• Korean Journal of Food Science and Technology
• /
• v.11 no.3
• /
• pp.188-191
• /
• 1979

The heat decomposition rate of guanosine-5'-monophosphate was investigated in pH range from 5.52 to 7.00, and 0.1 of the ionic strength. The result showed that the rate was a first-order reaction and the rate of guanosine-5'-monophosphate loss was maximum near $pKa_2$. The loss of guanosine-5'-monophosphate was temperature dependent and followed to the Arrhenius equation in the temperature region from $93^{\circ}C$ to $108^{\circ}C$. The rate constant as function of temperature ($93^{\circ}C$ to $108^{\circ}C$) and neutral pH($pKa_2$, 6.0, to 7.0) was correlated by least-square fit of the experimental data; $$K=4.19{\times}10^{26}\;{\exp}\;[-1.3(pH+E/RT)]$$

• The Korean Journal of Mycology
• /
• v.12 no.4
• /
• pp.141-152
• /
• 1984

Aspergillus niger van Tieghem was cultured by the method of synchronous and submerged culture. Throughout the culture, sporulation was occured. Highly phosphorylated nucleotides in sporulating mycelia were detected to assure whether the eucaryotic Aspergillus niger produce these substances or not during the differentiation. Phosphorylated nucleotides were extracted from the conidiophore, bearing mycelia and spore forming body, these nucleotides were identified by TLC with P.E.I. cellulose. Guanosine tetraphosphate was found in both phialide forming mycelia and spore forming body. The contents of free amino acids were assayed and its level was found to increase at early stage of sporulation. The effects of 8-azaguanine examined, it was found to prevent spore formation and to made abnormal structure. The effects of inosinic monophosphate and guanosine monophosphate on spore formation were examined, spore formation was enhanced by these nucleotides.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.12 no.1
• /
• pp.1-6
• /
• 1983

Nucleobases and nucleosides in Panax and Acanthopanax genus were determined by high-performance liquid chromatography. Chromatography was performed on a reversed-phase system with ${\mu}$ Bondapak $C_{18}$ column using phosphate buffer and 80% methanol gradient. Content of each nucleobase in two genera was about 0-2mg/100g. Panax was contained guanosine and/or adenosine ca. 15-22mg/100g;and Acanthopanax guanosine ca. 3-8mg/100g and adenosine ca. 2-7mg/100g. Considerable amounts of cytidine, uridine, inosine, and thymidine were also detected in two genera.

• The Korean Journal of Mycology
• /
• v.12 no.3
• /
• pp.111-116
• /
• 1984

Ribonucleic acid contents and mononucleotides distribution from the mycelium and fruit bodies of Ganoderma lucidum were studied. P.E.I. cellulose TLC and HPLC were applied in this study. The obtained results are as follows; The levels of ribonucleic acids from the young basidiocarp mycelium were higher than those of mature basidiocarp. Guanosine 5'-monophosphate and xanthosine 5'-monophosphate were found in both young basidiocarp mycelium and mature basidiocarp. The levels of guanosine 5'-monophosphate and xanthosine 5'-monophosphate from the young basidiocarp were higher than those of the mature basidiocarp. However, inosine 5'-mono­phosphate was not detected.

• Natural Product Sciences
• /
• v.18 no.3
• /
• pp.171-176
• /
• 2012

We previously isolated cordycepin, guanosine and tryptophan from Cordyceps militaris as antiadipogenic constituents. For the quality control of C. militaris for anti-adipogenic activity, simultaneous analytical method using high-performance liquid chromatography (HPLC)-diode array detection (DAD) was developed and validated. Quantitation of these compounds in various Cordyceps samples from different sources and various extraction methods were conducted using developed method. Our study shows that natural Cordyceps and host insect possess higher content than cultured ones and fruiting bodies, respectively. The content of cordycepin showed great difference in different C. militaris samples whereas trytophan content was similar in tested samples. Addition of water to extraction solvent greatly increased the yield of guanosine and tryptophan. High temperature and longer extraction time increased yield of guanosine, whereas the content of trytophan was decreased in high temperature during extraction with water. Extraction using ultrasonic apparatus slightly increased extraction efficiency. Cordycepin, however, has little variation in different extraction method tested. Strong anti-adipogenic activity was observed in the samples that contain all the three constituents. Taken together, quantitation of these compounds using developed analytical method might provide basic requirement for the anti-adipogenic activity of C. militaris.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.6
• /
• pp.731-733
• /
• 1999

• Microbiology and Biotechnology Letters
• /
• v.9 no.1
• /
• pp.1-6
• /
• 1981

Crystallization conditions of disodium guanosine-5'-monophosphate (5'-GMP. 2Na) were studied. The solubility of 5'-GMP. 2Na was decreased by addition of methanol and the optimum condition was as follows. The crystallization was carried out at 45$^{\circ}C$ with agitation rate of 160-200 rpm., which is Reynold's No. of 25, 000-32, 000. When concentration of methanol was 7.5%~10.0%, the 5'-GMP. 2Na was easily crystallized by addition of crystal seed.

• Korean Journal of Microbiology
• /
• v.20 no.4
• /
• pp.201-209
• /
• 1982

An enzyme, named GTP cyclohydorlase, that catalizes the hydrolytic removal of carbon No.S of GTP has been partially purified from extracts of Pseudomonas putida (IAM 1506). The enzyme exists in two molecuar weight forms : a high molecular weight form (150,000) and a low molecular weight from (40,000). The high molecular weight form has been purified 25-fold. Some of the properties of the enzyme are as follows : It functions optimally at pH8.0, and at $52^{\circ}C$. The Km value for GTP is $20{\mu}M$. Divalent cations $(Cd^{2+}\;and\;Hg^{2+})$ 2+/) at a concentration of 5mM inhibit completely the enzyme activity. No metal ion including $Mg^{2+}$ is needed for the catalysis. The enzyme is heat labile ; its half at $57^{\circ}C$ is 1.5 min. Of a number of nucleotides tested, only GDP was used to any extent as substrbte in place of GTP. One of the products of the enzyme is determined to be a dihydro-neopterin compound.

• Journal of Microbiology
• /
• v.34 no.1
• /
• pp.82-89
• /
• 1996

Purine nucleoside phosphorylase (PNP) was purified in Micrococcus luteus (M. luteus) using streptomycin sulfate and amomonium sulfate fractionation, three times by a Sephadex G-100 gel filtration and a DEAE-Sephadex A-50 ion exchange chromatography. The enzyme was purified 72 folds with a 11% recovery and showed a single band in a nondenaturing gel electrophoresis. The M. W. of PNP turned out to be 1.35 * 10$^{5}$ delton in G-150 gel filtration chromatography. The stability of the enzyme was increased by treatment with both substrates, MgCI$_{2}$ or CaCI$_{2}$, but not significantly kcal/mol. M. luteus PNP catalyzed the phosphorolysis of inosine, deoxyinosine, guanosine and deoxyguanosine with the Km value of 1.5 * 10$^{-3}$ M, 3.0 * 10$^{-3}$ M, 5.0 * 10$^{-4}$ M, respectively. The enzyme was reacted with adenosine, 1-methylnosine and 1-methylguanosine as substrates, which were shown to be poor substrates for mammalian enzyme.

• Journal of Microbiology
• /
• v.35 no.1
• /
• pp.15-20
• /
• 1997

Kinetic studies were done to elucidate the reaction mechanism of purine nucleoside phosphorylase (PNP) in Micrococcus Luteus. PNP catalyzes the reversible phosphorolysis of ribonucleosides to their respective base. The effect of alternative competing substrates suggested that a single enzyme was involved in binding to the active site for all purine nucleosides, inosine, deoxyiosine, guanosine, deoxyguanosine, adenosine and deoxyadenosine. Affinity studies showed that pentose moiety reduced the binding capacity and methylation of ring N-1 of inosine and guanosine had little effect on binding to bacterial enzyme, whereas these compounds did not bind to the mammalian enzymes. The initial velocity and product inhibition studies demonstrated that the predominant mechanism of reaction was an ordered bi, bi reaction. The nucleoside bound to the enzyme first, followed by phosphate. Ribose 1-phosphate was the first product to leave, followed by base.