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141.
T Kleinschmidt K P Rücknagel R E Weber B F Koop G Braunitzer 《Biological chemistry Hoppe-Seyler》1987,368(6):681-690
The hemoglobin of the Free-Tailed Bat Tadarida brasiliensis (Microchiroptera) comprises two components (Hb I and Hb II) in nearly equal amounts. Both hemoglobins have identical beta-chains, whereas the alpha-chains differ in having glycine (Hb I) or aspartic acid (Hb II) in position 115 (GH3). The components could be isolated by DEAE-Sephacel chromatography and separated into the globin chains by chromatography on carboxymethyl-cellulose CM-52. The sequences have been determined by Edman degradation with the film technique or the gas phase method (the alpha I-chains with the latter method only), using the native chains and tryptic peptides, as well as the C-terminal prolyl-peptide obtained by acid hydrolysis of the Asp-Pro bond in the beta-chains. The comparison with human hemoglobin showed 18 substitutions in the alpha-chains and 24 in the beta-chains. In the alpha-chains one amino-acid exchange involves an alpha 1/beta 1-contact. In the beta-chains one heme contact, three alpha 1/beta 1- and one alpha 1/beta 2-contacts are substituted. A comparison with other chiropteran hemoglobin sequences shows similar distances to Micro- and Megachiroptera. The oxygenation characteristics of the composite hemolysate and the two components, measured in relation to pH, Cl-, and 2,3-bis-phosphoglycerate, are described. The effect of carbon dioxide on oxygen affinity is considerably smaller than that observed in human hemoglobin, which might be an adaptation to life under hypercapnic conditions. 相似文献
142.
B. Müller E. Schlichting L. Bischoff K. Schügerl 《Applied microbiology and biotechnology》1987,26(1):36-41
Summary Penicillin G was extracted from a model medium with a secondary amine (Amberlite LA-2) as carrier in n-butylacetate as solvent in a 7.6 m high pilot plant Karr-column at different stroke frequencies, throughput of the phases, concentrations of Penicillin G and carrier and ratios of the throughputs of the aqueous and organic phases. Up to penicillin concentrations of 30 gl–1, throughputs of the aqueous phase of 100 lh–1 and throughput ratios of the aqueous phase-to-organic phase of 3, very high degrees of extraction (99%) can be achieved with a penicillin loss below 1%.Symbols a
specific interfacial area with regard to the volume of the continuous phase
- C
partition coefficient
- cA, cA, i
concentration of carrier (sec. amine) in the bulk at the interface
- cAHP, cAHP, i
concentration of complex in the bulk at the interface
- cH
proton concentration
- cHPa, cHPa,i
concentration of free acid in the bulk of the aqueous phase at the interface
- cHPo, cHPo, i
concentration of free acid in the bulk of the organic phase, at the interface
- cP, cP, i
concentration of acid anions in the bulk of the aqueous phase, at the interface
- d32
Sauter droplet diameter
- E
degree of extraction
- f
stroke frequency
- KG
reaction equilibrium constant
- Kphys
distribution coefficient
- N
number of stages in cascade
- t
mean residence time of the aqueous phase
-
aq
throughput of the aqueous phase
-
o
throughput of the organic phase
- Z
dimensionless longitudinal coordinate of the column with regard to its active length (4 m)
-
holdup of the organic phase 相似文献
143.
B. Müller E. Schlichting L. Bischoff K. Schügerl 《Applied microbiology and biotechnology》1987,26(3):206-210
Summary Penicillin G was extracted from mycelfree fermentation broths by means of the carrier (Amberlite LA-2) in n-butylacetate at pH 5 in a 7.6 m high pilot plant Karr-column with degrees of extraction E=98–99% and penicillin enrichments up to 3. The reextraction was carried out with phosphate buffer at pH-values above 7.5 with degree of extractions E=86–88% and penicillin enrichments up to 3. The penicillin and carrier losses were negligible. The influence of the process variables on the extraction degree was investigated. The penicillin extraction of the model medium and the fermentation broths were compared. Recommendations are given for the optimal penicillin recovery with reactive extraction.Symbols a
specific interfacial area with regard to the volume of the continuous phase
- cA
concentration of carrier
- cAHP,O
concentration of complex in feed
- cP,cP,O
concentration of penicillin acid anion in theaqueous phase, in the feed
-
d
32
Sauter droplet diameter
-
E
degree of extraction
-
f
stroke frequency
-
V
aq
throughput of the aqueous phase
-
V
0
throughput of the organic phase
-
Z
dimensionsless longitudinal coordinate of the column with regard to its active length (4m)
-
holdup of the organic phase 相似文献
144.
An enzyme-linked immunosorbent assay (ELISA) of the "sandwich-type" for sex hormone binding globulin (SHBG) has been developed. A rabbit anti-SHBG antibody (RAb) is immobilized to the microtitre plate. After incubation with standards and samples a second monospecific rabbit anti-SHBG antibody, labelled with alkaline phosphatase is added (RAb). Following further washing substrate is added, colour developed and the plate read at 405 nm wavelength on a standard ELISA plate reader. The assay is not influenced by the presence of steroids at the binding site, and shows good agreement to SHBG binding capacity assay and commercially available IRMA. Its sensitivity, specificity and precision allows its use in the routine laboratory. The SHBG ELISA has been used to measure SHBG concentrations in sera of normal men, women, pregnant women, and women receiving high-dose medroxyprogesterone acetate as a treatment of metastatic breast cancer. 相似文献
145.
Mohammed Safwat Abdel-Salam Walter Klingmüller 《Molecular & general genetics : MGG》1987,210(1):165-170
Summary A method for transposon mutagenesis in Azospirillum lipoferum 29708 is reported with transposon Tn5. The suicide plasmid pSUP2021 was used to deliver Tn5 in A. lipoferum using Escherichia coli SM10 as the donor. Neomycin-resistant transconjugants were detected at a frequency of 6x10-6 per recipient. Different types of mutants were isolated, e.g. auxotrophic, coloured, IAA-negative, and IAA-overproducers. Among the auxotrophic mutants, cysteine and methionine requirers prevailed. Random Tn5-insertion with only one copy per mutant was demonstrated by Southern blotting and hybridization. Tn5-induced mutants are relatively stable, with reversion rates of 2–20×10-8. A gene which is a part of the carotenoid pathway is closely linked to the histidine genes. The existence of two pathways for IAA production in A. lipoferum is discussed. 相似文献
146.
147.
NAD(P)H oxidase and peroxidase activities in purified plasma membranes from cauliflower inflorescences 总被引:5,自引:0,他引:5
An NAD(P)H oxidase activity stimulated by phenolic compounds has been investigated in purified plasma membranes (pm) and in an intracellular membrane (icm) fraction depleted in plasma membranes, both obtained from a microsomal fraction from cauliflower inflorescences ( Brassica oleracea L.). The phenolic compounds salicylhydroxamic acid (SHAM), ferulic acid, coniferyl alcohol, n -propyl gallate, naringenin, kaempferol and caffeic acid all strongly stimulated the activity. Peroxidase (EC 1.11.1.7), or a peroxidase-like enzyme, was responsible for the NAD(P)H oxidase activity, which proceeded through a free-radical chain reaction and was inhibited by catalase (EC 1.11.1.6), superoxide dismutase (EC 1.15.1.1) and KCN. Most of the total activity was soluble; however, the membrane-bound activity was highly enriched in the pm compared to the icm. The catalase activity was 6 times higher in the icm-fraction than in the pm-fraction, but this was not the reason for the much lower phenol-stimulated NADH oxidase activity in the icm. Peroxidase activity measured with o -dianisidine and H2 O2 had about the same specific activities in the pm-and icm-fractions.
Neither the phenol-stimulated NADH oxidase nor the peroxidase activity could be washed away from the pm even by 0.7 M NaCl, indicating that these activities are truly membrane-bound. SHAM as well as the other phenolic compounds capable of stimulating the NADH oxidase reaction were potent inhibitors of blue light-induced cytochrome b -reduction in the pm fraction. 相似文献
Neither the phenol-stimulated NADH oxidase nor the peroxidase activity could be washed away from the pm even by 0.7 M NaCl, indicating that these activities are truly membrane-bound. SHAM as well as the other phenolic compounds capable of stimulating the NADH oxidase reaction were potent inhibitors of blue light-induced cytochrome b -reduction in the pm fraction. 相似文献
148.
149.
Measurements in nearly monoenergetic beams of 144, 24.5, and 2 keV neutrons and of thermal neutrons have been performed with low-pressure proportional counters. The suitability of a tissue-equivalent proportional counter (TEPC) for dosimetry of low-energy neutrons has been investigated. In contrast to higher neutron energies, the modification of the primary radiation field by the detector wall and the contribution of secondaries produced in the gas are significant. These effects have been investigated by additional measurements with a carbon-walled proportional counter. The various physical processes of neutron interaction with wall and gas of the TEPC have been analyzed, and absorbed dose, kerma, and kerma contributions from the various processes are presented. In addition, dose contributions from contaminating neutrons and photons have been obtained for the calibration fields used. The results have been related to neutron fluence. The comparison with tabulated kerma factors shows excellent agreement, indicating the suitability of the TEPC method for dosimetry of low-energy neutrons. 相似文献
150.