Seung-Suh Hong

Characterization and cDNA cloning of two glycine- and histidine-rich antimicrobial peptides from the roots of shepherd's purse, Capsella bursa-pastoris

Two novel antimicrobial peptides were isolated and characterized from the roots of shepherds purse, Capsella bursa-pastoris. These antimicrobial peptides, named shepherin I and shepherin II, consist of 28 and 38 amino acids, respectively, and are glycine- and histidine-rich peptides. Shepherin I and shepherin II have 67.9% and 65.8% (mol/mol) glycine, respectively, and 28.6% and 21.1% (mol/mol) histidine, respectively. Both shepherins have a Gly-Gly-His motif. These antimicrobial peptides exhibit antimicrobial activity against Gram-negative bacteria and fungi. Circular dichroism spectra of shepherin I and shepherin II showed that shepherin I and shepherin II in 50% trifluoroethanol have 66.7% and 75% random coils, respectively, without any α-helices. cDNA sequence analysis revealed that shepherin I and shepherin II are produced from a single polypeptide, designated shep-GRP, consisting of 120 amino acids; shep-GRP has five distinct domains, an amino-terminal putative signal peptide, a shepherin I, a linker dipeptide, a shepherin II and a carboxy-terminal peptide. Southern blot analysis indicates that the gene encoding shepherins belongs to a low-complexity gene family. Northern blot analysis revealed that transcripts of shep-GRP are present in roots but not in leaves and stems.

Effect of osmotic pressure on paclitaxel production in suspension cell cultures of Taxus chinensis

The effect of osmotic pressure on paclitaxel production was investigated in the suspension cell cultures of Taxus chinensis. Paclitaxel production was definitely influenced by the initial sucrose concentration and the highest production yield was achieved at the concentration of 60 g.l(-1) sucrose (300 mOsm.kg(-1)). High osmotic pressure conditions generated by non-metabolic sugar (mannitol and sorbitol) also enhanced paclitaxel production by about two-fold. Kinetic studies revealed that high initial osmotic pressure enhanced paclitaxel production and that high concentration of sucrose was effective for sustaining secondary metabolism after induction of paclitaxel biosynthesis. Stoichiometric analysis with different combinations of sucrose and mannitol confirmed that osmotic pressure was the more important factor for enhancing paclitaxel metabolism. The addition of non-sugar osmotic agent, PEG also enhanced paclitaxel production. In this paper, we showed that high osmotic pressure led to increases in paclitaxel production and proposed that regulation of osmotic pressure may be useful in controlling paclitaxel production.

Mass Production of Paclitaxel by Plant Cell Culture

Samyang Genex succeeded in commercialization of anticancer agent-paclitaxel by plant cell culture technology. The core technology of Samyang Genex relating paclitaxel production includes cell line development, cell line preservation, cell culture, scale-up technology, and purification technology. On the basis of the research, Samyang Genex built the factory operated by CGMP (current good manufacturing practice). The paclitaxel-Genexol-is commercially available in Korea, and it will be launched to world market including USA after approval of US FDA.

Enhancement of paclitaxel production by temperature shift in suspension culture of Taxus chinensis

Effect of temperature shift during culture period on cell growth and paclitaxel was investigated to optimize paclitaxel production in suspension culture of Taxus chinensis. Cell growth showed the optimum at 24 degrees C while paclitaxel synthesis showed the maximum at 29 degrees C. To minimize the inhibitory effect of higher temperature on cell growth, temperature was shifted after a certain period of culture time at 24 degrees C. Paclitaxel synthesis in plant cell culture increased dramatically during day 14 to day 21 regardless of treatment, reaching the maximum production of 137.5 mg paclitaxel/L. When the temperature was maintained at 29 degrees C after day 21, the specific productivity of paclitaxel was sustained for prolonged period of 42 days. The possible relationship between temperature and paclitaxel synthetic pathway was also suggested.

A simple method for the purification of an antimicrobial peptide in recombinant Escherichia coli.

A magainin derivative, designated MSI-344, was produced in Escherichia coli as fusion protein, by utilizing a truncated amidophsphoribosyltransferase of E. coli as a fusion partner. Bacterial cells transformed with the gene encoding the fusion protein were grown to a high cell density and induced with isopropyl-1-thio-b-D-galatoside (IPTG) to initiate product expression. The fusion protein was accumulated into cytoplasmic inclusion body and recombinant MSI-344 was released from the fusion partner by hydroxylamine treatment. Following cleavage of the fusion protein with hydroxylamine, the released MSI-344 was purified to homogeneity by cationic exchange chromatography. The final purity was at least 95% by reversed-phase high performance liquid chromatography (RP-HPLC). Purified recombinant MSI-344 was found to be indistinguishable from the synthetic peptide determined by amino acid sequences and antimicrobial activity assay.

Optimization of the hydroxylamine cleavage of an expressed fusion protein to produce a recombinant antimicrobial peptide

Hydroxylamine was used to cleave the Asn-Gly peptide bond between the fusion partner and the antimicrobial peptide of interest, a magainin derivative (MSI-344). The efficiency of reaction depended on the hydroxylamine concentration, denaturant, pH, and the fused protein concentration. The optimal cleavage solution consisted of guanidine ⋅ HCl as the denaturant, pH 8.1, and 6.7 mg ml−1 of fused MSI-344. This optimized cleavage solution resulted in a high yield (∼95% ) of MSI-344 from a cultivation of E. coli. This result suggests potential applications for using hydroxylamine to cleave basic peptides produced from fusion proteins.

Enhanced production of paclitaxel by semi-continuous batch process (SCBP) in suspension culture of Taxus chinensis

Abstract Semi-continuous batch process (SCBP) was developed for the production of paclitaxel from suspension culture of Taxus chinensis . Cell ages did not affect the specific production of paclitaxel, and it was possible to use the cells at day 21 as an inoculum for another cycle of production batch. Using SCBP, paclitaxel productions at day 42 were increased from 46.9 at cycle 1 to 85.5 mg l −1 at cycle 4, but decreased at cycle 5 and 6. It was elucidated that the enhanced production of paclitaxel by SCBP was mainly due to the pre-treatment of silver nitrate.

A method for mass production of taxol by semi-continuous culture

The present invention relates to a method for mass production of taxol by semi-continuous culture of Taxus genus plant with a high yield. According to the present invention, taxol can be prepared with a high yield, by employing semi-continuous culture of Taxus genus plant cell, which comprises: (i) inoculating Taxus genus plant cell on a medium containing 1 to 10 % (w/v) sugar, and incubating it; and, (ii) transferring 1/10 to 1/2 volume of the culture obtained in the step (i) to a fresh medium and repeating the step (i), adding 1 to 10 % (w/v) sugar to the remnant culture and incubating to the time of maximum production of taxol.

Recovery of extracellular paclitaxel from suspension culture of Taxus chinensis by adding inorganic salts

A new and simple method was developed to recover paclitaxel from the extracellular culture medium of Taxus chinensis. More than 80% of paclitaxel in the medium was obtained by adding 7.8 mM MgSO4 or greater and then centrifuging. The concentration of baccatin III in the supernatant did not change after MgSO4 treatment while paclitaxel was precipitated in the pellet. This method was used to recover paclitaxel without baccatin III from the extracellular culture medium of Taxus species.

Removal of endotoxin in the purification of histone H1.5 from Escherichia coli

Triton X-114 and cation-exchange chromatography, SP-Sepharose FF, removed endotoxins from solutions containing recombinant histone H1.5. Dissociated endotoxins were removed but fractions containing histone H1.5 were enhanced in the elution step. The final concentration of endotoxins, measured by a limulus amoebocyte lysate (LAL) assay, was below 0.05 EU mg−1 histone H1.5. The recovery of protein was above 95%.