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81.
82.
N J da Silva Júnior P R Griffin S D Aird 《Comparative biochemistry and physiology. B, Comparative biochemistry》1991,100(1):117-126
1. Elution profiles of 11 coral snake venoms, including those of Micrurus albicinctus, M. corallinus, M. frontalis altirostris, M. f. brasiliensis, M. f. frontalis, M. fulvius fulvius, M. ibiboboca, M. lemniscatus ssp., M. rondonianus, M. spixii spixii and M. surinamensis surinamensis, were compared using high performance gel filtration and reverse phase media. 2. Micrurus venom profiles were compared with those of "outgroup" taxa Bothrops moojeni, Naja naja kaouthia and Bungarus multicinctus. 3. Purified elapid venom constituents were also chromatographed under identical conditions in order to suggest possible identities of Micrurus venom constituents. 4. Masses of various components were confirmed by mass spectrometry. 5. Phospholipase constituents in three venoms were positively identified based on their reverse phase chromatograms. 6. Venoms of M. rondonianus and M. s. surinamensis are shown to be significantly different in their peptide composition from other Micrurus venoms. 相似文献
83.
84.
Marta E. Farías Ana M. Strasser de Saad Aída A. Pesce de Ruiz Holgado Dr. Guillermo Oliver 《Current microbiology》1991,22(4):205-211
l-Serine dehydratase fromLactobacillus fermentum was purified 100-fold. It was stabilized by the presence of 1 mM
l-cysteine in 50 mM phosphate buffer. Mr=150,000 was determined by gel filtration. The enzyme consists of four apparently identical subunits (Mr=40,000) that were observed after treatment with sodium dodecyl sulfate. The apparent Km forl-serine was 65 mM. Fe++ was required for the enzymatic activity, and the apparent Km value for this reaction was 0.55 mM. Maximum enzymatic activity was observed at 45°C and pH 8.0 in 50 mM phosphate buffer. At pH values different from the optimum, a positive cooperativity between substrate molecules was observed. The activation energy of the reaction was 11,400 and 22,800 cal × mol–1 for temperature values more than and less than 35°C respectively. The purified enzyme showed a maximum absorption between 400 and 420 nm, indicating the presence of pyridoxal-5-phosphate (PLP) as a prosthetic group. The PLP concentration was 0.027 µmoles per milligram of protein. The data suggest that there is 1 mol of PLP for each protein subunit. 相似文献
85.
Recombinant Trypanosoma cruzi antigens and Chagas' disease diagnosis: analysis of a workshop 总被引:1,自引:0,他引:1
M.J. Levin J. Franco da Silveira A.C.C. Frasch M.E. Camargo S. Lafon W.M. Degrave R. Rangel-Aldao 《FEMS microbiology letters》1991,89(1):11-20
Abstract A workshop organized by the Ibero-American Project of Biotechnology evaluated the diagnostic potential of several cloned Trypanosoma cruzi recombinant antigens for Chagas' disease serodiagnosis. A set of recombinants, Antigen 2, Antigen 13, SAPA, H49, A13, JL5, JL7, JL8, JL9, and RA1 provided by three different South American laboratories were probed with a panel of 236 South American serum samples. Antigens JL7, H49, Antigen 2, and A13 scored as the best diagnostic recombinant reagents. The results suggested that the main advantage of using cloned peptides for chronic Chagas' disease diagnosis resided in their highly specific immunoreactive properties. 相似文献
86.
T. R. Deason P. C. Silva S. Watanabe G. L. Floyd 《Plant Systematics and Evolution》1991,177(3-4):213-219
Komárek has recently reviewed the various species assigned to the green algal genusNeochloris
Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia.
Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class. 相似文献
87.
Application of flow karyotyping in prenatal detection of chromosome aberrations 总被引:1,自引:1,他引:0
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J W Gray B Trask G van den Engh A Silva C Lozes S Grell S Schonberg L C Yu M S Golbus 《American journal of human genetics》1988,42(1):49-59
This paper describes the application of bivariate flow karyotyping to (1) classification of chromosomes isolated from cultures of cells taken by amniocentesis and (2) detection of numerical and structural aberrations. Chromosomes were isolated from primary cultures 2-5 wk after amniocentesis, stained with Hoechst 33258 and chromomycin A3, and analyzed using dual beam flow cytometry. Information about chromosome DNA content and DNA base composition was derived from the locations of the peaks in the flow karyotypes, each peak being produced by one or more chromosome types with similar DNA content and DNA base composition. Information about the relative frequency of each chromosome type was determined on the basis of the relative volume of the peak for that chromosome type. Cytogenetic information determined on the basis of flow karyotypes was compared with that obtained by visual analysis following G-banding. Variability among the peak means and volumes in flow karyotypes was determined from analyses of 50 normal amniocyte cultures. Numerical aberrations involving chromosomes 21, 18, and Y were detected correctly in all of 28 analyses, including eight in a blind study. Structural aberrations involving chromosomes 1, 2, 3, 6, 9-12, 13, 14, 15, 21, and 22 were detected in all of seven cultures in a blind study. Flow karyotypes proved to be insensitive to small, normally occurring chromosome polymorphisms detected by banding analysis. In addition, a few samples were erroneously scored as having numerical aberrations. 相似文献
88.
Purification, characterization and induction of L-phenylalanine ammonia-lyase in Phaseolus vulgaris 总被引:1,自引:0,他引:1
A da Cunha 《European journal of biochemistry》1988,178(1):243-248
The enzyme L-phenylalanine ammonia-lyase was purified from leaves of Phaseolus vulgaris by Sephacryl S-200 gel filtration and Sepharose-4-B--succinyl-aminoethyl-L-phenylalanine affinity chromatography. L-Phenylalanine ammonia-lyase was specifically eluted from the affinity matrix with its substrate L-phenylalanine at 20-25 degrees C. The purified enzyme was shown to be homogeneous by gel electrophoresis both in presence and absence of SDS. Its Mr, determined by gel filtration and non-denaturing gel electrophoresis, was 320,000 +/- 9000 and 330,000 +/- 4000 respectively. After SDS electrophoresis only one band of Mr 83,000 +/- 4000 was detected, indicating that the enzyme is an oligomer containing four subunits. The pH optimum of enzyme activity was 8.8-9.2. Ampholyte isoelectrofocusing in polyacrylamide demonstrated the presence of a single charged species at pH 4.2. The homogeneous enzyme catalyzed the deamination of L-phenylalanine to trans-cinnamate but did not catalyze the transamination of L-phenylalanine to L-phenylpyruvate. The enzyme showed Km 1.25 mM for L-phenylalanine. Antibodies to homogeneous L-phenylalanine ammonia-lyase recognised specific epitopes on L-phenylalanine aminotransferase as demonstrated by immunoaffinity purification and immunoblotting. The induction of L-phenylalanine ammonia-lyase activity during phaseollin biosynthesis in the Phaseolus vulgaris--Colletotrichum lindemuthianum interaction was regulated by an increase in enzyme concentration resulting from an increase in de novo synthesis of L-phenylalanine ammonia-lyase protein. 相似文献
89.
Cytosolic and mitochondrial isoenzymes of aspartate aminotransferase (EC 2.6.1.1) were purified to homogeneity from chicken liver, without previous fractionation of the subcellular components. The procedure includes initial heat treatment and ammonium sulfate fractionation. The two isoenzymes can then be separated by a DEAE-Sepharose chromatography using a linear gradient of L-aspartate (reaction substrate). The separated fractions can be further purified by a parallel step with HA-Ultrogel prior to octyl-Sepharose (c-AAT) and CM-Sepharose (m-AAT) chromatographies. Michaelis constants, pI values, inhibition by adipate and subforms generation with time were studied for both isoenzymes. 相似文献
90.
R Wainstok de Calmanovici L C San Martín de Viale 《The International journal of biochemistry》1988,20(9):1015-1020
1. The porphyrinogenic ability of several antineoplastics used in the therapy of the different cancers was evaluated. The action of cyclophosphamide, busulfan and 5-fluorouracil on the amount and nature of the accumulated hepatic porphyrins and on the activity of delta-aminolaevulinate synthase (ALA-S), were estimated at different doses and times of drug treatment in 17-day-old chick embryos. 2. It was observed that cyclophosphamide produces a significant increase in the accumulation of hepatic porphyrins at different doses as well as in the activity of the ALA-S, at all the incubation times. Cyclophosphamide alters the pattern of porphyrins accumulated in the liver, where a coproporphyrin: protoporphyrin ratio higher than in the controls can be observed. 3. Busulfan increased the hepatic porphyrins accumulated in the liver but to a lesser degree than cyclophosphamide. 4. 5-Fluorouracil did not modify the hepatic porphyrin content when it was administered at doses up to 40 mg/embryo. 5. When the embryos were injected with busulfan or 5-fluorouracil no significant differences were observed in the activity of ALA-S up to 11 hr of incubation. 6. These results indicate that cyclophosphamide has a remarkable porphyrinogenic capacity in chick embryo while busulfan, notwithstanding the fact that it alters the haem pathway, it does so to a degree that does not impair the regulation of ALA-S activity. Fluorouracil seems to be non porphyrinogenic in this system, up to 40 mg/embryo. 相似文献