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  • 1
    Electronic Resource
    Electronic Resource
    Reversed micelles recognize an active protein (1996)
    Springer
    Biotechnology techniques 10 (1996), S. 141-144 
    Details
    ISSN: 1573-6784
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The extraction behavior of native and heated-denatured α-chymotrypsin has been investigated with two different reversed micellar systems. A large difference in the degree of extraction was observed for the native relative to the denatured α-chymotrypsin. In particular, mixed reversed micelles formulated with DOLPA (dioleyl phosphoric acid) and AOT show a high selectivity for the active α-chymotrypsin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00158935
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of serum fractions on single-cell mouse embryos in vitro (1987)
    Springer
    Journal of assisted reproduction and genetics 4 (1987), S. 153-158 
    Details
    ISSN: 1573-7330
    Keywords: serum ; fractions ; effects ; in vitro fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To examine the effect of various fractions of human fetal cord serum (HCS) on mouse embryos cultured in vitro, heat-inactivated HCS was separated by ultrafiltration into five distinct fractions: Fractions A, MW〉30,000; B, MW 30,000−10,000; C, MW 10,000−5000; D, MW 5000−1000; and E, MW 〈1000. Seven hundred twentyeight single-cell embryos were cultured in TYH- 280 medium supplemented with 8 mg/ml bovine serum albumin (BSA) and a 20% concentration of Fraction A, B, C, D, or E, whole HCS, or BSA alone. Embryos cultured with Fraction A or E or whole HCS demonstrated a significantly reduced growth rate (P〈0.01), while embryos cultured with Fraction D demonstrated a significantly increased growth rate (P〈0.01). Additionally, 649 singlecell embryos were cultured in medium which was supplemented with 8 mg BSA/ml and a 0, 1,2, or 5% concentration of Fraction A or E. Fraction E displayed toxicity even at a 1% concentration (P〈 0.07), while Fraction A demonstrated growth inhibition at a 5% concentration (P 〈0.05) but increased the hatching rate at a 1% concentration (P 〈 0.01). Finally, 635 single-cell embryos were cultured with four distinct fractions of HCS obtained from a Sephacryl S-200 column: Fractions I, MW 100,000; II, MW 70,000−100,000; III, MW 30,000−70,000; and IV, low molecular weight (〈5000). Fraction I or III significantly reduced the embryo growth rate as seen with Fraction A (P〈0.01) and Fraction II significantly increased only the hatching rate (P〈0.01), while Fraction IV significantly increased the growth rate as seen with Fraction D. In conclusion, HCS contains embryo growth inhibitory properties in the high (〉30,000) and low (〈1000) molecular weight components, while growth promoting factors are found in the 1000−5000 MW fraction. It also seems that there are some factors in the 70,000−100,000 MW fraction which may promote the ability of the embryo to hatch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01555462
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Oocyte maturation inhibitor activity in human follicular fluid: Quantitative determination in unstimulated and clomiphene citrate- and human menopausal gonadotropin-stimulated ovarian cycles (1986)
    Springer
    Journal of assisted reproduction and genetics 3 (1986), S. 218-223 
    Details
    ISSN: 1573-7330
    Keywords: OMI ; follicular fluid ; hMG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since removal of the oocyte from the intrafollicular milieu allows meiotic resumption and germinal vesical breakdown to proceed, the concept of an intrafollicular oocyte maturation inhibitor (OMI) has evolved. Accordingly, we asked the following questions: Is there OMI activity in human follicular fluid? Does OMI activity change with ovarian hyperstimulation? and Does OMI activity correlate with oocyte fertilization or the concentration of steroids in the corresponding follicular fluid? Fresh cumulus enclosed porcine oocytes from small follicles were incubated with human follicular fluid aspirates from normally menstruating patients with or without treatment: unstimulated follicles (N=10), clomiphene citrate (150 mg/day) (N=10)-treated cycles, and human menopausal gonadotropin (hMG) (N=12)-treated cycles. A lyophylized porcine follicular fluid standard and serum-free culture media were used as positive and negative controls, respectively. After a 40-hr incubation with test materials, the oocytes were fixed, stained, and evaluated for oocyte maturation as determined by germinal vesical breakdown. Human follicular fluid, estradiol, progesterone, androstenedione, and testosterone levels were determined by radioimmunoassay. The 50% inhibitory dose (ID50) for OMI activity in follicular fluid from untreated, spontaneously menstruating women was less than that for follicular fluid from clomiphene-stimulated patients, which was less than that for follicular fluid from hMG-stimulated patients. The difference between OMI values from untreated and hMG-stimulated follicular fluids was statistically significant. Human oocytes removed from follicular fluid with higher OMI activity tended not to fertilize in vitro compared to the relatively lower OMI activity present in follicular fluid yielding oocytes which did fertilize. However, these differences were not significant. Although there were no significant correlations between any of the follicular fluid concentrations of sex steroids and OMI activity, there was a trend toward higher androgen levels in follicular fluid with higher OMI activity. These findings lend support to the hypothesis that immature, nonfertilizable follicles obtained from spontaneously cycling women with or without exogenous gonadotropin treatment contain higher OMI activity levels than mature, fertilizable follicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01132807
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Protein refolding by reversed micelles utilizing solid-liquid extraction technique (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 620-623 
    Details
    ISSN: 0006-3592
    Keywords: protein refolding ; reversed micelles ; solid-liquid extraction ; RNase A ; DNA ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article reports that a reversed micellar solution is useful for refolding proteins directly from a solid source. The solubilization of denatured RNase A, which had been prepared by reprecipitation from the denaturant protein solution, into reversed micelles formulated with sodium di-2-ethylhexyl sulfosuccinate (AOT) has been investigated by a solid-liquid extraction system. This method is an alternative to the ordinary protein extraction in reversed micelles based on the liquid-liquid extraction. The solid-liquid extraction method was found to facilitate the solubilization of denatured proteins more efficiently in the reversed micellar media than the ordinary phase transfer method of liquid extraction. The refolding of denatured RNase A entrapped in reversed micelles was attained by adding a redox reagent (reduced and oxidized glutathion). Enzymatic activity of RNase A was gradually recovered with time in the reversed micelles. The denatured RNase A was completely refolded within 30 h. In addition, the efficiency of protein refolding was enhanced when reversed micelles were applied to denatured RNase A containing a higher protein concentration that, in the case of aqueous media, would lead to protein aggregation. The solid-liquid extraction technique using reversed micelles affords better scale-up advantages in the direct refolding process of insoluble protein aggregates. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 620-623, 1998.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Design of surfactants suitable for protein extraction by reversed micelles (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 26-32 
    Details
    ISSN: 0006-3592
    Keywords: reversed micelle ; microemulsion ; protein extraction ; surfactant ; bioseparation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New surfactants have been synthesized for potential use in reversed micellar protein extraction operations. Preferential solubility of the surfactant in an aliphatic solvent such as hexane, heptane, or isooctane and the formation of reversed micelles accompanied with solubilization of significant quantities of water can be achieved by using strongly hydrophobic, twin alkyl chains as the hydrophobic moiety. Different surfactants having identical water-solubilizing capacities can have significantly different behavior in protein extractions, where extraction efficiency appears to be governed by the nature of the interfacial complex that forms between surfactants and proteins. Bulky surfactant chains provide a steric hindrance to the adsorption of the surfactant to the protein surface, thus inhibiting solvation of the protein/surfactant complex, and hence protein extraction. Under these conditions, a precipitate forms either in the bulk aqueous phase or at the interface. Surfactants that can form a close-packed complex with the protein are excellent protein-solubilizing agents. Dioleyl phosphoric acid (DOLPA) appears to be the best surfactant currently available for protein extraction. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 54: 26-32, 1997.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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