• Journal of Pharmaceutical Investigation
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• 제25권3호spc1호
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• pp.7-20
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• 1995

Taurine, a ${\beta}-amino$ acid, plays an important role as a neuromodulator and is necessary for the normal development of the brain. Since de novo synthesis of taurine in the brain is minimal and in vivo studies suggest that taurine dose not cross the blood-brain barrier, we examined whether the choroid plexus, the blood-cerebrospinal fluid (CSF) barrier, plays a role in taurine transport in the central nervous system. The uptake of $[^3H]-taurine$ into ATP depleted choroid plexus from rabbit was substantially greater in the presence of an inwardly directed $Na^+$ gradient taurine accumulation was negligible. A transient in side-negative potential gradient enhanced the $Na^+-driven$ uptake of taurine into the tissue slices, suggesting that the transport process is electrogenic, $Na^+-driven$ taurine uptake was saturable with an estimated $V_{max}$ of $111\;{\pm}\;20.2\;nmole/g/15\;min$ and a $K_M\;of\;99.8{\pm}29.9\;{\mu}M$. The estimated coupling ratio of $Na^+$ and taurine was $1.80\;{\pm}\;0.122.$ $Na^+-dependent$ taurine uptake was significantly inhibited by ${\beta}-amino$ acids, but not by ${\alpha}-amino$ acids, indicating that the transporter is selective for ${\beta}-amino$ acids. Since it is known that the physiological concentration of taurine in the CSF is lower than that in the plasma, the active transport system we characterized may face the brush border (i.e., CSF facing) side of the choroid plexus and actively transport taurine out of the CSF. Therefore, we examined in vivo elimination of taurine from the CSF in the rat to determine whether elimination kinetics of taurine from the CSF is consistent with the in vitro study. Using a stereotaxic device, cannulaes were placed into the lateral ventricle and the cisterna magna of the rat. Radio-labelled taurine and inulin (a marker of CSF flow) were injected into the lateral ventricle, and the concentrations of the labelled compounds in the CSF were monitored for upto 3 hrs in the cisterna magna. The apparent clearance of taurine from CSF was greater than the estimated CSF flow (p<0.005) indicating that there is a clearance process in addition to the CSF flow. Taurine distribution into the choroid plexus was at least 10 fold higher than that found in other brain areas (e. g., cerebellum, olfactory bulb and cortex). When unlabelled taurine was co-administered with radio-labelled taurine, the apparent clearance of taurine was reduced (p<0.0l), suggesting a saturable disposition of taurine from CSF. Distribution of taurine into the choroid plexus, cerebellum, olfactory bulb and cortex was similarly diminished, indicating that the saturable uptake of taurine into these tissues is responsible for the non-linear disposition. A pharmacokinetic model involving first order elimination and saturable distribution described these data adequately. The Michaelis-Menten rate constant estimated from in vivo elimination study is similar to that obtained in the in vitro uptake experiment. Collectively, our results demonstrate that taurine is transported in the choroid plexus via a $Na^+-dependent,saturable$ and apparently ${\beta}-amino$ acid selective mechanism. This process may be functionally relevant to taurine homeostasis in the brain.

• BMB Reports
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• 제36권6호
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• pp.545-551
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• 2003

A cDNA of bovine brain glutamate dehydrogenase (GDH) was isolated from a cDNA library by recombinant PCR. The isolated cDNA has an open-reading frame of 1677 nucleotides, which codes for 559 amino acids. The expression of the recombinant bovine brain GDH enzyme was achieved in E. coli. BL21 (DE3) by using the pET-15b expression vector containing a T7 promoter. The recombinant GDH protein was also purified and characterized. The amino acid sequence was found 90% homologous to the human GDH. The molecular mass of the expressed GDH enzyme was estimated as 50 kDa by SDS-PAGE and Western blot using monoclonal antibodies against bovine brain GDH. The kinetic parameters of the expressed recombinant GDH enzymes were quite similar to those of the purified bovine brain GDH. The $K_m$ and $V_{max}$ values for $NAD^+$ were 0.1 mM and $1.08\;{\mu}mol/min/mg$, respectively. The catalytic activities of the recombinant GDH enzymes were inhibited by ATP in a concentration-dependent manner over the range of 10 - $100\;{\mu}M$, whereas, ADP increased the enzyme activity up to 2.3-fold. These results indicate that the recombinant-expressed bovine brain GDH that is produced has biochemical properties that are very similar to those of the purified GDH enzyme.

• Journal of Microbiology and Biotechnology
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• 제28권4호
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• pp.606-612
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• 2018

The enzyme xylose isomerase (E.C. 5.3.1.5, XI) is responsible for the conversion of an aldose to ketose, especially xylose to xylulose. Owing to the ability of XI to isomerize glucose to fructose, this enzyme is used in the food industry to prepare high-fructose corn syrup. Therefore, we studied the characteristics of XI from Anoxybacillus kamchatkensis G10, a thermophilic bacterium. First, the gene coding for XI (xylA) was inserted into the pET-21a(+) expression vector and the construct was transformed into the Escherichia coli competent cell BL21 (DE3). The expression of recombinant XI was induced in the absence of isopropyl-thio-${\beta}$-galactopyranoside and purified using Ni-NTA affinity chromatography. The optimum temperature of recombinant XI was $80^{\circ}C$ and measurement of the heat stability indicated that 55% of residual activity was maintained after 2 h incubation at $60^{\circ}C$. The optimum pH was found to be 7.5 in sodium phosphate buffer. Magnesium, manganese, and cobalt ions were found to increase the enzyme activity; manganese was the most effective. Additionally, recombinant XI was resistant to the presence of $Ca^{2+}$ and $Zn^{2+}$ ions. The kinetic properties, $K_m$ and $V_{max}$, were calculated as 81.44 mM and $2.237{\mu}mol/min/mg$, respectively. Through redundancy analysis, XI of A. kamchatkensis G10 was classified into a family containing type II XIs produced by the genera Geobacillus, Bacillus, and Thermotoga. These results suggested that the thermostable nature of XI of A. kamchatkensis G10 may be advantageous in industrial applications and food processing.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVI)
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• pp.327-333
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• 2005

Dihydroxy-acid dehydratase (DHAD, 2,3-dihydroxy-acid hydrolyase, EC 4.2.1.9) is one of the key enzymes involved in the biosynthetic pathway of the branched chain amino acid isoleucine and valine. Although the enzyme have been purified and characterized in various mesophiles including bacteria and eukarya, the biochemical properties of DHAD has bee not yet reported from hyperthermophilic archaea. In this study, we cloned, expressed, and purified a DHAD homologue from the thermoacidophilic archaeon Sulfolobus solfataricus P2, which grows optimally at $80\;^{\circ}C$ and pH 3, in E. coli. Characterization of the recombinant S. solfataricus DHAD (rSso_DHAD) revealed that it is the dimeric protein with a subunit molecular weight of 64,000 Da in native structure. rDHAD showed the highest activity toward 2,3-dihydroxyisovaleric acid among 17 aldonic acid substrates Interestingly, this enzyme also displayed 50 % activities toward some pentonic acids and hexonic acids when compared with the activity of this enzyme to the natural substrate. Moreover, rSso_DHAD indicated relatively higher activity toward D-gluconate than any other hexonic acids tested in substrates. $K_m$ and $V_{max}$ values of rSso_DHAD were calculated as $0.54\;{\pm}\;0.04\;mM$ toward 2,3dihydroxyisovalerate and $2.42\;{\pm}\;0.19\;mM$ toward D-gluconate, and as $21.6\;{\pm}\;0.4\;U/mg$ toward 2,3-dihydroxyisovalerate and $13.8\;{\pm}\;0.4\;U/mg$ toward D-gluconate, respectively. In the study for biochemical properties, the enzyme shows maximal activity between $70^{\circ}C$ and $80^{\circ}C$, and the pH range of pH 7.5 to 8.5. The half life time at $80^{\circ}C$ was 30 min. A divalent metal ion, $Mn^{2+}$, was only powerful activators, whereas other metal ions made the enzyme activity reduced. $Hg^{2+}$, organic mercury, and EDTA also strongly inhibited enzyme activities. Particularly, the rSso_DHAD activity was very stable under aerobic condition although the counterparts reported from mesophiles had been deactivated by oxygen.

• Tuberculosis and Respiratory Diseases
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• 제46권6호
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• pp.795-802
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• 1999

연구배경 : 만성폐쇄성 폐질환에서 운동부하 심폐기능검사(이하 운동검사)는 환자에 대한 운동처방이나 수술전의 위험성 평가 동의 목적에 유용하게 이용된다. 운동검사에 포함된 여러 지표들은 최대운동(maximal exercise) 시점에서의 값이 주로 이용되므로 환자가 조기에 운동을 중단하여 최대운동에 도달하지 못하면 심폐기능의 적절한 평가가 어려우며 따라서 이런 경우에도 유용할 수 있는 지표의 개발이 필요하다. 최대운동시의 예비호흡지수는 최대운동중의 환기량과 최대환기량의 비율($V_{Emax}$/MVV)로 만성폐쇄성 폐질환에서는 대부분 비정상적으로 증가된 소견을 보인다. 만일 만성폐쇄성 폐질환 환자에서 최대운동시 뿐만 아니라 무산소역치에서의 예비호흡지수도 역시 증가되어 있다면 최대운동에 도달하지 못한 환자의 운동검사 결과의 해석에 유용할 것으로 판단된다. 방 법 : 만성폐쇄성 폐질환 환자 36명(남 34명, 여 2명)과 정상대조군 42명(남 22명, 여 20명)을 대상으로 운동부하 심폐기능검사를 시행하였다. 결 과 : 만성폐쇄성 폐질환 환자의 FVC(mean$\pm$SE) $3102.8{\pm}132.7mL$, $FEV_1$ (mean$\pm$SE) $1754.7{\pm}108.6mL$, $FEV_1/FVC$ $54.94{\pm}1.62$% 이었으며 정상대조군에서는 FVC(mean$\pm$SE) $4429.3{\pm}142.4mL$, $FEV_1$ (mean$\pm$SE) $3808.6{\pm}111.1mL$, $FEV_1$/FVC $86.05{\pm}0.80$% 이었다. 만성페쇄성 폐질환 환자와 정상대조군의 $VO_{2max}$의 평균은 $1.06{\pm}0.07L/min$와 $2.14{\pm}0.09L/min$ 였으며(p<0.01), 예상치에 대한 백분율은 각각 $54.3{\pm}3.0$%와 $86.0{\pm}1.9$% 이었다(p<0.05). R값 1.09를 기준으로 만성 폐쇄성 폐질환 환자에서 최대운동에 도달한 사람은 36명 중 7명(19.4%), 정상대조군에서는 42명 중 18명(42.9%)이었다. 만성폐쇄성 폐질환 환자와 정상대조군의 무산소역치에서의 예비호흡지수는 $0.50{\pm}0.03$과 $0.28{\pm}0.02$이었다(p<0.01). 최대운동을 수행한 만성폐쇄성 폐질환 환자에서 무산소역치에서의 예비호흡지수과 최대운동시의 예비호흡지수는 유의한 상관관계를 보였다(r=0.9687, p<0.01). 결 론 : 무산소역치에서의 예비호흡지수는 만성폐쇄성 폐질환 환자군과 정상대조군사이에 유의한 차이를 보였으며, 최대운동에서의 예비호흡지수와도 유의한 상관관계를 보였다. 따라서 무산소역치에서의 예비호흡지수는 최대운동에 이르지 못한 만성폐쇄성 폐질환 환자의 평가 지표로 유용할 것으로 판단된다.

• 한국유통학회:학술대회논문집
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• 한국유통학회 2001년도 추계학술대회 발표논문집
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• pp.125-141
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• 2001

이번 연구는 통합물류정보시스템 개발에 관한 것이다. 글러벌 경제시대에 기업경쟁력 확보를 위하여 효율적이고 경제적인 물류체제 구축이 요구되어지고 있다. 그러나 한국의 매출액대비 기업 물류비는 1997년 기준으로 12.9%로서 미국 9.0%, 일본 6.4%에 비하여 매우 높다. 이는 국내 물류 업체가 영세하고 물류 정보 인프라가 취약하기 때문이다. 따라서 국내 물류 체재 개선을 위해서 새로운 물류프로세스의 도입과 효율적인 물류시스템의 개발이 절실하다. 이에 따라 기업이 물류 아웃소싱을 통해 전체 물류 프로세스의 효율성을 재고하기 위한 제3자 물류가 대두되고 있다. 그리고 제3자 물류에서 더 나아가, 기업이 요구하는 물류 서비스 요건을 독자적으로 충족시킬 수 있도록 정보기술, 컨설팅 능력을 보유한 업체가 다수의 물류 업체 운영 및 관리를 최적화하는 제4자 물류가 등장하였다. 이번 연구의 목적은 웹 기반에서 제4자 물류를 지원해줄 수 있는 통합물류 정보시스템을 개발하는 것이다. 이를 위하여 이번 연구는 먼저 국내 물류 산업의 현황과 문제점을 살펴보았다. 그리고 현재 물류 체제 개선을 위한 대안으로서 대두되고 있는 제3자 물류와 제4자 물류의 개념을 살펴보았다. 그리고 택배사, 운송사와 같은 다수의 물류 서비스 공급자와 쇼핑몰, 제조업체와 같은 다수의 물류 서비스 수요자 사이에서 물류중개 서비스를 제공하고, 물류 서비스의 정보화를 지원할 수 있는 KT-Logis를 개발하였다. 화주기업이 KT-Logis를 통한 제4자 물류를 도입하면 물류유통단계 축소를 통한 물류 비용의 절감과 물류 서비스 향상을 기대할 수 있다. 또한 물류업체는 KT-Logis를 이용하여 공차율 감소, 적재율 향상 등과 같은 물류 프로세스 향상을 기대할 수 있다.으로 기대된다.로서 수동발골육(手動拔骨肉)의 미생물수(微生物數)와 큰 차이가 없었다.출된 하수 슬러지의 분해속도상수와 기질의 분율 및 분해패턴을 토대로 혐기성소화시 효율적이고 경제적인 HRT의 산정이 가능하다.은 약 4.5 kDa으로_ 확인되었다. 따라서 B. subtilis MJP1은 항진균 활성과 항세균 활성을 가진 bacteriocin-like substances를 생산함을 알 수 있고 이와 같은 새로운 항미생물 물질은 천연 식품보존제 및 사료보존제 뿐만 아니라 항생제 대체 의약품으로도 활용이 기대되며, 이를 위하여 향후 이 물질들의 보다 정확한 구조 및 특성 규명 등의 연구가 필요하다.성도는 1시간째에 최저로 떨어지다가(대조치의 89%, p<0.05)이후 회복하기 시작하여 24시간째에 약간 대조치 이상으로 회복되었다. 5-HT의 turnover rate는 MAO활성도 변화와 거의 같은 변화를 보였다. 2) 만성투여시 (하루 2번, 14일간 투여)는 5-HT 함량, 5-HIAA 함량, MAO 활성도 및 5-HT turnover rate 모두가 중등도로 감소되었다. (각각 대조치의 87%, 69%, 80%, 79%). 3) MAO 활성도와 5-HT turnover rate 사이에는 높은 상관관계가 있었다. (r=0.866, p<0.001, N=94). 4) MAO 활성도의 역동학 실험에서는 대조치에 비해 투여군에서 Km 값은 의미가 있는 증가가 있었으나 $V_{max}$값은 큰 변동이 없었다. 5) d-amphetamine을 급성 투여할때는 sleeping과 lying components는 상당한 감소를 보인 반면, locomotor activity 는 1시간까지는 상당한 증가를 보였으며 용량이 적을수록 더 큰