• Korean Journal of Microbiology
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• v.29 no.5
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• pp.301-306
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• 1991

Extracellular fructosyl transferase from Aureobasidium pullulans C-23 was characterized. The molecular weight of the isolated enzyme was determined to be approximately 170,000 by SDS polyacrylamide gel electrophoresis. The enzyme has the pI value of about 3.7. The enzyme was almost completely inhibited by 5mM $Hg^{2+}$ , but was not significantly affected by other cations tested. The enzyme was inactivated by treatment of tryptophan-specific reagent N-bromo- succinimide and tyrosine-specific reagent iodine. The substrate sucrose showed protective effect on the inactivation of the enzyme by the both reagents. These results suggest that tryptophan and tyrosine residues are probably located at or near active site of the enzyme.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.243.2-244
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• 2002

Protein-tyrosine phosphatases (PTPs) constitute a family of receptor-like and cytoplasmic enzymes. which catalyze the dephosphorylation of phosphotyrosine residues in a variety of receptors and signaling molecules. Thirty subtypes of PTPs have been identified in human genomes. Among PTPs, PTP1 B has been suggested as a negative regulator of insulin signaling. Overexpression of this enzyme has been known as a cause of obesity and type II diabetes, so it is a target for drug discovery. (omitted)

• Journal of Environmental Health Sciences
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• v.30 no.4
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• pp.308-313
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• 2004

Native and acetylated soybean protein with acetylation percentage of $25\%$ were incubated with glucose to induce Maillard reaction. Acetylation of ${\varepsilon}$-amino group of lysine residues changed the conformation of soybean protein. The direct uv spectrum of native and acetylated soybean protein showed conformational changes with accessibility of tyrosine and tryptophan residues increased. Acetylation suppressed Maillard reaction between soybean protein and glucose. Acetylated soybean protein showed improved water sorption, fat binding, foam formation, and emulsion activity of the protein, but depressed brown pigment development and trypsin digestion. Thus aceylation prevented deterioration of certain functional characteristics that occurred during storage, besides causing functional characteristics to be improved on its own.

• Journal of the Korean Chemical Society
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• v.14 no.2
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• pp.161-168
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• 1970

In order to obtain the more effective evidence, supporting the hypothesis which have been previously described by former report that pepsin (EC 3.4. 4.1) forms a hydrophobic bond with the nonpolar side chain of its substrate, the inhibitory effect of carboxylic acids(from formic acid to iso-butyric acid) on the activity of pepsin to the synthetic dipeptide, N-Carbobenzoxy-L-glutamyl-L-tyrosine, was discussed. The kinetic study showed that the inhibition by carboxylic acids was competitive. The Kidecreased with increasing size of the inhibitor molecule. The $-{\Delta}F^{\circ}$increased linearly with increasing number of carbon atoms in the hydrocarbon chain of the inhibitor. It was confirmed that the hydrophobic bond between more than one side chain of amino acid residues(phenylalanine) in the binding region of the active center of pepsin and the side chain of amino acid residues in the substrate was formed as the first step of its enzymic mechanism. The inhibitory effect of carboxylic acids was due to the competition of the hydrocarbon group of the carboxylic acids with the side chain of the substrate for the hydrophobic binding site(the side chain of phenylalanine) of the pepsin.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.4
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• pp.417-426
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• 2023

The TRPM4 gene encodes a Ca²⁺-activated monovalent cation channel called transient receptor potential melastatin 4 (TRPM4) that is expressed in various tissues. Dysregulation or abnormal expression of TRPM4 has been linked to a range of diseases. We introduced the hemagglutinin (HA) tag into the extracellular S6 loop of TRPM4, resulting in an HA-tagged version called TRPM4-HA. This TRPM4-HA was developed to investigate the purification, localization, and function of TRPM4 in different physiological and pathological conditions. TRPM4-HA was successfully expressed in the intact cell membrane and exhibited similar electrophysiological properties, such as the current-voltage relationship, rapid desensitization, and current size, compared to the wild-type TRPM4. The presence of the TRPM4 inhibitor 9-phenanthrol did not affect these properties. Furthermore, a wound-healing assay showed that TRPM4-HA induced cell proliferation and migration, similar to the native TRPM4. Co-expression of protein tyrosine phosphatase, non-receptor type 6 (PTPN6 or SHP1) with TRPM4-HA led to the translocation of TRPM4-HA to the cytosol. To investigate the interaction between PTPN6 and tyrosine residues of TRPM4 in enhancing channel activity, we generated four mutants in which tyrosine (Y) residues were substituted with phenylalanine (F) at the N-terminus of TRPM4. The YF mutants displayed properties and functions similar to TRPM4-HA, except for the Y256F mutant, which showed resistance to 9-phenanthrol, suggesting that Y256 may be involved in the binding site for 9-phenanthrol. Overall, the creation of HA-tagged TRPM4 provides researchers with a valuable tool to study the role of TRPM4 in different conditions and its potential interactions with other proteins, such as PTPN6.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.6
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• pp.3669-3676
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• 2013

Faithful transmission of genetic information depends on accurate chromosome segregation as cells exit from mitosis, and errors in chromosomal segregation are catastrophic and may lead to aneuploidy which is the hallmark of cancer. In eukaryotes, an elaborate molecular control system ensures proper orchestration of events at mitotic exit. Phosphorylation of specific tyrosyl residues is a major control mechanism for cellular proliferation and the activities of protein tyrosine kinases and phosphatases must be integrated. Although mitotic kinases are well characterized, phosphatases involved in mitosis remain largely elusive. Here we identify a novel variant of mouse protein tyrosine phosphatase containing domain 1 (Ptpcd1), that we named Ptpcd2. Ptpcd1 is a Cdc14 related centrosomal phosphatase. Our newly identified Ptpcd2 shared a significant homology to yeast Cdc14p (34.1%) and other Cdc14 family of phosphatases. By subcellular fractionation Ptpcd2 was found to be enriched in the cytoplasm and nuclear pellets with catalytic phosphatase activity. By means of immunofluorescence, Ptpcd2 was spatiotemporally regulated in a cell cycle dependent manner with cytoplasmic abundance during mitosis, followed by nuclear localization during interphase. Overexpression of Ptpcd2 induced mitotic exit with decreased levels of some mitotic markers. Moreover, Ptpcd2 failed to colocalize with the centrosomal marker ${\gamma}$-tubulin, suggesting it as a non-centrosomal protein. Taken together, Ptpcd2 phosphatase appears a non-centrosomal variant of Ptpcd1 with probable mitotic functions. The identification of this new phosphatase suggests the existence of an interacting phosphatase network that controls mammalian mitosis and provides new drug targets for anticancer modalities.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.709-714
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• 2014

Protein tyrosine nitration is considered as an important indicator of nitrosative stresses and as one of the main factors for pathogenesis of inflammation and neuronal degeneration. In this study, we investigated various nitrosative modifications of bovine carbonic anhydrase II (CAII) through qualitative and semi-quantitative analysis using the combined strategy of Fourier transformation ion cyclotron resonance mass spectrometry (FT-ICR MS) and ion-trap tandem mass spectrometry (IT-MS/MS). FT-ICR MS and its spectra were used for the search of the pattern of nitrosative modifications. Identification of nitrosatively modified tyrosine sites were executed through IT-MS/MS. In addition, we also tried to infer the reason for the site-specific nitrosative modifications in CAII. In view of the above purpose, we have explored- i) the side chain accessibility, ii) the electrostatic environment originated from the acidic/basic amino acid residues neighboring to the nitrosatively modified site and iii) the existence of competing amino acid residues for nitration.

• Journal of Photoscience
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• v.9 no.2
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• pp.382-384
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• 2002

When illuminated with strong visible light, the reaction center Dl protein of photo system II is photodamage and degraded. Reactive oxygen species and endogenous cationic radicals generated by photochemical reactions are the cause of the damage to the Dl protein. Recently we found that the photodamaged Dl protein cross-links with the surrounding polypeptides such as D2 and CP43 in photosystem II. As the cross-linking reaction is dependent on the presence of oxygen, reactive oxygen species are suggested to be involved. Among the reactive oxygen species examined, ？ OH was most effective in the formation of the cross-linked products. These results indicate that the cross-linking is mostly due to ？ OH generated at photosystem II. The cross-linking site of the Dl protein is not known. As several tyrosine residues exist at the D­E loop of the Dl protein, there is a possibility that di-Tyr is formed between the D­E loop of the Dl protein and surrounding polypeptides during the strong illumination. Therefore, we examined the formation of di-Tyr using the monoclonal antibody against di-Tyr under excess illumination of the photosystem II membranes. The results obtained here suggest that no di-Tyr is formed during the excess illumination of photosystem II.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.2
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• pp.477-481
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• 2006

A clinical report indicates that 'Geijibokryunghwan(GBH) is very effective in treating thrombosis in those patients who have difficulties with more conventional antithrombotic drugs. The isolation and identification of various compounds from this plant and the same genus have been reported by several groups. However, the pharmaceutical effect of the GBH on superoxide generation in human neutrophils has not been studied. In the present report, we investigated the possibility of using herbal medicine as an alternative therapy. In particular, we studied tremor in antiatheroscleosis. In this report, we shows the GBH extract can be used as a potential atherosclerosis preventive agent in human. The effect of GBH on stimulus-induced superoxide generation and phosphorylation of tyrosine residues of protein in human neutrophils was investigated. In a conclusion, GBH suppressed tyrosine phosphorylase in a dose-dependent manner, and may have pharmacoceutical applications. These data suggest that GBH extracts merits investigation as a potential anti-atherosclerogenic agent in humans.

• YAKHAK HOEJI
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• v.40 no.2
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• pp.193-201
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• 1996

In order to study the role of C-terminal aromatic region of T4 endonuclease V in the interaction with substrate DNA, NMR and Fluorescence spectrum were recorded. Analysis of flu orescence emission spectra showed that C-terminal region of T4 endonuclease V is in or very near the binding site. In the HSQC spectrum of $^{15}N$-Tyr-labeled T4 endonuclease V*DNA complex, the broadening of a peak was observed. It is presumed that this peak corresponds to one among three tyrosine residues which belong to the WYKYY segment of C-terminal region of T4 endonuclease V. Interactions of peptide fragments consisting of C-terminal residues of T4 endonuclease V with DNAs(TT-, T^T-DNA) were investigated by NMR and Fluorescence experiment. The results suggest that two peptide fragments themselves bind to DNAs and their binding pattern is not an intercalation mode.