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  • Biochemistry and Biotechnology  (9)
  • Steroids  (5)
  • 1990-1994  (14)
  • 1960-1964
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 37 (1991), S. 627-638 
    ISSN: 0006-3592
    Schlagwort(e): solubility parameters ; hydrophobicity index ; Hansen parameter ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Widespread commercial application of enzymes as catalysts for specialty or commodity chemical synthesis will require their use in nonaqueous systems. While a number of non-aqueous enzyme applications have been demonstrated, the lack of useful rules for predicting enzyme-solvent interactions has hindered the development of this technology. Both Hildebrand and solvent hydrophobicity (octanol-water partition coefficient) parameters have been used previously to correlate and predict enzyme activity in nonaqueous systems, with some success, but any single-parameter approach is inherently limited in its ability to reflect the spectrum of possible enzyme-solvent interactions. Therefore, this study evaluates the three-dimensional solubility parameter space, as proposed by Hansen, to correlate and predict enzyme activity in microaqueous, miscible, and biphasic nonaqueous systems. Preliminary results suggest that Hansen parameters may be useful for correlating nonaqueous enzyme activity, and that the dispersive and polar parameters may be disproportionately important in single-phase microaqueous systems. The Hansen hydrogen-bonding parameter appears to be the only parameter yet evaluated capable of correlating the water requirement for enzyme activity in microaqueous systems, suggesting that water affects protein structure through enthalpic rather than entropic processes in nonaqueous systems. Insufficient data are available for miscible and biphasic systems, but it is proposed that enzyme activity may correlate with the average solubility parameters of miscible systems and of the aqueous phase in biphasic systems.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 1049-1052 
    ISSN: 0170-2041
    Schlagwort(e): Steroids ; α-Hydroxyenamides ; Neighbouring group participation ; Dienealdehydes ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: During reduction with sodium tetrahydroborate the 2-[acetyl-(alkyl)aminomethylene]-3-keto steroids 1aa, ba and 2aa - ca undergo transformation into the 2,4-diene-2-aldehydes 5a and 6, respectively. These compounds are the decomposition products of the cyclic orthoester amides of the type 4a, b, formed by NAc-6 neighbouring group participation from the 3-hydroxy derivative A, which cannot be isolated.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1990 (1990), S. 419-422 
    ISSN: 0170-2041
    Schlagwort(e): Steroids ; Estra-1,3,5(10)-trien-17-ol derivatives ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The four possible isomers of 16-hydroxymethyl-3-methoxyestra-1,3,5(10)-trien-17-ol 5a, 6a, 7a, 8a were converted into the corresponding 16-methyl analogues 4a, 11a, 12a, 13a, which were characterized from their 1H- and 13C-NMR spectra. The results permit a configurational correlation with 16-methyl derivatives reported in the literature.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 8 (1990), S. 227-232 
    ISSN: 0263-6484
    Schlagwort(e): Energy-consuming processes ; rat hepatocytes ; oxygen consumption ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A method for the quantification of energy consuming processes described by Siems et al.6 for reticulocytes and by Müller et al.10 for ascites tumour cells was applied to balance the ATP-consumption of isolated rat hepatocytes. On the basis of decreased coupled respiration rates following the specific inhibition of energy-requiring reactions, the energy demands of protein turnover, nucleic acid synthesis, Na+/K+-ATPase and Ca2+-transport of hepatocytes in different incubation media were assessed. These processes together with urea synthesis account for about 60 per cent of the total energy consumption in a glucose and amino acid-enriched Eagle/Borsook medium. The metabolic flux rates of total ATP-consumption and ATP-consumption of single energy-requiring processes in hepatocytes are compared with those in reticulocytes and different tumour cell types.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 923-925 
    ISSN: 0170-2041
    Schlagwort(e): Steroids ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The four possible stereoisomers of 3-methoxy-16-methyloestra-1,3,5(10)-trien-17-ol (1, 2, 3, 4) were converted into the corresponding 16-methyl-19-nortestosterone analogs (5, 6, 7, 8), which were characterized by their 1H- and 13C-NMR spectra. The coupling constants J16,17 and the characteristic 13C signals (C-12, C-17, C-18, 16-CH3) clearly confirmed the configurations at C-16 and C-17.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Apolipoprotein B-100 is the principal protein component of lipoproteins with very low, intermediate, and low density. The interaction of apoB-100 with low density lipoprotein (LDL) receptors is responsible for the uptake of LDL into cells. An AT-rich hypervariable region is located adjacent to the 3′ end of the apoB gene. It consists of a variable number of tandemly repeated sequences (VNTR). Two approaches were used to analyze this polymorphism. In both, the region harboring the VNTR was amplified with the polymerase chain reaction (PCR). In the first method, fluorescently labeled primers were used in the PCR reactions and products were separated in agarose gels by means of an automated fluorescent fragment analyzer. In the second method, PCR products were analyzed in denaturing polyacrylamide gels and detected with silver staining. Even in the highly sophisticated automated system, agarose gel electrophoresis did not always enable unequivocal assignment of VNTR alleles. In contrast, denaturing polyacrylamide gel electrophoresis made it possible to distinguish the 15 bp differences between the VNTR alleles in a precise and simple manner. The VNTR polymorphism was typed in 234 individuals. Among these were 136 patients with coronary artery disease and 74 healthy controls. Thirteen alleles could be distinguished. The allele containing 49 repeats (VNTR-49) was found in 9.2% of the coronary artery disease patients and in 4.7% of the controls. Thus, the VNTR-49 allele increases relative coronary risk by about twofold. It is concluded that the apoB VNTR polymorphism is a potentially useful genetic marker. Since agarose gel electrophoresis may lead to ambiguous results, we prefer typing by denaturing polyacrylamide gel electrophoresis. This has to be accounted for, especially if the apoB VNTR polymorphism is applied to forensic studies.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: To study the clonal events occurring during ontogeny of the humoral immune system, we evaluated plasma immunoglobulin (Ig) production in term newborns and young children by high-resolution two-dimensional gel electrophoresis. The clonality pattern of Ig light (L) chains from healthy newborns (n = 19) was similar to that observed on protein maps of their mothers or of normal adults (n 〉 100), that is, rare distinguishable small spots in a cloud-like large band of indiscrete Ig L chain spots (polyclonal pattern; maternal Igs). Analysis of plasma samples obtained from infants between 1 month and 5 years of age (n = 55) revealed discrete but evident alterations of the clonality of Ig production. Between the 2nd and 4th months of life, transient attenuation of the “polyclonal background” was observed in association with the appearance of an increasing number of well-resolved Ig L chain spots (corresponding to plasma Ig concentrations between 0.5 and 1 g/L per spot). This “restricted” clonal pattern was progressivly less apparent on protein maps of infants older than 2 year and evolved towards a “normal” adult polyclonal pattern at the age of 5. These results suggest that the development of the B-cell clones is heterogeneous, either through limited outgrowth of precursor cells or through selective antigenic pressures.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 1103-1107 
    ISSN: 0170-2041
    Schlagwort(e): Steroids ; 15-Hydroxymethylene-16-ketosteroids ; D-seco-steroids ; D-Homo-oxa-steroids ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In alkaline medium, 17β-hydroxy-15-(hydroxymethylene)androst-5-en-16-one (2a) is cleaved in two ways to give D-seco compounds. Dilute bases in protic solvents cause 1,3-dicarbonyl splitting to the 15-formyl-15,16-seco-16-oic acid 3, while the use of sodium methanolate in benzene solution gives rise to 16,17-splitting to afford the 15-formyl-16,17-seco-16,17-dioic acid 5. Both seco compounds readily undergo lactolone ring closure to give 4a and 6a, respectively. The malonaldehyde moiety of 5 is transformed in two directions: either loss of the formyl group to give 3β-hydroxy-16,17-secoandrost-5-ene-16,17-dioic acid (7a) or decarboxylation to 3β-hydroxy-16-oxo-16,17-secoandrost-5-en-17-oic acid (9) is observed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1993 (1993), S. 1057-1062 
    ISSN: 0170-2041
    Schlagwort(e): 17β-Marsdenin ; Pregnane derivatives ; Biosides ; Gongronema latifolium ; Asclepiadaceae ; Steroids ; Saccharides ; Carbohydrates ; Glycosides ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Four New Pregnane Glycosides from Gongronema latifolium (Asclepiadaceae)Four so far unknown pregnane biosides have been isolated from the chloroform extract of the leaves of Gongronema latifolium Benth. et Hook. (Asclepiadaceae). From one- and twodimensional NMR experiments (NOE difference spectroscopy, ROESY, H,H-COSY, C,H-COSY, HMBC) their structures have been established as 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-canaropyranosyl]-17β-marsdenin (1a), 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl]-17β-marsdenin (1b), 12-O-acetyl-3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-canaropyranosyl]-17β-marsdenin (1c) and 11-O-acetyl-3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-canaropyranosyl]-17β-marsdenin (1d).
    Zusätzliches Material: 7 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: High-resolution two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was used to analyze serum samples and purified immunoglobulins (Ig) obtained from “normal” individuals and from patients diagnosed with monoclonal gammopathies (MG) (n = 47; 5 IgA, 15 IgM, 15 IgG, 4 biclonal IgG, 1 IgD, 7 Bence Jones proteins). Polyclonal and monoclonal heavy (H) chains were located at different restricted gel positions according to their isotype. Monoclonal H chains appeared as sets of spots characterized by charge (pI) and size (Mr) microheterogeneity. Most of the monoclonal gamma chains were not seen on the gels (12/15). Supplementary polypeptides of 45-48 kDa were detected in serum samples containing monoclonal IgM, but were not seen in MG of other isotypes. However, these polypeptides were not specifically associated with monoclonal IgM because they were also found on protein maps of purified polyclonal IgM. Polyclonal light (L) chains appeared as cloudy bands containing several zones of higher density, whereas monoclonal L chains were usually resolved as single sharp spots. In 6 samples, monoclonal L chains were not seen, and in 9 samples, they appeared as two or more spots, characterized by different pI and/or Mr. In one sample obtained from a patient with a biclonal gammopathy, the L chains were resolved as 4 different spots. Our results confirm that 2-D PAGE is an excellent tool to study Ig. Analysis of the L chain region of the gels was particularly informative. Several monoclonal L chains exhibited heterogeneous two-dimensional spot patterns, suggesting that “subtile” clonal mutations of B-cell lineage and/or posttranslational modifications were involved in their production.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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