin monomers, dimers, or trimers associate with the bilayer and then spontaneously oligomerize to form a prechannel with a higher helix content. This aggregate could then “open” upon application of an appropriate gating transmembrane potential.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 1075-2617
    Keywords: Litoria genimaculata ; skin glands ; glandular secretions ; peptides ; antibiotic activity ; maculatins 1 ; caerin 1.1 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Six peptides have been isolated and characterized from the dorsal glands of the tree frog Litoria genimaculata. One of these is the known hypotensive peptide caerulein; the others have been named maculatins. The amino acid sequences of the maculatin peptides have been determined using a combination of fast atom bombardment mass spectrometry and automated Edman sequencing. Four of the maculatin peptides show antibiotic activity, with maculatin 1.1 [GLFGVLAKVAAHVVPAIAEHF(NH2;)] showing the most pronounced activity, particularly against Gram-positive organisms. Maculatin 1.1 resembles the known caerin 1 antibiotic peptides, except that four of the central amino acid residues (of the caerin 1 system) are missing in maculatin 1.1. A comparison of the antibiotic activity of maculatin 1.1 with those of caerin 1.1 is reported. ©1998 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 12 (1970), S. 321-331 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Through the use of pilot plant equipment, transaldolase types I, II, and III (from Candida utilis) have been separated and purified. The procedure includes a time sensitive solvent fractionation below 0°C, ion exchange chromatography, and crystalization. The enzyme yield represents a 41% recovery of crystalline type III and partially purified types I and II.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have demonstrated that a simple electrochemical cell can serve as a detector of NADH concentration in a flow system thereby providing an assay technique for NADH dependent enzymes. When this is applied to NADH produced by enzymatic reaction, then a reproducible measure of enzyme activity is obtained. This method of enzyme activity assay is applicable to a number of oxidoreductase enzymes which employ NAD+ or NADP+ as coenzymes to achieve substrate modification. The presence of electroactive species in samples of human serum has proved a serious problem in the electrochemical analysis of serum activity. These species produce a large background anode current at the anode voltage appropriate for NADH oxidation. The presence of this high current limits the usefulness of amplification of the current output to detect small changes in NADH concentration.
    Additional Material: 13 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 403-420 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Graphites of different manufacture and origin exert positive but different accelerations on the rate of oxidation of NADH to NAD+ in aqueous solution; different proportions of the oxidized form of NAD retain enzymatic activity depending on the nature of the graphite. Oxidative pretreatment of the graphite surfaces increases the rates of NADH oxidation, but subsequent silanization of the surfaces to attach alkylamine groups causes the rates to decrease. The experimental results suggest the presence of at least two types of sites on graphite surfaces: One very reactive site which produces a high percentage of an enzymatically inactive reaction product of NADH and is itself deactivated during the course of reaction, and another type of site which promotes the oxidation of NADH to enzymatically active NAD+ in high yields.
    Additional Material: 5 Ill.
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  • 6
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aspen (Populus tremuloides) and black cottonwood (Populus trichocarpa) organosolv pulps produced in a wide range of solvent composition (between 30 and 70% by volume of methanol) and catalysts (H2SO4 and H3PO4) such that the cooking liquor pH ≤ 3 are easily digested by enzymes. The total yields of hydrolysis residues (pulps) are in the 40-60% range; the acid-catalyzed delignification followed by enzyme hydrolysis can generate 70-88% of the original six-carbon sugars contained in the wood. Glucomannan and arablnogalactan are dissolved into the pulping liquor in the pH range of 2-4.5. Lower pH (≤3) leads to additional solubilization of six-carbon sugars. These sugars may be fermented directly. From the insoluble hydrolysis residues, 36-41% conversions of wood into fermentable sugars were obtained after enzyme hydrolysis; the starting feedstocks contain 50.8 and 46.6% hexosans, respectively, for aspen and black cotton-wood. The kinetics of enzymatic hydrolysis of cellulose can be formally treated as two simultaneous pseudo-first-order reactions in which fast and slow hydrolyses of cellulose occur. Correlations between the glucan digestibility and the effect of the pretreatment have been made. The higher residual xylan content reduces the amount of the rapidly hydrolyzable glucan fraction and lowers the glucan digestibility. The proposed simple kinetic treatment is very helpful in assessing the effect of the pretreatment on pulp enzyme hydrolyzability.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 1075-2617
    Keywords: Litoria xanthomera ; skin glands ; glandular secretion ; antibacterial peptides ; caerins 1 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The secretion of the skin glands of the ‘orange-thighed frog’ Litoria xanthomera contains seven peptides. One of these is the known hypotensive peptide caerulein. Two new peptides, caerin 1.6 [GLFSVLGAVAKHVLPHVVPVIAEKL(NH2)], and caerin 1.7 [GLFKVLGSVAKHLLPHVAPVIAEKL(NH2)] show antibacterial properties. Two other peptides lack the first two amino acid residues of caerins 1.6 and 1.7 and show no antibacterial activity. The identification of the peptides in Litoria xanthomera confirms that this species is related to Litoria caerula, Litoria gilleni and Litoria splendida but not as closely as those three species are related to each other. © 1997 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 266-270 
    ISSN: 0173-0835
    Keywords: Oral microorganisms ; Parotid saliva ; Proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Bacterial colonisation of oral surfaces by microorganisms may be dependent on their interaction with specific host receptor molecules. Primary oral colonisers are known to remove specific proteins from parotid saliva. The aim of this study was to determine whether these interactions facilitate microbial attachment to a surface and hence identify specific salivary components as putative host receptor molecules. Parotid saliva was resolved by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and then electroblotted onto nitrocellulose membranes. Suspensions of fluorescently labelled microoganisms were incubated with the blots and salivary components with adherent bacteria identified as fluorescent bands under ultraviolet (UV) transillumination. Species of streptococci known to be early colonisers of the clean tooth surface were found to adhere specifically to certain salivary proteins, especially to basic proline-rich proteins (PRPs). Polymorphic variations in these patterns could form the basis of differences in oral microflora, susceptibility to oral infections and consequent disease.
    Additional Material: 3 Ill.
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  • 9
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Ligase chain reaction products ; Mitochondrial DNA ; Point mutations ; Leber's hereditary optic neuropathy ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: High speed capillary electrophoresis-laser-induced fluorescence (CE-LIF) has been used to separate and detect point mutations using the ligase chain reaction (LCR). The method utilizes short capillary columns (7.5 cm effective length) and fields of 400 V/cm to analyze DNA-ethidium bromide complexes using an He/Ne laser. The method was first demonstrated with a commercially available kit for LCR based on a lacI gene fragment inserted in a Blusescript® II phagemid. LCR-CE-LIF was then applied to detect point mutations in human mitochondrial DNA. resulting in Leber's hereditary optic neuropathy (LHON). Three severe mutations were analyzed in which the original base is substituted by a thymidine base at positions 3460, 11778 and 14459. Appropriate primers were designed with polyT tails for length discrimination of pooled samples. Successful detection of mutated samples was achieved, with appropriate correction for small amounts of nonspecific ligated product. The method is rapid, easy to implement, and automatale.
    Additional Material: 8 Ill.
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  • 10
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The effects of concentration on immunoglobulin G (IgG) oligoclonal bands after isoelectric focusing in cerebrospinal fluids (CSF) were examined using six concentration procedures, and the percent recoveries of IgG varied. The procedures, % IgG recoveries, and corresponding degrees of concentration are as follows: (1) Amicon CF25 membrane cone, 75 %, 45 ×; (2) Amicon CF50A membrane cone, 65 %, 3 ×; (3) Amicon CS15 Minicon, 47 %, 80 ×; (4) Microprodicon, 55 %, 35 ×; (5) collodion bag negative pressure dialysis, 50 %, 16 ×; and (6) microcollodion bag in Permasorb, 40-80 %, 10-60 ×. Ultracentrifugation of CSF at 100 000 g for 1 h prior to concentration using CF 25 membrane cones introduced not more than 5 % variation in the IgG concentrations. Isoelectric focusing was performed on 20 CSF samples concentrated by CF25 membrane cone, CS15 Minicon, and collodion bag, and no effects on the oligoclonal IgG banding patterns were found.
    Additional Material: 4 Ill.
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