Biochemical Studies on “Bakanae” Fungus

The production of gibberellin A₇ by Gibberella fujikuroi was studied by using newly devised assay method. Gibberellin A₇ increased at preferable temperature range between 32°C and 34°C at the controlled pH(6.0~7.5). The improved isolation process by using column chromatography composed of granular charcoal was found to be extremely convenient, because of its quick elution with satisfactory separation from gibberellic acid which is always accompanied by gibberellin A₇ in culture medium.     

Biochemical Studies on “Bakanae” Fungus. Part 54

Phosphate compounds in potato tubers were fractionated by ion-exchange chromatography. By the use of radio-phosphorus, the following compounds were tentatively identified to be present in potato tubers: G-1-P, G-6-P, F-6-P, FDP, PGA, AMP, UMP, ADP, UDPX, UDPG and ATP. When the tubers were stored at a low temperature, the contents of organic phosphate compounds showed a considerable increase over those of potatoes stored at a high temperature. However, the relative composition of each component was not much influenced by the storage temperature except ATP which showed a great increase at a lower temperature.     

Biochemical Studies on “Bakanae” Fungus. Part 51–53

The outline of this report has already been published in this Journal as a communication to the Editors. The relation among four isomers, gibberellin A₁, gibberellin C, pseudogibberellin A₁ and isogibberellin A₁ was clarified. The partial structure of gibberellin C is presented.     

Biochemical Studies on “Bakanae” Fungus. Part 48–50

The outline of this report has already been published in this Journal appearing under “Communication to the Editors” A new gibberellin which was named gibberellin A₄ was isolated and characterized.     

Biochemical Studies on “Bakanae” Fungus. Part 56–57

To confirm the location of the lactone ring at ring A of gihberellin A₃, selenium de-hydrogenation experiments were conducted in various ways. The results thus obtained and NMR spectrum studies rather support structure (III).     

Biochemical Studies on “Bakanae” Fungus. Part 55 Synthesis of Gibberellins

In order to clarify the structure of ring A of gibberellins, thirteen lactones of cyclohexan series, of which eight were new, were prepared to examine their infrared spectra. So far; the experiment is concerned, γ-lactones show the characteristic absorption band in the rang 1775~1782 cm^?1 in dioxane, while 5-ones in the range 1730/~1762 cm^?1. Since the absorptio band due to lactone carbonyl of gibberellins occurs at the range 1777~1786 cm^?1 in dioxane, the lactone ring of gibberellins seems to be γ.     

Biochemical Studies on “Bakanae” Fungus. Part 68. Synthesis of Substances related to Gibberellins

Mucor hiemalis endo-β-N-acetylglucosaminidase (Endo-M) was proved to act on complex type biantennary oligosaccharides of glycoproteins by using dansylated asparagine-linked and pyridylaminated oligosaccharides, as the substrate. The enzyme could act on both asialo- and sialo-biantennary oligosaccharides. This is the only endo-β-N-acetylglucosaminidase known to act on sialo glycans, though their activity for them was weak. The enzyme could liberate complex type biantennary oligosaccharides from native human asialotransferrin, which was ascertained by a combination of the pyridylaminated method and HPLC. The enzyme had substrate specificity for high-mannose type oligosaccharides different from those of the endo-β-N-acetylglucosaminidases of other microorganisms: ovalbumin glycopeptide-IV was a better substrate for Endo-M than glycopeptide-V. The enzyme could act on complex type triantennary oligosaccharides of dansylated glycopeptide prepared from calf fetuin. The enzyme had various novel specificities in regard to activities on complex type and high-mannose type oligosaccharides in glycoproteins.     

Biochemical Studies on “Bakanae” Fungus. Part 74. Synthesis of Substances Related to Gibberellins

Synthesis of the C-10 epimer of racemic desoxogibberic acid is described.     

Biochemical Studies on “Bakanae” Fungus. Part 65. Synthesis of Substances related to Gibberellins

Several gibbene dicarboxylic acids were relactonized to afford lactonic acids, gibberellin C and desoxygibberellin C. The β-configuration of the hydrogen atom at position 4b of gibberellic acid was supported.     

Biochemical Studies on “Bakanae” Fungus. Part XXXVI The Physiological Action of Gibberellin. VIII

The seventh leaf-sheaths of rice plants grown in solution and treated with gibberellin were analyzed to examine their changes in the activities of various enzymes during period of growth, in comparison with that of the control plants. Phosphatase, alkalipyrophosphatase, acetylesterase, maltase, β-glucosidase, α-galactosidase, β-galactosidase, amylase, urease, dipeptidase, ascorbic acid oxidase, and catalase activities were decreased in extracts of sheaths on a fresh weight basis by treatment with gibberellin. Activities of peroxidase and invertase were markedly increased.     

Biochemical Studies on “Bakanae” Fungus. Part 58–59. Synthesis of Substances related to Gibberellins

Synthesis of a new lactone of cyclohexane series, 3-methyl-cyclohexane-cis-diol-(2,5) -carboxylic acid lactone, is described. Spectroscopic properties of this and another lactone as well as two related esters are listed.     

Biochemical Studies on “Bakanae” Fungus. Part 70–71. Synthesis of Substances related to Gibberellins

Several gibbane-10-carboxylic acids and esters, including methyl (±)-desoxogibberate and methyl (±))-desoxoepigibberate, were synthesized.     

Comparative Biochemical Studies on α-Glucosidases

The substrate specificity of Schizosaccharomyces pombe α-glucosidase has been investigated.

The range of opt. pH was 4.0~4.4 and opt. temp. 45°C. The enzyme lost almost all the enzymatic activity at 55°C for 15 min. and the range of pH-stability was 3.2~6.8 at 30 °C for 20 hrs.

The enzyme was active especially on maltose in comparison with other α-glucosides. The rate of hydrolysis decreased in the following order: maltose, isomaltose, phenyl-α-glucoside, panose and turanose. Therefore, the substrate specificity of the enzyme was quite different from that of brewer’s yeast (Saccharomyces cerevisiae) α-glucosidase, though similar to that of mold α-glucosidase.     

Biochemical Studies on Buckwheat α-Glucosidase

The transglucosylation action of buckwheat α-glucosidase on soluble starch, maltose maltotriose and maltotetraose are described and discussed. The transglucosylation products of soluble starch were isolated by carbon-Celite column chromatography and by paper chromatography. Among the products were found follows: nigerose, maltose, kojibiose and isomaltose as disaccharides and 2-α-isomaltosylglucose, 2-α-nigerosylglucose, nigerotriose. 3-α-maltosylglucose and maltotriose as trisaccharides.

Furthermore, the existence of 6-α-nigerosylglucose, 4-α-kojibiosylglucose, panose, isopanose and 3-α-isomaItosylglucose was suspected. A new trisaccharide, 2-α-nigerosylglucose which was obtained in a crystalline form (monohydrate) melted at 186~188°C and gave [α]_D+ 178.3 (c = 0.6, in water).

These experimental results on the reaction products seem to indicate that the activated glucosyl group from the substrate (starch, in this case) is transferred to any position of C–2,3,4 or 6 of glucose released from the substrate and the same type of transglucosylation occurrs upon the non-reducing terminal of disaccharides just produced, which leads to the formation of various kinds of trisaccharide, tetrasaccharide etc. The synthesis of α-oligosaccharides from free glucose could not be detected by paper chromatography.     

Biochemical Studies on Bakanae Fungus. Part 60–62. Synthesis of Substances related to Gibberellins

A synthesis of a compound of gibberic acid type is described.