Sedimentation Characteristics of Ribosomal Proteins from Seeds of Pinus lambertiana

Ko, Thong-Sung 충남대학교 자연과학연구소 1981 忠南科學硏究誌 Vol.8 No.2

The ribosomal protein from seeds of Pinus lambertiana was typical in its sedimentation characteristics. The analytical ultracentrifuge pattern of the r-protein showed polydispersity in a urea-containing medium without reducing agent, indicating another criterion for physicochemical heterogeneity of the pine-seed r-proteins. However, with dithiothreitol included in the solution of the r-protein, not only the fast shoulder in the sedimentation pattern disappeared, but also the s_(20,w) value decreased from 0.5 s to 0.4 s, showing the likelihood of the influence of the reducing agent on the shape of the r-protein. The extrapolated value of the s_(20,w) to zero concentration was 1.0 s, and the M―w measured by the sedimentation-equilibrium technique was 13,000±1000.

Prossibility of the Occurrence of Acidic Ribosomal Proteins in Amide Forms

Ko, Thong-Sung 충남대학교 자연과학연구소 1980 學術硏究誌 Vol.7 No.2

Detachability of proteins from ribosomes of sugar pine seeds varied with the pI'S of the proteins Ribosomal protein bands separated by isoelectric focusing were distributed in discrete groups. Proteins most readily removed had pI's in the range of 6.3 to 7.5. The most basic (pI 8.0) and the most acidic(pI 4.5) proteins were the least detachable at each stage of ribosome washing Proteins removed from the ribosomes by each washing had higher contents of acidic amino acids and ammonia than proteins remaining in the ribosomes and there was an almost constant ratio of ammonia to acidic amino acids in the detached proteins. These data and the neutral pI's in isoelectric focusing patterns of the majority of detached proteins suggest that the acidic amino acids exist mostly in the amide form. Major isoelectric bands of detached proteins, in the pH range of 6.3-7.5, corresponded to bands of proteins that remained with the ribosomes. Differences in overall amino acid analyses between detached and bound proteins were thought to be mostly due to differential detachability of the ribosomal proteins.

Cooperative Functional Conformation Change of DNA

Ko, Thong-Sung,Huh, Joon,Myung, Pyung Keun,Park, Mun kyeu 충남대학교 자연과학연구소 1982 忠南科學硏究誌 Vol.9 No.2

Calf thymus DNA spermine의 존재하에서 polyphasic thermal structural transition phase를 나타내고, 그 Tm이 높아지며 molar transition enthalpy, cooperative length등이 커짐을 two-state transition model을 가정하여 계산하였다. 이 DNA의 삼차원적 구조 변이 시의 기능적 성질의 변화를 알기 위하여 ethidium 리간드 결합 성질 및 기질로서 효소 DNase 1에 대한 분해률의 변화등을 조사한 바 spermine이 작은 section에 결합 될 때 spermine이 결합되지 않은 부분에도, allosteric effect의 파급 효과에 의한 리간드 결합 cooperativity의 변화를 예측할 수 있었으며, spermine은 구조변이 대한 차별적 영향에 의하여 native DNA와 denatured DNA의 DNase 1에 대한 분해률에 반대효과를 가져옴을 알 수 있었다. In the presence of spermine, the thermal transition profile of calf thymus DNA has a discrete polyphasic, rather than a continous, profile, having increased Tm, molar transition enthalpy and cooperative length. Change in the ligand-binding properties in the structural transition of the DNA, induced by spermine obinding, was investigated by testing the effect of spermine on ethidium binding. Here, propagation of allosteric effect induced by spermine binding could be anticipated. In the experiment testing changes in functional properties of the DNA as a substrate to DNase 1 in structural transitions induced by spermine, spermine was shown to have apparently opposite effect on native and denatured DNA in their susceptibility to DNase 1. Viscometric titration experiment showed the possibility that the structural transitions are responsible for the change in the functional properties of the DNA as susstrate of the enzyme.

Reconciliation of Split-Site Model with Fundamentalist Formulation Enabled by Equilibrium Assumption

Ko, Thong-Sung,Ryu, Hyeong-Won,Cho, Young Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.7

By the use of multi-loop thermodynamic boxes developed here by us, we show that models of enzyme catalysis (e.g., split-site model) developed in an attempt to emphasize the importance of the reactant-state destabilization and, thus, demonstrate misleading nature of the fundamentalist position which defines Pauling's transition-state stabilization as the entire and sole source of enzyme catalytic power, should be reduced to the fundamentalist formulation which completely neglects dynamical aspects of mechanism between the reactant and the transition states and dwells only on events restricted to the reactant and transition states alone, because the splitsite (and other canonical) formulations as well as fundamentalist formulations are based, in common, on equilibrium assumptions stipulated by the thermodynamic box logics. We propose to define the equilibrium assumptions as the requisite and sufficient conditions for the fundamentalist position to enjoy its primacy as central dogma, but not as sufficient conditions for its validity, because it is subjected to contradictions presented by existing data.

Metallomicelle-Nucleic Acid Interaction: Copper (II) Dodecylsulfate-Catalyzed RNA Cleavage

Thong-Sung Ko,In-Sang Park,Hyeong-Won Ryu Korean Chemical Society 1991 Bulletin of the Korean Chemical Society Vol.12 No.4

$Cu^{2+}$-Anthraquinone Complexes : Formation, Interaction with DNA, and Biological Activity

Ko, Thong-Sung,Maeng, Hack-Young,Park, Mi-Kyeong,Park, Il-Hyun,Park, In-Sang,Kim, Byoung-Sun Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.5

Growth inhibition potency of the anthraquinones, anthraquinone-1,5-disulfonic acid and carminic acid, for Sarcoma 180 and L1210 leukemia cells in vivo and in vitro, was induced by the divalent transition metal ion, $Cu^{2+}$. On the other hand spectroscopic titration data show that the anthraquinone drugs form $Cu2^+$ chelate complexes (carminic acid : $Cu^{2+}$ = 1 : 6; anthraquinone-1,5-disulfonic acid : $Cu^{2+}$ = 1 : 3). Furthermore the $Cu^{2+}$-drug complexes associate with DNA to form the $Cu^{2+}$-anthraquinone-DNA ternary complexes. The formation of the complexes was further supported by the $H_2O_2-dependent$ DNA degradation, which can be inhibited by ethidium bromide, caused by the $Cu^{2+}$-drug complexes. It is likely that the $Cu^{2+}$-mediated cytotoxicity of the anthraquinone drugs is related with the $Cu^{2+}-mediated$ binding of the anthraquinone drugs to DNA and DNA degradation.

박테리오파지 T4 tRNA의 프로세싱에 관여하는 몇가지 RNase들

고동성,Thong-Sung Ko 대한화학회 1982 대한화학회지 Vol.26 No.6

RNase Ⅲ, RNase E, 및 RNase P가 각각 홀로 또는 복합적으로 결핍되는 E. coli 돌연변이 균주들 내에서의 박테리오파지 T4 tRNA의 전구 RNA로 부터의 합성을 연구하였다. RNase E$^-$균주에서는 9S RNA로 볼 수 있는 한 RNA 띠가 축적되었으며 RNase$ P^-$균주에서는 6S 이중띠의 하부띠가 축적되었다. RNase Ⅲ$^-$균주에서는 T4 tRNA 유전인자 떼(cluster)에 의하여 코드되는 (coded) tRNA$^{Gln}$의 생성이 심하게 억제되며 T4 DNA에 의하여는 코드되지만 T4 tRNA 유전인자 떼에 의하여 코드 되는 6S 이중 띠의 상부 띠는 RNase Ⅲ$^+$균주의 경우에 비하여 더 크게 축적된다. 그러나 6S 이중 띠의 상부 띠 RNA와 tRNA$^{Gln}$ 사이에는 precursor-product 관계가 없다고 판단되며 RNase Ⅲ이 precursor RNA을 가수분해 절단 한다고 생각하는 개념을 지지할만한 근거가 없음을 지적할 수 있다. Bacteriophage T4 tRNA processing in E. coli mutant strains defective in RNase Ⅲ, RNase E$^-$, and RNase P, respectively, singly or in combinations, was investigated. In $RNase E^- strains, a RNA band, which would be referred as 9S RNA, accumulates, while in RNase$ P^-$ strains, lower band of 6S double band is accumulated. In RNase III$^-$ strains, the production of tRAN$^{Gln}$ coded by T4 tRNA gene cluster, is severely depressed and also production of species 1 RNA, which is coded by T4 DNA but not by the tRNA gene cluster, is in somewhat depressed amounts; on the other hand, at the same time, an upper band of 6S double bands, coded by T4 tRNA gene cluster, is accumulated in rather greater amounts as compared to the RNase $^+$ strain. The upper band RNA of the 6S double band, however, does not appear to be a precursor to the tRNA$^{Gln}$. The present work points to the lack of evidence for an essential cleavage role of RNase Ⅲ, although there must be a role for the RNase Ⅲ in the T4 tRNA processing.

Nonenzymatic Degradation of RNA by Polyvinylpyrrolidone

You, Sung-Sik,Ryu, Hyeong-Won,Hwang, Seung-Jin,Jang, Hyun,Cho, Young,Ko, Thong-Sung 충남대학교 기초과학연구소 1995 忠南科學硏究誌 Vol.22 No.1

Nonenzymatic degradation of Baker's yeast RNA by polyvinylpyrrolidone (PVP) was tested, according to the procedure for the assay of ribonuclease activity, described by McDonald (1955) using MacFadyen's reagent. Significant catalytic activity of PVP for the RNA-cleavage was observed. The plot of the reaction rate vs. PVP concentration showed a bell-shaped pattern.

한국산 인삼의 여러 가지 약리작용과 세포표면막들에 대한 영향과의 상관관계

고동성,전세열 ( Thong Sung Ko,Sae Yoel Chun ) 생화학분자생물학회 1978 BMB Reports Vol.11 No.1

Effects of Nonionic Surfactants on the Solubilization and Stability of Mouse Brain Acetylcholinesterase

Young Cho,Thong Sung Ko,Seung Hee Cha,Dai Eun Sok 생화학분자생물학회 1994 BMB Reports Vol.27 No.4

A native membrane-bound form and a solubilized (purified) form of acetylcholinesterase were prepared from mouse brain, and the effects of nonionic surfactants on both solubilization of the bound enzyme and stabilization of the solubilized enzyme were investigated. For the solubilization of acetylcholinesternse from mouse brain membrane, treatment with surfactants was more effective than hydrolytic enzymes or a high ionic-strength treatment, and Triton X-100 was more efficient than an ionic surfactant. The Triton X-100-solubilized enzyme exhibited a lower K_m value (46.0 μM) than the membrane-bound enzyme (59.5 NM). This K_m value was not changed in the presence of Triton X-100. The Km value of membrane-bound enzyme decreased slightly (13%) to 51.8 μM in the presence of Triton X-100. The solubilized enzyme showed an increased (35%) V_(max) value after exposure to Triton X-100, while the V_(max) value of the membrane-bound enzyme was not significantly affected. Most of the nonionic surfactants tested effectively stabilized the solubilized enzyme. The stabilization effect of Triton X-100 increased in proportion to an increase in concentration of the surfactant, up to its critical micellar concentration. Nonionic surfactants having lower CMC values were generally more effective in the stabilization of the purified enzyme. This suggests that stabilization of solubilized acetylcholinesterase by nonionic surfactants is due to binding of the surfactants to the hydrophobic domain of the enzyme, thus keeping the enzyme in a micellar environment.