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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal Basic Information
Journal DOI :
Korean Society for Biotechnology and Bioengineering
Editor in Chief :
Volume & Issues
Volume 9, Issue 5 - Dec 1994
Volume 9, Issue 4 - Oct 1994
Volume 9, Issue 3 - Sep 1994
Volume 9, Issue 2 - Jun 1994
Volume 9, Issue 1 - Mar 1994
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Mechanism of Dextran Synthesis by Dextransucrase
KSBB Journal, volume 9, issue 1, 1994, Pages 1~7
A qualitative study was made on the mechanism of dextran synthesis by dextransucrase. Enzymatic synthesis of dextran was experimentally studied with initial sucrose concentration from 50g/
. The molecular weight distribution of synthesized dextran was measured by using on-line gel Permeation chromatographic system Sucrose was observed not to work as a primer within the range of concentration tested. At the initial sucrose concentration of 50g/
, dextran with molecular weight of medium range (
) was synthesized due to the mass transfer limitation of sucrose. The amount of the dextran of medium range decreased with the initial sucrose concentration. Dextran was likely to be synthesized by radical chain polymerization mechanism since the dextran of medium range was not produced at higher sucrose concentrations.
Optimization of Environmental Conditions for Hirudin Production from Recombinant Saccharomyces cerevisiae
KSBB Journal, volume 9, issue 1, 1994, Pages 8~15
The research has been carried out to optimize a recombinant S. cerevisine fermentation process for the production of an anticoagulant hirudin. The structural gene coding for hirudin was combined with the GAL10 promoter for controlled expression, the MFal signal sequence for hirudin secretion, and the GAL7 terminator for transcriptional termination. Growth medium composition and environmental conditions were optimized for maximizing cell growth and final hirudin concentration. The optimized conditions included yeast extract 40g/
, casamino acid 5g/
, g1ucose 20g/
, galactose 30g/
, DO 50% and temperature
. These conditions yielded the specific cell growth rate of
, the final cell density of 30g cell/
and the final hirudin concentration of 64mg/
in the batch fermentation with a 2.5
Development and Characterization of Sporulation Mutants for Overexpression of Recombinant Protein of Bacillus subtilis
KSBB Journal, volume 9, issue 1, 1994, Pages 16~25
Sporulation mutants of Bacillus subtilis were developed for overproduction of heterologous proteins. The strains spoOJ spoIIG, and spoOJ spoIIG double mutant were constructed from two pretense-delfted mutant (DB104). The vector containing aprE gene was integrated in the chromosome of each strain, then the morphology of each strain was observed by TEM (trasmission electron microscopy). The morphology of spoOJ mutant and spoIIG mutant coincides with the description of the previous reports, respectively. The sporulating cells of spoOJ SpoIIG double mutation resemble spoIIG mutant more similarly, but with a little rougher cell wall membrane. The spoOJ mutation in B. subtilis gives negative effect on aprE activity with only a decreased sporulation frequency. On the contrary spoIIG mutation increases the aprE activity twice with an undetectable sporulation frequency. In the case of spoOJ and spolIG, i. e. double mutation, the effect of spoOJ on aprE activity seems to be relieved and the double mutant shows more or less the same aprE activity compared to spoIIG mutant.
Effect of Exogenous Hormones on Anthocyanin Accumulation and Phenylalaine Ammonia-lyase and Chalcone-synthase Activity in the Hairy Root Cultures of Raphanus sativus cv. Chungpihongsim
KSBB Journal, volume 9, issue 1, 1994, Pages 26~34
When effects of exogenous hormone on hairy root cultures of Raphanus sativs cv. Chungpihongsim examined, the highest anthocyanin synthesis and disorganization were observed when 2, 4-D was supplemented to the culture medium Cytokinins showed early weak induction after transfer and ABA showed inhibitory effect and GA3 showed no effects in anthocyanin synthesis. Hormones except for 2, 4-D in 1 mg/
concentration did not induce disorganization of hairy root and retarded growth of hairy root. Time-course changes in anthocyanin synthesis, phenylalanine ammonia-lyase activity and chalcone synthase activity were examined in culture condition contalning 2, 4-D and kinetin. In a medium containing 2, 4-D, anthocyanin synthesis began to increase on the 9th day and reaching maxima on the 18th day after transfer. Maximum peak of PAL activity appeared on the 3-9th day and another minor peak appeared on the 18th day. CHS activity increased from 9th day, reaching maximum on the 18th day and remained at a relatively high level for culture period. In a medium containing kinetin, anthocyanin synthesis increased temporarily on the 6-9th days, early days after transfer and maintained at a low level for remaining culture period. Peak of PAL activity appeared on the 6th day and CHS activity increased from the 6th days, reaching maxima about 18th day and remained at a relatively high level. In particular, addition of kinetin after preculture in hormone free medium for 2 weeks which was thought of wound healing period showed no effects in anthocyanin synthesis. This results showed that stimulation of anthocyanin synthesis by 2, 4-D and kinetin was meaningfully connected with changes of PAL, CHS activity, and then suggested rate-limiting role of CHS on anthocyanin synthesis in that there is close correlation between anthocyanin synthesis and changes of CHS activity in time-course. Besides, it is considered that cytoklnins involving kinetin stimulated anthocyanin synthesis be due to "wound response" by cutting of young roots, and that difference in time-course peak and PAL, CHS activities expressed by 2, 4-D and kinetin result from occurrence of isozyme which have different regulatory mechanism.mechanism.
Separation and Purification of Fructo-oligosaccharides by an Ion-Exchange Resin Column
KSBB Journal, volume 9, issue 1, 1994, Pages 35~39
Separation of pure fructo-oligosaccharides from the mixed solution of glucose, sucrose and fructo-oligosaccharides was studied using a cationic ion-exchange resin column. Optimum separation conditions, i.e., temperature, feeding rate and the ratio of column vs. diameter were evaluated, which were found to be
and 30, respectively. At the optimized separation conditions, high-purity fructo-oligosaccharides up to 96% were obtained and the total recovery yield was about 66% after four cycles. After the chromatographic separation, purification to remove the salts and color in pure fructo-oligosaccharides solution was successfully conducted using the mixed-bed of cationic and anionic ionexchange resin columns.
Mathematical Model for the Production of High-purity Fructo-oligosaccharides by the Mixed-enzyme System of Fructosyltransferase and Glucose Oxidase
KSBB Journal, volume 9, issue 1, 1994, Pages 40~47
A simplified mathematical model for the production of high-purity fructo-oligosaccharides by the mixed-enzyme system of fructosyl transferees and glucose oxidase was proposed and compared with the experimental results. The kinetic parameters including
were estimated at
, in which
, values decreased and
values increased compared with those of fructosyl transferees alone. The kinetics of the mixed-enzyme system was successfully described in the form of Michaelis-Menten equations. At the reasonable sucrose concentrations tested, the simulated sugar profiles were of good agreement with the experimental ones.
Kinetics of Converting Single Chain Urokinase Type Plasminogen Activator into Two Chain Plasminogen Activator in Cultivating HEK Cells with Low Serum Containing Medium
KSBB Journal, volume 9, issue 1, 1994, Pages 48~54
A modified amidolytic assay and a fibrin plate method were used to accurately measure the concentration of single chain urokinase type plasminogen activator (scu-PA) and two-chain urokinase type plasminogen activator (tc-PA) in the spent media.
(viable cells/ml) of maximum cell density and 1670(IU/ml) of scu-PA concentration were obtained in 1% serum containing medium. The overall conversion ratio from scu-PA to tc-PA was less than 10%. In the results of batch cultivation in a spinner vessel,
of maximum cell density and 1560(IU/ml) of scu-PA concentration was observed. The maximum scu-PA concentration and specific scu-PA Productivity were obtained in 1760(IU/ml) and
, respectively, from perfusion cultivation. The conveysion ratios from batch, fed-batch and perfusion cultivations were less than 12%, which means that about 90% of scu-PA secreted from the cells can be maintained during the cultivations.
Novel Purification and Characterization of Glucose oxidase from Aspergillus niger
KSBB Journal, volume 9, issue 1, 1994, Pages 55~62
Glucose oxidase(EC 188.8.131.52) was purified to electrophoretic homogeneity from Aspergillus niger by a combination of ammonium sulfate fractionation, ion exchange chromatography, and ultrafiltration. Two active fractions A and B, of glucose oxidase were obtained from the hydrophobic chromatography on phenyl sepharose CL-4B. The enzyme A and B were glycoproteins with the same denatured molecular weight of 78, 000 and had specific activities of 2, 191 and 1, 273-units/mg proteins, respectively. But the two enzymes showed differences in native molecular weight that was measured by HPLC gel filteration, maximum absorbtion wavelength and isoelectric point. The enzyme A oxidized
-D-glucose only and was resistant to sodium dodecyl sulfate. Activity optimum was found at
and pH 3.5. Also the enzyme A was inhibited greatly by
(10mM). The results of chemical modification experiments suggested that cysteine and cystine residues might be involved in the active site of the enzyme A.
Solvent Effect on Restriction Endonuclease : Alteration of Specificity of Restriction Endonuclease PvuII in Hydrophobic Solution
KSBB Journal, volume 9, issue 1, 1994, Pages 63~71
During the last decade enzyme reaction in organic solvent has been studied to show that specificity in buffer is different from that in organic solvent. The specificity of restriction enzyme was effected by various factors such as ionic strength, salt organic solvent and temperature. In this study, restriction enzyme PvuII which is used most frequently in genetic engineering and the substrate was vector pGEM3 whose sequence was already known were used. As a result the recognition sequence site was changed in the presence of organic solvents whose Log P are -1.5∼0. Their specificities were contrast with activities were contrasted. Specificities were not changed in organic solvent easily in inactivating enzyme. We think that the enzyme recognition site was not changed randomly but by preferential order. A recombinant vector which does not contain typical cleavage site CAG↓CTG was cleaved in 20% ethanol solution. This result might show that restriction enzyme could be used to cleave at unusual sites by changing the reaction conditions.
A Mathematical Model for the Whole Ripening Process of Cheddar Cheese
KSBB Journal, volume 9, issue 1, 1994, Pages 72~84
A model to explain the observed kinetics in a whole process of Cheddar-cheese ripening has been developed. It includes growth and lysis of cells in the cheese matrix, cell-wall bound protelnases and intracellular dipeptidases that are released into cheese upon cell lysis, and the production of dipeptides and amino acids from casein in cheese. Model simulations have been conducted to figure out the crucial factors in the process of the cheese ripening. The influential factors have been found to be the cell numbers and the dipeptidase activity at the beginning of the cheese ripening, and the cell-lysis rate of cheese starters. The simulation results have also suggested the use of a mixed culture as well as the experimental screening for a more suitable organism as a cheese starter hence, the model shows how to accelerate the cheese ripening.
Gellan-type Microbial Polysaccharide Production in Continuous Fermentation
KSBB Journal, volume 9, issue 1, 1994, Pages 85~90
The Gellan-type polysaccharide produced by Pseudomonas elodea(ATCC 31461) is one of the new heteropolysaccharides, having useful properties as gelling, suspending, stabilizing, emulsifying and binding agents in aqueous systems. Medium compositions for growth stage and production stage are improved. The problems of low cell concentration and poor productivity in highly viscous fermentation were attributed to inadequate mixing accompanied by insufficient oxygen transfer. During continuous culture, cell growth and polysaccharide production were greatly affected by the apparent viscosity, and they showed oscillation behavior, i.e. as the product concentration increases, cell concentration decreases. With improved culture conditions, the productivity of continuous culture increased up to 0.6g/
/hr(6-fold that of batch culture ) at dilution rate, D=