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Fumarate reductase of Escherichia coli. Elucidation of the covalent-flavin component. 总被引:5,自引:0,他引:5
Fumarate reductase is a membrane-bound terminal oxidase which is induced when Escherichia coli is grown anaerobically. The purified enzyme is composed of two polypeptide chains of 69,000 and 24,000 daltons and contains 1 mol of covalently bound flavin adenine dinucleotide per mol of enzyme. Fluorescence scanning of SDS-polyacrylamide gels of the protein shows that the flavin is attached to the large subunit. The hypsochromic shift of the 372 nm band of riboflavin to 350 nm in both native fumarate reductase and a flavin peptide released by proteolytic digestion indicates that the flavin is attached via position 8 alpha of riboflavin. Based on the spectral properties and pH-fluorescence dependence we have identified the linkage as 8 alpha-[N(3)-histidyl]FAD. 相似文献
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Using terminal restriction fragment length polymorphism (T-RFLP) to identify mycorrhizal fungi: a methods review 总被引:1,自引:0,他引:1
Terminal restriction fragment length polymorphism (T-RFLP) is an increasingly widely used technique in mycorrhizal ecology.
In this paper, we review the technique as it is used to identify species of mycorrhizal fungi and distinguish two different
versions of the technique: peak-profile T-RFLP (the original version) and database T-RFLP. We define database T-RFLP as the
use of T-RFLP to identify individual species within samples by comparison of unknown data with a database of known T-RFLP
patterns. This application of T-RFLP avoids some of the pitfalls of peak-profile T-RFLP and allows T-RFLP to be applied to
polyphyletic functional groups such as ectomycorrhizal fungi. The identification of species using database T-RFLP is subject
to several sources of potential error, including (1) random erroneous matches of peaks to species, (2) shared T-RFLP profiles
across species, and (3) multiple T-RFLP profiles within a species. A mathematical approximation of the risk of the first type
of error as a function of experimental parameters is discussed. Although potentially less accurate than some other methods
such as clone libraries, the high throughput of database T-RFLP permits much greater replication and may, therefore, be preferable
for many ecological questions, particularly when combined with other techniques such as cloning. 相似文献
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ANDRÉIA SILVA FLORES RÉA M. CORRÊA ELIANA R. FORNI-MARTINS ANA M. G. AZEVEDO TOZZI 《Botanical journal of the Linnean Society. Linnean Society of London》2006,151(2):271-277
Chromosome numbers were counted for 23 species of Crotalaria native to Brazil. Among these data there were new counts for 15 taxa, and some confirmed previous reports or represented numbers that were different from those cited previously. The chromosome numbers most frequently found were 2 n = 16 and 2 n = 32. Only C. incana L. had 2 n = 14 and C. tweediana Benth. had 2 n = 54. The counts 2 n = 32 and 54 were found in species of section Calycinae and 2 n = 16 and 14 in species of section Chrysocalycinae . The data revealed the importance of chromosomal parameters in the characterization of sections Calycinae and Chrysocalycinae in Brazil. We discuss the systematic significance and evolutionary aspects for the genus, comparing the results with the two sections that are native in Brazil. © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 271–277. 相似文献