To clarify the relationship between the substrate structure and enzyme activity, substrate specificity of ATP deaminase from Microsporumaudouini was examined in detail, in using 35 kinds of adenine compounds. 5′-ATP, 5′-ATPP, 5′-ADP, 5′-Ad-sulfate, 5′-ADP-ribose, 5′-AMP and 5′-ADP-glucose were rapidly deaminated in this order. Adenosine was deaminated at a slow rate, but adenine was not deaminated. This enzyme also catalyzed the deamination of 3-iso-AMP and the dechlorination of 6-chloropurine riboside. The C′-1 or C′-2 position of ribose is necessary for binding to the enzyme, and the negatively charged group such as phosphate or sulfate at the 5′-position of ribose is most essential for the effective deamination. A probable schematic model showing the relationship between this enzyme and substrate was presented.
Agents capable of eliminating F8-episome from a male strain of Escherichia coli were selected by two methods. The first method was based on the conversion of the strain from galactose fermentative to non-fermentative and the second on the conversion from RNA phagesensitive to resistant. Two antibiotics, sarkomycin and primocarcin, were selected. Sarkomycin was less active than acridine orange, but was less toxic.
A number of Streptomyces strains degraded the N-glycosidic linkage of pyrimidine nucleotides. The products and some conditions of 5′-UMP degradation were studied using cell-free extracts of Streptomycesvirginiae IFO 3729. Formation of uracil was recognized by paper electrophoresis and by the shift of ultraviolet absorption at an alkaline pH. Pentose phosphate was purified by ion-exchange chromatography and prepared as Ba salt. It was identified with R5P by paper chromatography, paper electrophoresis and by chemical analyses. Optimum pH and temperature for R5P formation were 5.5 and 55°, respectively. 5′-UMP was quantitatively converted to uracil and R5P under this condition. At near neutral pH and at lower temperatures, the rate of R5P formation was far lower than that of uracil, caused by coexisting R5P-metabolizing activity. When the mixture of purine and pyrimidine nucleotides was subjected to the enzyme action, pyrimidine nucleotides were selectively degraded
A novel enzyme, pyrimidine 5′-nucleotide phosphoribo (deoxyribo) hydrolase, which hydrolyzes the N-glycosidic linkage in pyrimidine 5′- ucleotides to pyrimidine bases and pentose-5-phosphates, was extracted and purified to about 31-fold from the cells of Streptomyces virginiae and its properties were examined. The purified enzyme hydrolyzed 5′-UMP, 5′-CMP, 5′-deoxyUMP, 5′- deoxyTMP and 5′-deoxyCMP. Purine 5′-nucleotides were degraded by the crude extracts, but this activity was removed by the purification. Nucleosides and 3′-nucleotides of purines and pyrimidines were never cleaved even by the crude extracts. 2′-O-methyl-5′-UMP was also resistant to the enzyme reaction. The Km value for 5′-UMP was 6.95×10-3M. Co-factors of low molecular weight were unnecessary for the reaction. Phosphate, pyrophosphate and ATP had little stimulatory effect on the reaction. The enzyme was relatively heat stable between pH 5.5 and 8.8. The activity remained unaffected after heating the enzyme solution at 65° for 45min. Ca++ had a marked stabilizing effect on the enzyme.
The taxonomical characters of 208 strains of glutamic acid-producing bacteria and the base compositions of DNA solated from representative strains were studied. These organisms are, in general, Gram-positive, non-sporulating, non-motile, ellipsoidal spheres to short rods, pleomorphic and require biotin for growth and accumulate aerobically large amounts of L-glutamic acid. Some minor differences are found in physiological characteristics of these strains. All strains examined are considered to belong to a single or very closely related species in genus Corynebacterium. They can beclassifiedphysiologically into 12 types. The guanine plus cytosine (G-C) content of DNA of these strains is varied as represented by three groups, groups I, II and III, G-C contents of which are 53, 56 and 65%, respectively. Group I contains most of the glutamic acid-producing strains and consists of the strains of the physiological types 1 to 10. On the other hand, those strains of groups II and III, which belong to physiological types 11 and 12, are different from those of group I in base composition of DNA. Although it is questionable whether the strains belonging to groups II and III could be assumed to belong to the same species as those belonging to group I, we consider it admittable to name all these organisms Corynebacterium glutamicum laying a stress on their common character of glutamic acid production.
An arginine auxotrophic mutant strain RN-362 was derived from Corynebacterium hydrocarboclastus R-7 and accumulated a large amount of L-ornithine at the expense of hydrocarbons. In order to establish the optimum culture condition for L-ornithine production, influences of the following factors were studied: arginine concentration, nitrogen sources, carbon sources, hydrocarbon content, and supplement of yeast extract and amino acids. The highest level of L-ornithine accumulation was attained after 80-hr cultivation and it amounted to about 9g per liter of the culture medium, which contained initially 10% (v/v) n-tetradecane as the carbon source. The maximum yield obtained corresponded to 32.5% (w/w) of n-tetradecane supplied, when 1% (v/v) n-tetradecane was added to the medium as a sole source of carbon.
An apparatus "Bioscanner", which is able to record automatically growth curves of 21 samples as a lot, was constructed. This has a scanning device with a shiftable light source connected with a photocell. The cultivation is carried out in L-form tubes fixed on a holder, which is placed in a rolling water bath. Growth curves of 21 specimens are recorded on an endless chart. A linear relationship between transmission value and the logarithm of cell density can be hold at the range of 15% to 100% transmission. Some examples of characteristic growth curves are presented employing test organisms of different properties.