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폴리에틸렌 글리콜의 공유부착에 의한 Adenosine Deaminase 의 성질변화에 관한 연구
김동규,김은진,강신원,김승원 ( Dong Kyoo Kim,eun Jin Kim,Shin Won Kang,Seung Won Kim ) 생화학분자생물학회 1993 BMB Reports Vol.26 No.1
The adenosine deaminase from calf intestinal mucosa was modified with 2,4-bis(o-methoxy-polyethylene glycol)-6-chloro-s-triazine(activated PEG), which was synthesized from monomethoxypolyethylene glycol(MW 5,000) and cyanuric chloride. Approximately 41 out of the total 69 amino groups in the adenosine deaminase molecule were modified. The conjugation of PEG increased affinity for adenosine showed by decreased K_m. ADA and PEG-ADA had temperature optima of 60℃ and 50℃, respectively. Thermal inactivation at temperature above optima was essentially the same for the native and modified enzyme. PEG-ADA and ADA demonstrated an resistance to proteolytic digestion of trypsin and chymotrypsin. Modification of the adenosine deaminase with PEG resulted in greatly decreased electrophoretic mobility of the protein. The modified ADA preparations were less immunogenic and antigenic than native enzyme as determined by immunodiffusion studies.
Alteration of Some Properties of Adenosine Deaminase by Covalent Attachment of Polyethylene Glycol
김동규,김은진,강신원,김승원,Kim, Dong-Kyoo,Kim, Eun-Jin,Kang, Shin-Won,Kimm, Seung-Won 생화학분자생물학회 1993 한국생화학회지 Vol.26 No.1
Adenosine deaminase의 69개 아미노기중 41개를 cyanuric chloride로 활성화된 PEG로 공유부착시켰다. PEG가 결합하더라도 ADA의 활성은 유지되었고, $K_m$값은 감소해 기질에 대한 친화성은 증가하였다. 또한 원래 ADA에 비하여 산성범위에서 활성이 감소된 좁은 pH의존성을 보였다. ADA와 PEG-ADA는 각각 $60^{\circ}C$와 $50^{\circ}C$가 최적온도이었고 높은 온도에서 열에 의한 활성감소는 두 효소 모두 동일한 양상을 나타내었다. PEG-ADA는 trypsin이냐 chymotrypsin 같은 단백질 분해효소에 의해서 가수분해는 되지 않았다. ADA는 polyacrylamide gel에서 정상적인 이동도를 보인 반면 PEG-ADA는 전기이동도가 현저하게 감소된 결과를 보였다. PEG-ADA는 면역원성이나 항원성이 현저히 감소하였다. 항ADA 혈청은 ADA와 침전반응을 하였지만 항PEG-ADA 혈청은 PEG-ADA와 반응하지 않았다. The adenosine deaminase from calf intestinal mucosa was modified with 2,4-bis(o-methoxy-polyethylene glycol)-6-chloro-s-triazine(activated PEG), which was synthesized from monometh-oxypolyethylene glycol(MW 5,000) and cyanuric chloride. Approximately 41 out of the total 69 amino groups in the adenosine deaminase molecule were modified. The conjugation of PEG increased affinity for adenosine showed by decreased $K_m$. ADA and PEG-ADA had temperature optima of $60^{\circ}C$ and $50^{\circ}C$, respectively. Thermal inactivation at temperature above optima was essentially the same for the native and modified enzyme. PEG-ADA and ADA demonstrated an resistance to proteolytic digestion of trypsin and chymotrypsin. Modification of the adenosine deaminase with PEG resulted in greatly decreased electrophoretic mobility of the protein. The modified ADA preparations were less immunogenic and antigenic than native enzyme as determined by immunodiffusion studies.
영상회의 시스템을 위한 RTP/RTCP 구현 및 오디오 데이터 전송을 이용한 QoS 분석
김동규(Kim Dong Kyoo),강민규(Kang Min Gyu),황승구(Hwang Seung Koo) 한국정보처리학회 1998 정보처리학회논문지 Vol.5 No.12
This paper describes the design and the implementation of the Realtime Transport Protocol(RTP)/Realtime Control Protocol(RTCP) (RFC 1889, 1890) that is used to trnsmit the audio/video data to any destination and to feedback the Quality of Service(QoS) information of the received media data to the sender, in the teleconferencing systems proposed by ITU-T. These protocols are implemented with multi-thread technique and run on top of UDP/IP-Multicast through the socket interfeace as the underlying protocol. The upper layer is implemented such that it can be accessed by the H.245 conference control protocol. The RTP packetizes the digitized audio/video data from the encoder into a fixed format, and multicast to the participants. The RTCP monitors RTP packets and extracts the QoS values from it such as round-trip delay, jitter and packet loss to form RTCP packets and non-periodically sends them to the sender site. In this paper, we also describe the study of measurement and analysis for QoS factors that observed on performing teleconferencing system over Internet. The results from this experiment is indicate that RTT and Jitter value are acceptable even network load is high. However, it appears that packet loss rate is high in daytime and most losses periods have length one or two.