• 생명과학회지
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• 제30권5호
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• pp.420-427
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• 2020

Repebody는 비면역 글로블린 인공 항체로 저렴하고 빠르게 생산 가능한 맞춤형 항체이다. 그러나 의료용 repebody의 생산은 저수율 및 복잡한 정제 공정으로 인해 여전히 어려움을 겪고 있다. Pseudomonas fluorescens의 ABC transporter를 사용한다면 생산 공정을 간소화하고 비용을 줄일 수는 있지만 repebody는 양전하를 띠어 분비 효율이 낮다. 따라서 등전점(pI)이 높은 repebody의 등전점을 낮추어 음전하를 띄도록 해야 한다. 이것을 위해 repebody의 N 말단과 C 말단에 연속된 아스파탐산을 붙여 보았지만 분비가 증가하지 않았다. 다른 방법으로 ABC transporter를 통한 repebody 분비 효율을 높이기 위해 repebody의 항원 결합 부위의 반대쪽에 존재하는 열다섯 개의 양전하 아미노산을 아스파탐산으로 변환하여 repebody 표면이 강한 음전하를 띠도록 하였다. 그 결과, 기존 repebody의 발현 단백질 당 분비효율은 21.2%였으나 변형한 과음전하 repebody의 분비효율은 58.5%로 향상되었다. 결론적으로 과음전하를 통해 만들어진 repebody는 P. fluorescens에 의해 세포 바깥에 분비 생산할 수 있었다.

• 대한방사성의약품학회지
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• 제5권2호
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• pp.83-88
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• 2019

In order to understand the in vivo biodistribution of repebody protein (RB), an efficient and simple radiolabeling method for the protein is needed. We demonstrate a detailed protocol for the radiosynthesis of an ¹¹¹In radiolabeled tetrazine prosthetic group and its application to the efficient radiolabeling of trans-cyclooctene-group conjugated repebody protein using inverse-electron-demand Diels-Alder reaction. First, 1,2,4,5-tetrazine (Tz) conjugated with a DOTA chelator, was used for preparing the radiolabeled DOTA complex with ¹¹¹In. Second, the trans-cyclooctene (TCO) functionalized repebody protein was synthesized which allows for the preparation of radiolabeled proteins by copper-free click chemistry. Following incubation with the ¹¹¹In-radiolabeled DOTA complex (¹¹¹In-Tz), the TCO-functionalized RB (TCO-RB) was radiolabeled successfully with ¹¹¹In, with a high radiochemical yield (69.5%) and radiochemical purity (>99%). The radiolabeling of repebody protein by copper-free click chemistry was accomplished within 20 min, with great efficiency in aqueous conditions. These results clearly indicate that the present radiolabeling method will be useful for the efficient and convenient radiolabeling of trans-cyclooctene-group containing biomolecules.

• 대한방사성의약품학회지
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• 제5권1호
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• pp.11-17
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• 2019

Recently, antibody-like scaffold proteins have received a great deal of interest in diagnosis and therapy applications because of their intrinsic features that are often required for tumor imaging and therapy. Intrinsic issues that are associated with therapeutic application of antibody-like scaffold proteins, particularly in cancer treatment, include an efficient and straightforward radiolabeling for understanding in vivo biodistribution and excretion route, and monitoring therapeutic responses. Herein, we report an efficient and straightforward method for radiolabeling of antibody-like scaffold proteins with the $[^{99m}Tc(OH_2)_3(CO)_3]^+$ ($^{99m}Tc$-tricarbonyl) by using a site-specific direct labeling method via hexahistidine-tag, which is a widely used for general purification of recombinant proteins with His-affinity chromatography. Repebody is a new class of antibody-like scaffold protein that consists of highly diverse leucine-rich repeat (LRR) modules. Although all possible biomedical applications with repebody are ongoing, it's in vivo biodistribution and excretion pathway has not yet been explored. In this study, hexahistidine ($His_6$)-tag bearing repebody (rEgH9) was labeled with [$^{99m}Tc$]-tricarbonyl. Repebody protein was radiolabeled with high radiolabeling efficiency (>90%) and radiolabeled compound was more than 99% pure after purification. These results clearly demonstrate that the present radiolabeling method will be useful molecular imaging study.