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  • Chemistry  (4)
  • Hypertonic sucrose  (1)
  • Wiley-Blackwell  (5)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 189-196 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present paper we describe the synthesis, purification, and single-crystal x-ray analysis of the cyclic tetrapeptide cyclo-(L-Pro-L-Phe-β-Ala-β-Ala). This compound contains the β-alanyl-β-alanine dipeptide as putative cyclization arm to force the remaining dipeptide-L-Pro-L-Phe- in a β-turned conformation. Thepeptide was synthesized by classical methods and cyclization of the free linear tetrapeptide was accomplished in reasonable yields in diluted methylene chloride solution. The compound crystallizes in space group P21 from hot water with two independent tetrapeptide molecules and seven solvent molecules in the unit cell. This compound shows in the solid state an intramolecular hydrogen bond between the CO group of the β-Ala4 and the NH group of the β-Ala3 residues stabilizing a type I β-turn conformation in which Pro1 and Phe2 occupy the relative position 2 and 3 of the turn, respectively. A rather complex network of 18 hydrogen bonds involving all the remaining CO and NH groups and the water molecules is present in the crystal.
    Additional Material: 3 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 31 (1991), S. 1181-1188 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the present paper we describe the synthesis, purification, and single crystal x-ray analysis of the cyclic pentapeptide cyclo-(L-Pro-L-Pro-L-Phe-β-Ala-β-Ala). The peptide was synthesized by classical solution methods and the cyclization of the free pentapeptide was accomplished in good yields in diluted methylenechloride solution using N,N-dicyclohexylcarbodiimide. The compound crystallizes in the monoclinic space group P21 from hot water with five solvent molecules. The Pro1-Pro2 peptide bond is cis and the molecular conformation is stabilized by an intramolecular hydrogen bond between the CO group of the β-Ala5 and the NH of the Phe3 residue. The Pro1-Pro2 segment occupies the relative positions 2 and 3 of a type VIa β-turn, while the L-phenylalanyl-β-alanyl-β-alanine segment is incorporated in a C13-like ring structure. The crystal packing is characterized by a network of 11 intermolecular hydrogen bonds involving all the remaining CO, NH, and the water molecules.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 110-117 
    ISSN: 1040-452X
    Keywords: Rabbit embryos ; Hypertonic sucrose ; Micromanipulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Rabbit zygotes and embryos were exposed to hypertonic sucrose in phosphate-buffered saline (SPBS). In experiment one, 144 zygotes shrank to 32-36% of their initial volume in 1.0 M SPBS within 30 min. Neither hypertonic treatment with 0.5 M or 1.0 M SPBS nor micropuncture of the zona pellucida after shrinkage affected embryo development into blastocysts in vitro (88%, 83%, and 82%, respectively), compared to that of the controls (93%, P 〉 .05). In experiment two, 252 two- to four-cell- and 177 morula-stage embryos were exposed to isotonic PBS control or 0.5 M, 1.0 M, or 1.5 M SPBS for 30, 60, 90, 120, and 150 min before transfer to PBS (290 mOsm). Embryo development was significantly reduced (P 〈 .05) when embryos were exposed in 0.5 M and 1.0 M SPBS for more than 60 min or in 1.5 M SPBS for more than 30 min. In experiment 3, morulae exposed for 60 min to 0.5 M or 1.0 M SPBS shrank to 37-39% or 32-35% of their initial volume and then expanded to 87-94% or 81-90% of their initial volume, respectively, after being returned to isotonic PBS for 60 min, but embryos in 1.5 M SPBS had erratic osmotic behavior. In experiment four, 192 two- to four-cell embryos exposed to 0.5 M SPBS for 0, 30, and 60 min before transfer to oviducts of recipients resulted in the production of 39%, 42% and 31% young, respectively (P 〉 .05). Exposure of embryos to 0.5 M sucrose for 60 min clearly does not compromise developmental potential and can simplify and speed up micromanipulation procedures.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1479-1486 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this paper, the blends of the carbon dioxide copolymer, poly(propylene carbonate) (PPC), with nitrile rubber (NBR) were studied by DSC, DMA, TEM and TG. PPC can enhance the mechanical properties of NBR, while oil resistance and tensile set at break of NBR/PPC systems were as good as that of NBR. The coagent of triallylisocyanurate or maleic anhydride with carbon black can much improve the curing efficiency of dicumyl peroxide in NBR/PPC systems. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 105-108 
    ISSN: 1040-0397
    Keywords: Putrescine ; Polyamine ; Enzyme electrode ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A putrescine biosensor has been developed. Putrescine oxidase, peroxidase, and bovine serum albumin were cross-linked directly on the surface of a graphite electrode by glutaraldehyde. The sensor was used to determine putrescine at 0 mV (vs. Ag/AgCl reference electrode) in a potassium phosphate buffer (pH 7.4) solution containing 4 mM dopamine (3-hydroxytyramine). The response of putrescine was linear up to 600 μM with a standard deviation of 2.8%. The detection limit was 5 μM. The response time was around 30 s. The lifetime was over 30 days when the electrode was used every day. The interferences of cadaverine and spermidine could be eliminated by added dopamine which, apparently, inhibits the enzymatic conversion of these substrates more strongly than that of putrescine.
    Additional Material: 4 Ill.
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