摘要:

The presence of two alkaline phosphatases in mycelial extracts ofNeurospora crassais demonstrated. The two enzymes differ in molecular weight, electrophoretic mobility, and their response to some cations. Neither enzyme is identical with the phosphatase, repressible by inorganic phosphate, known to be present inNeurospora. Both enzymes have an absolute requirement for Zn2+, which is tightly bound to the protein and cannot be replaced by any other ion tested, and for Mg2+, which is loosely bound and can be at least partially replaced by several other ions. The possibility that the two activities represent different states of aggregation of the same subunits rather than two different proteins is discussed.

ISSN:0008-4166    

DOI:10.1139/m69-080

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The relative heat stabilities of the glycolytic enzymes and 6-phosphogluconate dehydrogenase from autolysates of the mesophileC.pasteiirianumand the two thermophilesC.tartarivorumandC.thermosaccharolyticumare compared. Pyruvate kinase from all three organisms is quite stable at elevated temperatures. All other enzymes studied from the thermophiles show less susceptibility to heat inactivation than the corresponding enzymes from the mesophile.

ISSN:0008-4166    

DOI:10.1139/m69-081

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

For the first time nonformylated tetrahydrofolic acid is shown to be a major form of folic acid in rat liver, along withN5-methyltetrahydrofolic acid. A system of differential microbiological assays that will identify the folates occurring naturally in tissues is presented. It involves rapid heat inactivation of natural enzymes, cleavage of folate polyglutamates with conjugase, and assay with three microorganisms under standardized conditions that allow identification and quantitation of both free and conjugated forms of four folate derivatives. Evidence is presented that the procedures outlined produce a minimum of change in the naturally occurring folate derivatives.

ISSN:0008-4166    

DOI:10.1139/m69-082

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Four sets, each of 100 bacterial isolates, were derived from two different flax rhizosphere and corresponding control (nonrhizosphere soil) samples. A two-stage principal component analysis was used to compare the nature and properties of these bacterial cultures which were selected by a random sampling method from primary isolation plates. These 400 experimental isolates were characterized by their reaction to a set of 98 tests. Principal component analysis was applied separately to the data for each of the four sets of cultures. The sets were then compared both in terms of the leading discriminating tests and of the detailed properties of the clusters of isolates detected. Because these isolates and a set of 100 named cultures (previously studied) were subjected to the same tests, the properties of groups of isolates from different sets could be directly compared. The kinds of isolates predominant in the rhizosphere samples were not represented amongst isolates derived from the corresponding control soil populations. The specific kinds of amino-acid-requiring isolates present in the control soil populations were not found in the corresponding rhizosphere populations. The two control soil sets of isolates (predominantly arthrobacter–coryneform-like organisms) were generally similar in their reactions to the tests used, but the two sets of rhizosphere isolates (predominantly pseudomonas-like organisms) were relatively dissimilar. The named species studied previously were not sufficiently indicative of the diversity found in the experimental isolates: this was especially true of the arthrobacter-like isolates. The numerical analyses yielded useful groupings of tests and of cultures and aided in their evaluation.

ISSN:0008-4166    

DOI:10.1139/m69-083

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Sensitivity to the antibiotic actinobolin was restored in an actinobolin-resistant strain ofEscherichia coliby exposing cells of the resistant strain to an aqueous solution of ethylenediaminetetraacetic acid (0.0004 M) for 10 minutes at 37 °C. This observation suggests that decreased permeability to actinobolin is one mechanism by whichE.colimay resist inhibition by this antibiotic.

ISSN:0008-4166    

DOI:10.1139/m69-084

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The DNA base composition (expressed as mean molar percentages of guanine and cytosine) of 25 strains ofRhizobium japonicumwas determined to study the genetic relatedness of these strains. The mole percentage GC ranged from 61.47 to 64.09. Statistical analysis of the DNA base ratios of the 25 isolates revealed that 16 of these differed significantly in GC ratios from some of the other strains.

ISSN:0008-4166    

DOI:10.1139/m69-085

出版商:NRC Research Press    

年代:1969

数据来源: NRC