서평 ( 생체막 - 김형만 지음 )

최명언 한국미생물생명공학회 ( 구 한국산업미생물학회 ) 1988 생물산업 Vol.1 No.3

The Peroxidase Activity of Rat Brain : Subcellular and Regional Distributions

최명언,Choi, Myung-Un 생화학분자생물학회 1982 한국생화학회지 Vol.15 No.4

쥐 뇌의 Peroxidase 활성도를 o-dianisidine을 이용 분광학적 방법으로 측정했다. 유사 peroxidase를 제거하기 위해 기본적인 효소측정의 여건을 살폈으며 이에 따라 세포내 및 뇌의 여섯 부위에서 peroxidase 활성도를 검토했다. 대부분의 활성도는 particulated fraction에서 발견됐으며 microsome의 고유 활성도는 mitochondria에 비해 약 두배였다. Microsome 활성도의 뇌 부위별 분포는 상당히 변화가 있어 medulla oblongata에서 가장 높았고 striatum에서는 가장 낮은 활성도를 보여 주었다. 뇌 peroxidase의 가능한 역활에 대하여 간단히 평가했다. The peroxidase activity of rat brain was determined by spectrophotometrically using o-dianisidine as substrate. Basic assay conditions were optimized in order to eliminate the pseudoperoxidase activity. The peroxidase activities were then examined in subcellular fractions as well as in six different regions of the brain. It was found that a major part of the activity was associated with particulated fractions. The specific activity of the microsomal enzyme was roughly twice as high as that of the mitochondrial. The regional distribution of the microsomal activity was quite variable. The highest activity was found in the medulla oblongata and lowest in the striatum. The possible role of the brain peroxidase was birefly assessed.

Kinetic Behavior of Solubilized Microsomal Cholesterol Ester Hydrolase of Rat Brain

최명언,Choi, Myung-Un 생화학분자생물학회 1983 한국생화학회지 Vol.16 No.4

쥐 뇌 microsome의 cholesterol ester hydrlase를 좋은 안정성과 수득율로 용해 시켰다. 최적 용해는 0.75%의 Triton X-100을 포함하는 pH7.6의 TrisHCl 완충액 1 ml당 10 mg의 microsome을 섞어 균질화하고 고속원심분리하여 이루어졌다. 이렇게 용해된 효소는 mlcrosom에 부착되었을 때 보다 더 외부에서 넣어준 지방질에 의해 그 활성도가 좌우됐으며 반응에 필요한 Triton X-100 농도는 크게 줄어 들었다. Triton X-100, 기질 및 효소의 농도를 독립적으로 변화시키면서 한 일련의 실험으로, 이 효소에 대한 계면활성제의 활성화 효과는 계면활성제의 효소에 대한 비가 계면활성제의 기질에 대한 비보다 더 중요하다는 것을 알 수 있었다. 관찰된 계면활성제의 역할은 계면활성제 존재하에서 이 효소의 반응속도론적 경향을 평가하는데 도움이 된다. Microsomal cholesterol ester hydrolase of rat brain has been solubilized with good yield and stability. The optimal solubilization was achieved by homogenization and high speed centrifugation of microsomes at 10 mg dry weight/ml of Tris-HCl buffer, pH 7.6, containing 0.75% Triton X-100. The solubilized enzyme was more dependent on exogenous lipid for activity than the microsome-bound enzyme, but the optimal concentration of Triton X-100 was greatly reduced. Series of experiments, in with concentrations of Triton X-100, the substrate, and the solubilized enzyme were varied independently, suggested that the activation effect of the detergent depended more on the ratio of detergent to enzyme than on the ratio of detergent to substrate. The observed role of detergent is helpful to evaluate the kinetic behavior of the enzyme in the presence of detergent.

쥐 간에서 메타로사이오닌 mRNA 분리 및 그의 변역

최명언,신환철,김형모 생화학분자생물학회 1991 BMB Reports Vol.19 No.3

Metallothionein(MT) messenger RNA was purified 28-fold from rat liver and was identified by its ability for the protein biosynthesis in cell-free translation systems. Total cytoplasmic RNA was extracted from the Cd injected rat liver by guanidinium thiocyanate method. The total RNA was further fractionated by oligo(dT)-cellulose affinity chromatography. For cell-free biosynthesis of MT-mRNA, rabbit reticulocyte lysate and wheat germ lysate were tested and established the optimal translational conditions for MT-mRNA. The incorporation of [^(35)S]-methionine into MT was a linear function of the amount of poly(A^+) RNA up to 1 ㎍. 4-5 mM Mg^(2+) and 75-85 mM K^+ were found to be the optimal conditions for the MT biosynthesis. Analysis of labelled product was carried out by SDS-PAGE and the gel was analyzed by H₂O₂ gel solubilization and fluorography methods. The activity of MT-mRNA was approximately, 16% and 30%, of the total RNA in the reticulocyte lysate and wheat germ system, respectively.

Enzymology of Phospholipase D : Purification and Functional Study

최명언 한국생화학분자생물학회 (구 한국생화학회) 1991 추계학술대회집 Vol.- No.-

쥐 뇌의 용해단백질 황산기 전달효소의 식별과 부분특성 연구

최명언,이지오 생화학분자생물학회 1993 BMB Reports Vol.17 No.3

Protein sulfotransferase (S) in soluble fraction of rat bran were characterized using [^(35)S] phosphoadenosinephosphosulfate (PAPS) as sulfate donor. [^(35)S] PAPS, the universal sulfate donor, was prepared enzymatically in rat liver high speed supernatant with carrier free ^(35)S0₄ and ATP. The activity of soluble protein sulfotransferase was observed in assay system containing [^(35)S] PAPS, Tris-maleate buffer pH 6.7 and soluble proteins from rate brain. The sulfated proteins were separated by SDS-PAGE and acid treatment was performed on the gel to differentiate tyrosine sulfate from carbohydrate sulfate. Incorporation of sulfate into tyrosine residues of proteins of various molecular weights was observed. Particularly high molecular weight ($gt;200 kD) proteins were more intensively sulfated. Effects of incubation time, temperature, pH, amounts of proteins, PAPS concentration, various metal ions, and some polyamino acids on the activities of protein sulfotransferases were investigated. These general properties of the soluble sulfotransferase were mostly distinct from those of the microsome associated sulfotransferase.

Microsomal Cholesterol Esterase of Rat Brain : An Integral Membrane Protein

최명언 생화학분자생물학회 1981 BMB Reports Vol.14 No.2

The biological function of reverse transcriptase in RNA tumor viruses is to catalyze synthesis of the DNA provirus, the copy of the viral RNA genome which is integrated into the host DNA. Recently, this enzyme has also been useful in genetic engineering, in which the enzyme is used for the synthesis of a certain valuable gene from the eukaryotic mRNA. Most purified reverse transcriptases from avian, rodent, feline, and simian RNA tumor viruses exhibit two enzyme activities: RNA-dependent DNA polymerase and RNase H. Two forms of reverse transcriptase have been purified from avian myeloblastosis virus and Rous sarcoma virus, and their structural relatedness between these two was observed by peptide mapping. In mammalian retroviruses, we observed so far only one species enzyme, which requires either Mn^(2+)or Mg^(2+) ion as a cation. The RNase H activity appears to be located on the separate location of the molecule and more stable. The results of radioimmunoassay showed that the reverse transcriptase contains two or three kinds of antigenic determinants.

쥐 뇌 Microsome 의 용해된 Cholesterol Ester Hydrolase 의 반응속도론적 경향

최명언 ( Myung Un Choi ) 생화학분자생물학회 1983 BMB Reports Vol.16 No.4

Microsomal cholesterol ester hydrolase of rat brain has been solubilized with good yield and stability. The optimal solubilization was achieved by homogenization and high speed centrifugation of microsomes at 10 ㎎ dry weight/㎖ of Tris-HCl buffer, pH 7.6, containing 0. 75 % Triton X-100. The solubilized enzyme was more dependent on exogenous lipid for activity than the microsome-bound enzyme, but the optimal concentration of Triton X-100 was greatly reduced. Series of experiments, in with concentrations of Triton X-100, the substrate, and the solubilized enzyme were varied independently, suggested that the activation effect of the detergent depended more on the ratio of detergent to enzyme than on the ratio of detergent to substrate. The observed role of detergent is helpful to evaluate the kinetic behavior of the enzyme in the presence of detergent.

쥐 뇌의 Peroxidase 활성도 세포내 및 뇌 부위별 분포

최명언 ( Myung Un Choi ) 생화학분자생물학회 1982 BMB Reports Vol.15 No.4

The peroxidase activity of rat brain was determined by spectrophotometrically using o-dianisidine as substrate. Basic assay conditions were optimized in order to eliminate the pseudoperoxidase activity. The peroxidase activities were then examined in subcellular fractions as well as in six different regions of the brain. It was found that a major part of the activity was associated with particulated fractions. The specific activity of the microsomal enzyme was roughly twice as high as that of the mitochondrial. The regional distribution of the microsomal activity was quite variable. The highest activity was found in the medulla oblongata and lowest in the striatum. The possible role of the brain peroxidase was birefly assessed.

포리포리파제 D 의 정제 및 활성화 부위 특성연구

이혜영,최명언,고은희 ( Hay Young Lee,Myung Un Choi,Eun Hie Koh ) 생화학분자생물학회 1989 BMB Reports Vol.22 No.4

Phospholipase D has been partially purified from an acetone powder of savoy cabbage in an overall yield of 10%. The purification involves gel filtration on Sephadex G-200, ion-exchange chromatography on DEAE-cellulose, and hydrophobic affinity chromatography using γ-aminopropane agarose gel. The purity of about 80% and molecular weight of 89,000 were estimated on the basis of gel electrophoresis. The specific activities of the partially purified enzyme was 428 μmole/min/㎎ protein in MES buffer, pH 6.3, containing 4 mM phosphatidylcholine, 2 mM SDS and 10 mM CaCl₂ at 37℃. Calcium ion is essential to the enzyme activity but is not involved in the heat stability of the enzyme. To characterize the active site of the enzyme, the following chemicals were examined; N-ethylmaleimide, p-chloromercuribenzoate, p-bromophenacylbromide, and diethylpyrocarbonate. The enzymatic activity was lost completely by cysteine group modifying reagents and it was found that there was at least one histidine group in the active site.