• Journal of Pharmaceutical Investigation
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• v.41 no.2
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• pp.91-94
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• 2011

The purpose of this study was to investigate the effect of peptide charge on the interaction between peptide and poly(D,L-lactide-co-glycolide) (PLGA) for evaluating mechanism of acylated peptide formation in PLGA matrix. As a model peptide, octreotide, a synthetic somatostatin analogue and active ingredient of commercial PLGA product, was used. The disulfide group of octreotide was reduced with dithiothreitol and the sulfhydryl groups were modified with N-${\beta}$-maleimidopropionic acid (BMPA) to neutralize octreotide with positive charge in physiological conditions. The BMPA-conjugated octreotide was identified by measuring the molecular mass with liquid chromatography-mass spectrometry. In the interaction study with PLGA, native octreotide showed initial adsorption to PLGA and substantial production of acylated peptides (56% of overall peptide), whereas BMPA-conjugated octreotide showed minimal adsorption to PLGA and no acylation products for 42 days. Consequently, the neutralization of octreotide completely inhibited the peptide acylation by preventing interaction of peptide with PLGA. In conclusion, this study demonstrates that the initial polymer interaction of peptide is important step for peptide acylation in PLGA matrix and suggests the modulation of peptide charge as strategy for inhibiting the formation of acylated peptide impurities.

• Polymer(Korea)
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• v.33 no.3
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• pp.219-223
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• 2009

The nanofibers fabricated by using an electrohydrodynamic process has been used as various applications, such as nano-device, filtering system, protective clothes, wound dressing, and drug delivery system (DDS). Of these applications, the DDS should be needed to minimize side effects of drugs, maximize the properties of medicine, and efficiently deliver the required amount of drugs to the diseased area. In this paper, by using the electro spinning process, which is one of electrohydrodynamic processes, two different types, polycarprolactone and poly(ethylene oxide)/Rhodamine B, of electrospun mats were fabricated layer by layer and the release behavior of Rhodamine B was characterized with time. In addition, to show the feasibility of DDS of this type, we tested release behavior of a peptide of the nanofiber system, a PCL/(Peptide+PEO)/PCL nanofiber mat. The released peptide did not loss biological activities. From these results, we believe that the layered nanofiber mat as a DDS has enough function of a new drug delivery system.

• IMMUNE NETWORK
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• v.22 no.5
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• pp.42.1-42.20
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• 2022

Vaccination with tumor peptide epitopes associated with MHC class I molecules is an attractive approach directed at inducing tumor-specific CTLs. However, challenges remain in improving the therapeutic efficacy of peptide epitope vaccines, including the low immunogenicity of peptide epitopes and insufficient stimulation of innate immune components in vivo. To overcome this, we aimed to develop and test an innovative strategy that elicits potent CTL responses against tumor epitopes. The essential feature of this strategy is vaccination using tumor epitope-loaded nanoparticles (NPs) in combination with polyinosinic-polycytidylic acid (poly-IC) and anti-PD1 mAb. Carboxylated NPs were prepared using poly(lactic-co-glycolic acid) and poly(ethylene/maleic anhydride), covalently conjugated with anti-H-2K^b mAbs, and then attached to H-2K^b molecules isolated from the tumor mass (H-2^b). Native peptides associated with the H-2K^b molecules of H-2K^b-attached NPs were exchanged with tumor peptide epitopes. Tumor peptide epitope-loaded NPs efficiently induced tumor-specific CTLs when used to immunize tumor-bearing mice as well as normal mice. This activity of the NPs significantly was increased when co-administered with poly-IC. Accordingly, the NPs exerted significant anti-tumor effects in mice implanted with EG7-OVA thymoma or B16-F10 melanoma, and the anti-tumor activity of the NPs was significantly increased when applied in combination with poly-IC. The most potent anti-tumor activity was observed when the NPs were co-administered with both poly-IC and anti-PD1 mAb. Immunization with tumor epitope-loaded NPs in combination with poly-IC and anti-PD1 mAb in tumor-bearing mice can be a powerful means to induce tumor-specific CTLs with therapeutic anti-tumor activity.

• International Journal of Industrial Entomology and Biomaterials
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• v.20 no.2
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• pp.87-91
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• 2010

Silk fibroin model peptide, alanine pentamer was synthesized through solid-phase method and modified with poly(ethylene glycol). Nuclear magnetic resonance spectrometry and Fourier-transform infrared spectroscopy showed the conformation of alanine pentamer, $\beta$-sheet structure and random coil conformation were not changed with PEGylation. Differential scanning calorimetry showed that relatively strong exothermic peak around $180^{\circ}C$ by PEGylation. No cytotoxicity of PEGylated pentamer was observed by L929 cell proliferation test.

• Journal of Pharmaceutical Investigation
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• v.40 no.4
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• pp.251-254
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• 2010

The formation of acylated peptide impurities in poly(lactide-co-glycolide) (PLGA) formulations is one of the major challenges to the development of successful sustained-release product. Octreotide, synthetic analogue of somatostatin, has been identified to be acylated in PLGA microsphere formulations. The purpose of this study was to investigate the pH effect on the formation of acylated octreotides by PLGA. In the incubation with PLGA in 0.1 M phosphate buffer at pH 7.4, approximately 98% of octreotide adsorbed to PLGA through 14 days and 66.3% of acylated octreotides were produced after 42 days, whereas the interaction of octreotide with PLGA was significantly inhibited in the incubation at pH 4, in which the acylated octreotides were observed to be 9.2% after 42 days. In the interaction study at pH 4.1-7.4, the production of acylated octreotides was demonstrated to be dependent on environmental pH. Below pH 5.0, the acylation of octreotide was significantly inhibited. This study indicates that the pH is the major factor for the formation of acylated octreotide in PLGA formulations.

• Journal of Pharmaceutical Investigation
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• v.23 no.3
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• pp.31-40
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• 1993

It is essential to clone the peptide transporter in order to obtain better understanding of its molecular structure, regulation, and substrate specificity. Characteristics of an endogenous peptide transporter in oocytes were studied along with expression of an exogenous proton/peptide cotransporter from rabbit intestine. And further efforts toward cloning the transporter were performed. The presence of an endogenous peptide transporter was detected in Xenopus laevis oocytes by measuring the uptake of $0.25\;{\mu}M\;(10\;{\mu}Ci/ml)\;[^3H]-glycylsarcosine$ (Gly-Sar) at pH 5.5 with or without inhibitors. Uptake of Gly-Sar in oocytes was significantly inhibited by 25 mM Ala-Ala, Gly-Gly, and Gly-Sar (p<0.05), but not by 2.5 mM of Glu-Glu, Ala-Ala, Gly-Gly, Gly-Sar and 25 mM glycine and sarcosine. This result suggests that a selective transporter is involved in the endogenous uptake of dipeptides. Collagenase treatment of oocytes used to strip oocytes from ovarian follicles did not affect the Gly-Sar uptake. Changing pH from 5.5 to 7.5 did not affect the Gly-Sar uptake significantly, suggesting no dependence of the endogenous transporter on a transmembrane proton gradient. An exogenous $H^+/peptide$ cotransporter was expressed after microinjection of polyadenylated messenger ribonucleic acid $[poly\;(A)^+-mRNA]$ obtained from rabbit small intestine. The Gly-Sar uptake in mRNA-injected oocytes was 9 times higher than that in water-injected oocytes. Thus, frog oocytes can be utilized for expression cloning of the genes encoding intestinal $H^+/peptide$ cotransporters. Using the technique size fractionation of mRNA was sucessfully obtained.

• Journal of Pharmaceutical Investigation
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• v.34 no.2
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• pp.101-106
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• 2004

This work aims at examining the cellular uptake behavior of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles derivatized with a protein transduction domain (PTD) using HeLa cells. For this purpose, $Tat_{49-57}$ peptide derived from transcriptional activation (Tat) protein of HIV type-1 was covalently conjugated to the terminal end of PLGA. Nanoparticles were ten prepared with the $Tat_{49-57}-PLGA$ conjugates by a spontaneous phase inversion method. The prepared particles had a mean diameter of ca. 84 nm, as measured by dynamic light scattering. The interaction of the Tat-PLGA nanoparticles with cells was examined by using confocal laser scanning microscopy. It was found tat Tat-PLGA nanoparticles incubated with HeLa cells could efficiently translocate into cytoplasm, while plain PLGA nanoparticles showed negligible cellular uptake. In addition, even at $4^{\circ}C$ or in the presence of sodium azide significant cellular internalization of Tat-PLGA nanoparticles was still observed. These results indicate that a non-endocytotic translocation mechanism might be involved in the cellular uptake of Tat-PLGA nanoparticles.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.88-89
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• 2003

A series of novel spinning acrylic polymer containing silk protein were synthesized by copolymerization of acrylonitrile (AN) and silk fibroin peptide (SFP) modified by acryloyl chloride (AC) with vinyl groups. The viscosity values of these copolymers showed that the copolymers have good spinnability, which are synthesized under the condition of putting a micro amount of metal ions into synthesizing solvent. The fiber based on the poly (AN-co-SFP) was prepared and characterized by SEM, FTIR measurement of its shell and core flakes, and moisture absorption. The fiber appeared a smooth surface and could be assumed to have excellent adhesive between SFP and PAN. Furthermore, these fibers showed a shell-core structure and excellent moisture absorption.

• Journal of Microbiology and Biotechnology
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• v.16 no.12
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• pp.1935-1939
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• 2006

The gene encoding the extracellular medium-chain-length poly(3-hydroxyalkanoate) (MCL-PHA) depolymerase of Pseudomonas luteola Ml3-4, $phaZ_{plu}$, was cloned and analyzed. It was found to be 849 bp, with a deduced protein of 282 amino acids, and was revealed to have a typical leader peptide at its N terminus. The amino acid sequence of $PhaZ_{plu}$ revealed relatively low identity (69 to 72%) with those of other Pseudomonas MCL-PHA depolymerases. In comparison with the amino acid sequences of all available MCL-PHA depolymerases, the depolymerase was found to consist of three domains in sequential order; signal peptide, an N-terminal substrate binding domain, and a catalytic domain, indicating that $PhaZ_{plu}$ belongs to the type IV depolymerases family. The enzyme also contained Asn as an oxyanion hole amino acid.

• Journal of the Korean Society of Industry Convergence
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• v.2 no.1
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• pp.77-83
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• 1999

Grown in the secondary broth of production media, the strain Streptomyces albulus has increased more the production of its metabolite ${\varepsilon}$-poly-L-lysine, one of poly(amino acid)s used as disinfecting food additives, than the strain in the primary culture of growth nutrients. Having the strain removed, the large concentrate obtained by ultrafiltrating the secondary culture broth. The concentrated production broth exchanged into followed by detecting in UV flowcell at 220nm the peptide bond of the components eluting the adsorbed proteins and polylysine with NaCl salt of gradient concentration, and has separated into five components. Among them the component in the fourth peak fraction has proved to be the pure ${\varepsilon}$-poly-L-lysine after the portion being hydrolyzed the fraction with HCl into amino acid followed by being the composing amino acid analysis.