摘要:

AbstractThreonine dehydratase has been purified about 200‐fold from extracts ofCandida maltosaby chromatography on DEAE‐cellulose, Sephadex G‐200, and hydroxylapatite. The enzyme is fairly stable in solution in the presence of 250 mM phosphate buffer containing 40% glycerol. The molecular weight of the native enzyme was calculated to be approximately 190,000. The molecular weight of a subunit of the enzyme was estimated to be 46,000 by SDS gel electrophoresis. The enzyme seemed to have a tetrameric structure consisting of four identical subunits. The enzyme is subject to feedback inhibition by isoleucine and is stimulated by valine and phosphate ions. Kinetic studies indicate that there are more than one binding site for each effector on the enzyme. It is concluded from these investigations that the binding sites for threonine as well as for isoleucine are distinct from another, whereas the binding sites for valine and phosphate are identical or closely overla

ISSN:0233-111X    

DOI:10.1002/jobm.3620260802

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620260803

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

摘要:

AbstractDifferent fragments of the maxicircle of the kinetoplast DNA (kpDNA) fromCrithidia oncopeltiwere cloned (Fig. 1, 2) and tested for ARS‐activity (ARS, autonomously replicating sequences). ARS‐avitivity was expressed as number of transformed yeast cells per μg plasmid DNA, as number of transformed cells per number of plasmid molecules (transformation efficiency, TE) and as number of transformed cells per kilobasepair of cloned kpDNA (specific transformation efficiency, TE8) (Fig. 3. Table 1). All DNA fragments studied showed ARS‐activity. Large fragments exhibited higher ARS‐activities than their smaller subfragments. The number of fragments showing ARS activity and their distribution within the maxicircles (Fig. 4) suggest that there was no strong correlation between sites with ARS‐activity and the replication origi

ISSN:0233-111X    

DOI:10.1002/jobm.3620260804

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620260805

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

摘要:

AbstractAfter using of the streptothricin antibiotic nourseothricin in animal husbandry for growth promotion, plasmid‐borne resistance to streptothricin could be observed inE. colifrom nourseothricin fed pigs, from emploees in pig farms and from their family members. Moreover, streptothricin resistance plasmids also occurred inE. coliof man without any contact to pig farms (gut flora and even urinary tract infections). However, these individuals live in villages and towns of the territory where nourseothricin was applied to pigs. Similar streptothricin resistance plasmids belonging to different incompatibility groups were found in bothE. colifrom pigs andE. colifrom human beings. As no coselection of resistance to drugs indispensable for therapeutic use in man was observed, the application of nourseothricin in animal husbandry has not clinical implication for human medicine yet. Nevertheless, this problem remains under further investigatio

ISSN:0233-111X    

DOI:10.1002/jobm.3620260806

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

摘要:

AbstractAlkaline phosphatase activity appeared inStreptomyces nourseistrain IMET 43 716 when cultures were shifted to phosphate limitation. By usingp‐nitrophenylphosphate as substrate, the activity detected at pH 9.4 was cell‐bound, as long as young mycelia were studied. Supernatant fluids of the cultures were only active, if partial mycelial lysis had taken place after incubation for several days under the influence of shear forces.After cytochemical staining the phosphatase reaction products were microscopically visible as grains distributed rather homogeneously within the hyphal lumen. The frequency of grains was correlated to the rate of nourseothricin production. Electron microscopy of thin sections showed the phosphatase reaction products to be only present in the cytopl

ISSN:0233-111X    

DOI:10.1002/jobm.3620260807

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

摘要:

AbstractThe autolytic process observed in fungi has been divided into three different phases A 1, A 2, A 3. Each of which is characterized by specific metabolic evants. Recently, we characterized these phases by means of14C‐d‐glucose. In this communication we report on the uptake and conversion of14C‐labelled amino acids. These amino acids were rapidly taken up by the fungal mycelium and incorporated into cellular pools. During autolysis phase A 1 these amino acids were still used for protein synthesis. The autolytic process resembled a turnover process during this first phase. At this time the mycelium still exhibited high metabolic activity. The second phase, A 2 was characterized by a rapid intracellular degradation of compartmental material and accompanied by oxidation of the products formed. This was reflected by an increasing14CO2production. During phase A 3 products of intracellular degradation and possibly compounds from autolysing hyphae were still taken up by intact, i. e. living compartments of the hyphae and converted to heat and CO2.Almost no radioactive material was released into the medium during the last two phases. Metabolically active compartments or parts of the hyphae were present during the whole process of autolysis of fungal batch culture, .i e. even at the end of phas

ISSN:0233-111X    

DOI:10.1002/jobm.3620260808

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

摘要:

AbstractThe present review deals with some essential aspects regarding to the microbial gibberellin biosynthesis during the last 10 to 15 years.After a brief historical outline some gibberellins resp. gibberellin‐like substances producing microorganisms (e. g. fungi, bacteria) are presented of which the ability to produce these compounds recently was published. In addition techniques to obtain mutants from the fungusGibberella fujikuroiby means of physical and chemical methods are described. A further topic of the survey is dedicated to the biosynthetic pathway of gibberellins in the fungusGibberella fujikuroias well as the regulation of this biosynthetic route. In this connection especially the dependence of the biosynthesis on environmental factors (e. g. role of various carbon and nitrogen sources in the medium and their relation to each other) are demonstrated.Also a possible role of the gibberellins for the producing fungus itself is discussed.Finally, new fields of application for gibberellic acid and the gibberellins GA4and GA7(e. g. animal production, pharmaceutical industry) are presente

ISSN:0233-111X    

DOI:10.1002/jobm.3620260809

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

ISSN:0233-111X    

DOI:10.1002/jobm.3620260810

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY

摘要:

AbstractBacteria capable of methylating Hg2+have been isolated from sediment, water, soil and the gastrointestinal tract of humans. However, very little is known about the physiology and genetics of the mechanisms controlling Hg2+methylation. Mercury methylation can be either chromosomal or plasmid‐encoded in bacteria. In addition, the extent of nonbiological methylation is not well understood in environmental samples, where there are numerous physical, chemical and biological factors that control the methylation process.It is known that methylation of Hg2+is mediated by a series of enzymatic reactions that are also responsible for the anaerobic evolution of methane. However, under highly reduced environments the reaction can also occur nonbiologically. It is possible that certain bacteria use methylation as a resistance/detoxification mechanis

ISSN:0233-111X    

DOI:10.1002/jobm.3620260811

出版商:Wiley‐VCH    

年代:1986

数据来源: WILEY