지글러-나타 촉매의 올레핀 중합반응속도 및 분자량에 관한 모사화 연구

김재하,최홍기,한종대,김일,우성일 한국고분자학회 1988 한국고분자학회 학술대회 연구논문 초록집 Vol.1988 No.10

세균성 키토산 가수분해효소의 부분적 특성

허승만,고영환,하진환,김재하 제주대학교 생명과학연구소 1999 제주생명과학연구 Vol.2 No.-

chitosan은 D-glucosamine이 β-(1→4) 결합으로 중합된 homopolymer로 chitin을 탈아세틸화(deacetylation)하여 제조된다. chitin은 갑각류의 껍질이나 곤충의 외피, 사상균체의 세포벽을 구성하고 있다. chitin, chitosan 또는 그 분해산물이나 유도체들의 산업적 효율성이 밝혀지면서, 이에 대한 연구가 활발히 이루어지고 있다. 그 중의 한 분야가 효소 분해법을 이용한 chitosan oligomer(chitosanoligosaccharides)의 생산이다. 본 연구에서는 chitosan을 분해하는 미동정 세균의 배양액으로부터 chitosan 가수분해효소(chitosanase)를 분리·정제하여, 주요 특성을 조사하였다. 세균의 무세포 배양액을 한외여과기(NMWL, 1K)로 여과하여 저분자량의 화합물을 제거한 다음 황산암모늄을 가하여 90% 포화시키고, 침전된 단백질을 회수하여 gel permeation chromatography(sephadex G-10과 G-100)로 chitosanase를 정제하였다. 정제전 효소의 비활성은 5.8U/mg 이었으나 정제과정을 통하여 9.7U/mg으로 증대되었다. 정제 전후를 통하여 SDS-PAGE 법에 의한 단백질의 분석과 효소활성 염색으로 한 종류의 chitosanase가 확인되었으며, 그 분자량은 약 30,000dalton 이었고, subunit는 한 종류인 것으로 추정되었다. chitosanase에 의한 기질의 분해산물을 한외여과와 TLC로 분석한 결과, 이 효소는 이량체에서 육량체까지의 chitosanoligosaccharides를 생산하였으며, 단량체를 생산하지 않는 특징이 있었다. 효소반응 최적온도는 40℃이었고, 50℃ 이상에서는 효소의 활성이 급격히 저하되어, 비교적 열안전성이 낮았다. 또한, 이 효소는 pH 5.0∼9.0 범위에서 1시간 방치해도 활성변화가 미미하여, 비교적 광범위한 중성영역에서 안정하였다. Chitosan is a polymer of D-glucosamine linked by β-(1→4) covalent bonds. It is obtained through deacetylation of chitin that occurs mainly in the shells of crustaceans and the exoskeletons of insects. It is also found in fungal cell walls. Having relatively rich natural resources, chitin and their derivatives are widely utilized in industries. Among those are chitosanoligosaccharides that are reported to have several biological functions. The production of chitosanoligosaccharides requires hydrolysis of chitosan by an acid or an enzyme. A chitosanase, the chitosan-depolymerizing enzyme, was purified from unidentified bacterial culture and its characteristics were determined. Cell-free culture of the unidentified bacterium was filtered with ultramembrane(NMWL, 1K) to remove low molecular weight compounds. Ammonium sulfate was added to the filtrate at the level of 90% saturation to induce precipitation of proteins. The precipitated proteins were desalted with sephadex G-10 column and fractionated through sephadex G-100 gel permeation chromatography. Specific activity of the enzyme before purification was 5.8 units/mg and was increased up to 9.7 units/mg through purification procedures. SDS-PAGE analysis of proteins and enzyme activity staining revealed only one kind of chitosanase in the bacterial culture. Its molecular weight was about 30,000 dalton with one kind of subunit. The catalytic unit could highly be a monomeric protein. TLC-analysis of enzymatic hydrolysis products of chitosan showed that the enzyme generated dimeric through hexameric oligomers of D-glucosamine without producing monomeric D-glucosamine. Its optimum temperature for catalytic activity was 40℃ and the catalytic activity dropped rapidly at the temperatures higher than 50℃, which reflected its low heat stability. The enzyme was stable for at least one hour at neutral pH ranges from 5.0∼9.0.

Thermal Oxidation of Polymer Blend Containing an Antioxidant

김재하,T . K . Kwei,Eli M . Pearce 한국고분자학회 1991 한국고분자학회 학술대회 연구논문 초록집 Vol.1991 No.10

흰쥐 심방근에서의 Purinergic 수용체의 특성

김재하,Kim, Jae-Ha 대한약리학회 1994 대한약리학잡지 Vol.30 No.2

In rat atrium the characteristics of purinergic receptors were investigated by observing the effects of some purinergic receptor agonists and antagonists on action potential and contractile force. The statistically significant effects of $ATP(10^{-6}{\sim}10^{-3}M)$ and adenosine $(10^{-6}{\sim}10^{-3}M)$ on normal action potential characteristics were a dose-dependent shortening of action potential duration $(APD_{90})$ by both agents and hyperpolarization by $ATP(10^{-4},10^{-3}M)$. $CAP(10^{-8}{\sim}10^{-4}M)$, an $A_1$ adenosine receptor agonist, shortened $(APD_{90})$ markedly in a dose-dependent manner and these effects were almost abolished by $DPCPX\;(10^{-6}\;M), an $A_1$, adenosine receptor antagonist, but not affected by $DMPX(2{\times}10^{-6}\;M)$, an $A_2$ adenosine receptor agonist. On the other hand, CGS $21680(10^{-7}{\sim}10^{-4}M)$, an $A_2$ adenosine receptor agonist, elicited a slight shortening of $(APD_{90})$ and these effects were inhibited by DPCPX but persisted in the presence of DPMX. Adenosine $(10^{-6}{\sim}10{\-4}\;M)$ decreased the basal contraction of atrial muscle in a dose-dependent manner and these effects were not inhibited by DMPX but by DPCPX. These results suggests that purinergic receptor agonists depress the cardiac activity by a short ening of action potential duration and this effect is mostly mediated by $A_1$ adenosine receptors in rat atrium.

십이지장 유두부 선암 1예

김재하,최호정,강종식,이준상 大韓消化器病學會 1989 大韓消化器病學會誌 Vol.21 No.2

Special Report 4 - 3D 입체 콘텐츠 기술

김재하,Kim, Jae-Ha 한국정보통신기술협회 2010 TTA저널 Vol.127 No.-

칼슘채널의 구조와 기능

김재하 약업신문사 1998 의약정보 Vol.1998 No.8

放射線照射에 의한 柑橘貯藏에 관한 硏究

鄭昌朝,趙漢玉,金洙賢,金在河 제주대학교 방사능이용연구소 1985 연구보고 Vol.1 No.-

柑橘의 貯藏性 向上을 爲한 ?? 線 照射가 濟州産 溫洲柑橘에 미치는 影響을 調査하였다. 溫洲柑橘 4個 系統을 10,000Ci, ?? 線源을 利用 0, 50, 100, 150Krad水準으로 照射하여 92日間 半地下式 貯藏庫에 貯藏, 調査한 結果를 要約하면 아래와 같다. 1. 貯藏終了時까지의 柑橘 累積腐敗率은 中生系인 米澤(T₂) 74.32%, 早生溫洲(T₁) 69.67%, 中晩生系林溫洲(T₃) 61.79%와 晩生系 靑島(T₄)가 64.33%였다. 反面 서울地域의 腐敗率은 D-72에서 T₁; 28%, T₃; 25% 및 T₄; 24%로 濟州地域에 比해 越等히 낮았다. 柑橘의 腐敗는 貯藏初期에 徐徐히 增加하나 照射後 59日부터는 急激히 上昇하기 始作하였다. 腐敗率과 柑橘系統 사이에는 高度의 相關關係가 있었으며 貯藏性은 T₃와 T₄가 가장 우수하였다 ??. 高放射線 照射水準(100, 150Krad)은 貯藏中期까지 柑橘貯藏에 效果가 있었으나 照射 76日 以後에는 對照區와 差가 없었다. 2. 放射線 照射는 貯藏期間中 柑橘의 酸度를 減少 시켰으며 平均 酸度는 T₁; 1.01%, T₃; 1.01%, T₄; 0.84% 및 T₂; 0.77%로 柑橘系統 및 照射線量間에는 高度(P<0.01)의 有意差가 認定되었다. 3. 모든 處理區에서 還元糖과 全糖含量은 增加하고 있었으나 統計的 有意性은 없었고 50Krad照射區에서만은 對照區에 比해 有意的(P<0.01)으로 減少하고 있었다. 糖度는 T₁,T₄가 T₂, T₃에 比하여 높았으며 高線量水準(100, 150Krad)에서 Control에 比해 有意的인 減少가 있었다(P<0.01). Ascorbine 酸含量은 모든 處理區에서 貯藏時期가 經過됨에 따라 減少하였으며 高照射線量水準에서 對照區에 比해 有意的인 減少가 있었다(P<0.01). A study was conducted to evaluate the effect of ?? irradiation on the preservation of Satsuma mandarin in Cheju Island. Four varieties (S. m. early, S. m. Komezawa, S. m. Hayashi and S. m. Aoshima) were irradiated using 10,000 Ci, ?? ray with dosages of 0, 50, 100 and 150Krad. During 92 days of storage the effects of irradiation on mandarin properties were as follows; 1. At the end of storage period the accumulated fruit rotting percentage were S. m. Komezawa (T₂); 74.32%, S. m. early (T₁); 69.67%, S. m. aoshima (T₄); 64.33% and S. m. Hayashi (T₃); 61.79%. The rottings steadily increased from the early stage of storage and rapid spoilage continued after 59 days of irradiation. A high correlation existed between fruit rotting and varieties (T₃; Y=0.78x-15.30, T₄; Y=0.79x-12.29, T₁; Y=0.93x-9.01 and T₂; Y=0.79x-13.49). High dosages (100 and 150 Krad) improved fruit preservation during the mid storage stage. However 76 days after high dose irradiation there was no significant difference a rotting between irradiated fruit and the control. 2. Irradiation decreased acidity of fruit during storage (P<0.01). The mean acidities of examined varieties were T₁; 1.01%, T₃; 1.01%, T₄; 0.84% and T₂; 0.77%. A significant differences were observed in acidity between varieties and dosages (P<0.01). 3. With one exception in all treatments, the increase in free and total sugar content was not statistically significant. The exception was the 50 Krad treatment where the total sugar content decreased. T₁and T₄showed slightly higher value of Brix than T₂and T₃and were significantly (P<0.01) decreased by higher dosage. The ascorbic acid content in all treatments decreased with length of storage and also decreased significantly with a higher dosage.

세균성 이질감염 후에 용혈성 빈혈과 급성 신부전증을 동반한 예

김재하,전성주,최두혁,박우근 임상약학사 1992 臨床藥學 Vol.12 No.6

초고온용 안테나 덮개의 기계적 특성 시험결과

김재하,황동기,최대근,Kim, Jai-Ha,Whang, Dong-Kee,Choe, Dae-Geun 한국군사과학기술학회 2007 한국군사과학기술학회지 Vol.10 No.4

This paper considers the mechanical properties test results of the ceramic fiber reinforced plastic using hyper temperature. These materials were developed to make antenna cover which should not only protect antenna from high temperature and high pressure but also transmit and receive radio frequency for hypersonic missile. So the bending strength tests under the room temperature and the hyper temperature for new materials were done to evaluate of their performances. Also, the conductivity, specific heat, diffusivity and density were tested.