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Paik, Seung-R.,Kim, Do-Hyung,Chang, Chung-Soon Korean Society for Biochemistry and Molecular Biol 1996 Journal of biochemistry and molecular biology Vol.29 No.3
Effects on thrombin by an amphipathic cation, dequalinium, which has been recognized as an anticarcinoma agent were investigated with small chromogenic substrates such as Na-benzoyl-DL-argininep-nitroanilide (BApNA), H-D-phenylalanyl-L-pipecoyl-L-arginine-p-nitroanilide (S-2238), and Na-p-tosyl-L-arginine methyl ester (TAME). Among them, only TAME hydrolysis due to an esterase activity of the enzyme was significantly activated to 81% at 20 ${\mu}M$ dequalinium in the absence of NaCl. This stimulation became even higher in the presence of 0.2 M NaCl to 3.5-fold at 60 ${\mu}M$ dequalinium. This specific activation of thrombin was well correlated with the results of in vitro coagulation tests measuring the activated partial thromboplastin time (APTT) and the prothrombin time (PT) It is pertinent. therefore, to suggest that the esterase activity should be examined in addition to the effects on 5-2238 hydrolysis when especially any regulators not directed to an active site of thrombin need to be studied. We also expect that dequalinium could be a useful tool for studying structure-function relationship of thrombin and blood coagulation.
Paik, Seung-R.,Woo, Jeong-Im,Kim, Gyoung-Mi,Cho, Jin-Mo,Yu, Kyoung-Hee,Chang, Chung-Soon Korean Society for Biochemistry and Molecular Biol 1997 Journal of biochemistry and molecular biology Vol.30 No.1
Earthworm extracts are known for anti-inflammatory, analgesic. antipyretic, and anticancer effects but can also influence blood circulation. It was previously shown that an earthworm, Lumbricus rubelius. contained a water-extractable anticoagulant which was a heat- and acid-stable molecule with hydrophilic property. In order to uncover the biochemical nature of this molecule, the anticoagulant was processed with various hydrolases such as trypsin, DNase, RNase. and lysozome. When the digested samples were analyzed with an in vitro coagulation test measuring activated partial thromboplastin time (APTT) and agarose gel electrophoresis, the anticoagulant proved to be a relatively homogeneous DNA fragment with relative molecular size around 72 base pairs. Interestingly, the activity was further stimulated with a trypsin digestion. RNA. on the other hand, did not prolong the APTT. It was also demonstrated that the DNA accelerated the antithrombin III (AT-III) inhibition of thrombin from $IC_{50}$ of 0.34 to 0.16 unit determined with S-2238 as a substrate, whereas heparin, a popular anticoagulant. shifted the value to 0.05. Therefore, it is suggested that the DNA could be considered as an alternative antithrombotic agent to heparin, which would exhibits bleeding side effects.
Enantiomeric separation of some flavanones using shinorhizobial linear octasaccharides in CE
Kwon, Chanho,Paik, Seung R.,Jung, Seunho WILEY-VCH Verlag 2008 Electrophoresis Vol.29 No.20
<P>Succinoglycan, a shinorhizobial exopolysaccharide produced by Shinorhizobium meliloti, is composed of an octasaccharide subunit. S. meliloti produces both high-molecular-weight and low-molecular-weight (M<SUB>r</SUB><10 000) succinoglycans that consisted of monomer, dimer, or trimer of an octasaccharide unit. We isolated and purified the monomer among low-molecular-weight succinoglycans and used this microbial linear octasaccharide as a novel chiral additive for enantiomeric separation of some flavanones such as homoeriodictyol, hesperetin, naringenin, and isosakuranetin in CE. Throughout the present investigation, we firstly used noncyclic oligosaccharides for the chiral separation of flavanones. We also found that successful enantioseparation of four flavanones depends on the presence of succinate substituents of the linear monomeric octasaccharide in CE, suggesting that succinylation of succinoglycan monomer is decisive for the effective enantiomeric separation.</P>
Amino acid sequence motifs and mechanistic features of the membrane translocation of &agr;-synuclein
Ahn, Keun Jae,Paik, Seung R.,Chung, Kwang Chul,Kim, Jongsun Blackwell Publishing Ltd 2006 Journal of Neurochemistry Vol.97 No.1
<P>Abstract</P><P>Many lines of evidence suggest that &agr;-synuclein can be secreted from cells and can penetrate into them, although the detailed mechanism is not known. In this study, we investigated the amino acid sequence motifs required for the membrane translocation of &agr;-synuclein, and the mechanistic features of the phenomenon. We first showed that not only &agr;-synuclein but also &bgr;- and &ggr;-synucleins penetrated into live cells, indicating that the conserved N-terminal region might be responsible for the membrane translocation. Using a series of deletion mutants, we demonstrated that the 11-amino acid imperfect repeats found in synuclein family members play a critical role in the membrane translocation of these proteins. We further demonstrated that fusion peptides containing the 11-amino acid imperfect repeats of &agr;-synuclein can transverse the plasma membrane, and that the membrane translocation efficiency is optimal when the peptide contains two repeat motifs. &agr;-Synuclein appeared to be imported rapidly and efficiently into cells, with detectable protein in the cytoplasm within 5 min after exogenous treatment. Interestingly, the import of &agr;-synuclein at 4°C was comparable with the import observed at 37°C. Furthermore, membrane translocation of &agr;-synuclein was not significantly affected by treatment with inhibitors of endocytosis. These results suggest that the internalization of &agr;-synuclein is temperature-insensitive and occurs very rapidly via a mechanism distinct from normal endocytosis.</P>
Evidence for Existence of a Water - Extractable Anticoagulant in an Earthworm , Lumbricus rubellus
Chang, Chung Soon,Paik, Seung R,Woo, Jeong Im,Bahk, Yun Kyung,Yu, Kyoung Hee 생화학분자생물학회 1982 BMB Reports Vol.29 No.6
We have isolated a water-extracted novel regulator for blood coagulation from an earthworm. Lumbricus rubellus. As a folk remedy, the earthworm has been known to facilitate blood circulation. After complete heat inactivation of endogenous proteases in the earthworm, an anticoagulants) was purified through ammonium sulfate fractionation and three consecutive gel permeation chromatography of Sephacryl S-300, Sephadex G-75, and G-150 by measuring activated partial thromboplastin time (APTT). The anticoagulant was further purified to 2,800 fold with a C4 reversed-phase HPLC. This activity was stable under heat (100℃ for 30 min) and acidic conditions (0.4 N HCl). The effects of this partially purified anticoagulant on thrombin were observed with various substrates such as Nα-benzoyl-DL-arginine-p-nitroanilide (BApNA), H-D-phenylalanyl-L-pipecoyl-L-arginine-p-nitroanilide (S-2238), Nα-p-tosyl-L-arginine methyl ester (TAME), and fibrinogen as a natural substrate. Only TAME hydrolysis, due to an esterase activity of the enzyme, was inhibited among the chromogenic substrates. In addition, the anticoagulant not only inhibited the conversion of fibrinogen to fibrin but also prolonged the fibrin clot formation monitored with the in vitro coagulation test. Based on these observations, we suggest the significance of measuring the ability of antithrombotic drugs to inhibit the esterase activity of thrombin. In this report. it was also shown that the earthworm indeed contained a water-extractable, heat- and acid-stable anticoagulant which could be used as a novel antithrombotic agent.