• Molecules and Cells
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• 제43권10호
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• pp.841-847
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• 2020

Histone acetylation and deacetylation play central roles in the regulation of chromatin structure and transcription by RNA polymerase II (RNA Pol II). Although Hda1 histone deacetylase complex (Hda1C) is known to selectively deacetylate histone H3 and H2B to repress transcription, previous studies have suggested its potential roles in histone H4 deacetylation. Recently, we have shown that Hda1C has two distinct functions in histone deacetylation and transcription. Histone H4-specific deacetylation at highly transcribed genes negatively regulates RNA Pol II elongation and H3 deacetylation at inactive genes fine-tunes the kinetics of gene induction upon environmental changes. Here, we review the recent understandings of transcriptional regulation via histone deacetylation by Hda1C. In addition, we discuss the potential mechanisms for histone substrate switching by Hda1C, depending on transcriptional frequency and activity.

• 한국의류학회지
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• 제20권4호
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• pp.682-689
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• 1996

A preparative method has been proposed for obtaining chitosan products which have a desired degree of deacetylation (DD, %) without much decrease in molecular weight. Deacetylation was prepared by two methods. The method I which was proposed by Domard etc. was that DMSO/thiophenol was used repeatedly only during the deacetylation, the method II was that DMSO/thiophenol was used after the alkali treatment. Then, effective deacetylation was performed by the method ll. To determine the degree of deacetylation, potentiometric titration method was adopted. According to the increase of DD, the viscosity average moleclar weght $(\overline{M\upsilon}$) and the DP of the chitosan products were decreased. The intensity of FT-lR peak appeared at $1655cm^{-1}, which was characteristic peak of amide I (Nacetyl secondary amide group), was gradually decreased with deacetylation. X-ray analysis showed that the lattice-spacing in the chitosan film increased with the degree of deacetylation, but the difference of the transparency of the chitosan products was not diverged significantly.

• 한국식품과학회지
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• 제31권2호
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• pp.558-563
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• 1999

반응표면분석에 의하여 chitosan 제조조건에 따른 chtosan의 이화학적 특성을 모니터링하였다. 탈아세틸화도는 NaOH 농도가 증가함에 따라 급격히 감소하였다. Chitosan의 용해도는 NaOH 농도가 51%에서 가장 높았으며, 탈아세틸화 온도 및 시간은 각각 $109^{\circ}C$, 123분에서 가장 높았다. Chitosan의 점도에 대한 탈아세틸화 조건의 영향은 NaOH농도의 영향을 주로 받고 있었다. Chitin의 탈아세틸화에 따른 chitosan의 최적 제조조건범위는 NaOH 농도$(52{\sim}54%)$, 탈아세틸화 온도$(100{\sim}115^{\circ}C)$ 및 탈아세틸화 시간$(100{\sim}140\;min)$이었다.

• 한국수산과학회지
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• 제28권4호
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• pp.392-396
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• 1995

Chitosan의 탈아세틸화도와 분자량에 미치는 chitosan 제조조건의 영향을 조사한 결과는 다음과 같다. 탈아세틸화 과정에서 NaOH 농도가 높을수록 탈아세틸화는 많이 일어났으나 $40\%$ 이상의 농도에서는 농도가 증가할수록 탈아세틸화의 증가폭은 감소하고, 분자량의 감소폭은 줄어들지 않았다. 가열온도를 $130^{\circ}C$ 에서 $150^{\circ}C$로 증가시켰을 때 탈아세틸화도는 $84\%$에서 $87\%$로 $3\%$ 정도 증가한 반면 분자량은 267,000에서 85,800로 $90^{\circ}C$에서 $130^{\circ}C$로 증가하였을 때의 분자량 감소폭보다 크게 나타났다. 그리고 3시간 이상 연속 알칼리처리하여도 $86\%$ 이상의 탈아세틸화도를 얻지 못하였지만 간헐적으로 수세하여 처리한 경우 3회 처리하였을 때 $93\%$의 탈아세틸화가 일어났다. 연속으로 3시간 처리했을 경우 탈아세틸화도는 $84\%$이었고, 분자량은 267,000이었으나 간헐반복처리로 3시간처리 했을 때는 탈아세틸화도가 $93\%$, 분자량은 280,000으로 연속처리 한 경우보다 더 높았다.

• BMB Reports
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• 제45권8호
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• pp.458-463
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• 2012

We investigated the mechanisms involved in KHG26377 regulation of glutamate dehydrogenase (GDH) activity, focusing on the roles of SIRT4 and SIRT3. Intraperitoneal injection of mice with KHG26377 reduced GDH activity with concomitant repression of glucose-induced insulin secretion. Consistent with their known functions, SIRT4 ribosylated GDH and reduced its activity, and SIRT3 deacetylated GDH, increasing its activity. However, KHG26377 did not affect SIRT4-mediated ADP-ribosylation/inhibition or SIRT3-mediated deacetylation/activation of GDH. KHG26377 had no effect on SIRT4 protein levels, and did not alter total GDH, acetylated GDH, or SIRT3 protein levels in pancreatic mitochondrial lysates. These results suggest that the mechanism by which KHG26377 inhibits GDH activity and insulin secretion does not involve ADP-ribosylation of GDH by SIRT4 or deacetylation of GDH by SIRT3.

• 한국의류산업학회지
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• 제8권4호
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• pp.458-464
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• 2006

The adsorption ability of heavy metal ions from the aqueous solution by chitosan, which it is well known natural biopolymer, has been investigated. The fundamental study in this research is focusing on the physicochemical adsorption utilizing the chitosan as a organic chelating adsorbent, adsorb especially heavy metal ions from the waste liquid solution. The adsorption ability of the chitosan between metal ions, having different characteristics with Mw of 188,600, 297,200, and 504,200 g/mol and degree of deacetylation (DD) of 86.92% and 100% were investigated targeting on the $Ni^{2+}$, $Co^{2+}$, $Zn^{2+}$, and $Pb^{2+}$ ions, respectively. The uptake of heavy metal ions with chitosan was performed by atomic absorption flame emission spectrophotometer (AAS) as conducted residual metal ions. It was found that chitosan has an strong adsorption capacity for some metals under certain conditions. Chitosan, which have 100% degree of deacetylation showed high adsorption recovery ratio and have an affinity for all kinds of heavy metals. In contrast, the molecular weight of chitosan was not completely affected on metal ion adsorption.

• BMB Reports
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• 제50권4호
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• pp.162-163
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• 2017

RNA polymerase II-interacting the Set2 methyltransferase co-transcriptionally methylates histone H3 at lysine 36 within the body of genes. This modification facilitates histone deacetylation by Rpd3S HDAC in 3' transcribed regions to suppress cryptic initiation and slow elongation. Although this pathway is important for global deacetylation, no strong effects have been seen on genome-wide transcription under optimized laboratory conditions. In contrast, this pathway slows the kinetics of mRNA induction when target genes are induced upon environmental changes. Interestingly, a majority of Set2-repressed genes are overlapped by a lncRNA transcription that targets H3K36 methylation and deacetylation by Rpd3S HDAC to mRNA promoters. Furthermore, this pathway delays the induction of many cryptic transcripts upon environmental changes. Therefore, the Set2-Rpd3S HDAC pathway functions to fine-tune expression dynamics of mRNAs and ncRNAs.

• 한국의류산업학회지
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• 제5권1호
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• pp.71-76
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• 2003

Three different types of chitosan were prepared from red crab shells to study anti-microbial activity of chitosan on pathogenic bacteria, MRSA(Methicillin-resistant. Staphylococcus aureus), Water-insoluble chitosan, whose degree of deacetylation is kept over 90% and molecular weights are 20,000, 500,000, 150,000, 80,000, and 40,000, respectively. Water-soluble chitosan, whose degree of deacetylation is about 48% and molecular weights are 200,000 and 80,000. Water-soluble chitosan, whose degree of deacetylation is 82% and molecular weight is 3,900. The anti-microbial activities of three types of chitosan were investigated by Tube Dilution Technique(TDT) and Agar Plate Smear Method(APSM). And the following conclusions are made ; Chitosan having 5 different types of M.W chitosan (over 90% deacetylation) showed similar anti-microbial activities at over 0.05% concentration. Especially, chitosan having M.W 40,000 150,000 showed the excellent anti-microbial activity. The anti-microbial activity of chitosan was enhanced when the chitosan/acetic add solution was aged for 7days. The anti-microbial activity of chitosan was only shown at chitosan/acetic acid solution. The anti-microbial activity was not detected in chitosan solution dissolved in neutral pH water. Therefore, it can be concluded that the anti-microbial activity was due to NH3+ cationic ion of chitosan in acidic aqueous solution.

• 한국재료학회지
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• 제34권2호
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• pp.85-94
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• 2024

The optimization of deacetylation process parameters for producing chitosan from isolated chitin shrimp shell waste was investigated using response surface methodology with central composite design (RSM-CCD). Three independent variables viz, NaOH concentration (X₁), radiation power (X₂), and reaction time (X₃) were examined to determine their respective effects on the degree of deacetylation (DD). The DD of chitosan was also calculated using the baseline approach of the Fourier Transform Infrared (FTIR) spectra of the yields. RSM-CCD analysis showed that the optimal chitosan DD value of 96.45 % was obtained at an optimized condition of 63.41 % (w/v) NaOH concentration, 227.28 W radiation power, and 3.34 min deacetylation reaction. The DD was strongly controlled by NaOH concentration, irradiation power, and reaction duration. The coefficients of correlation were 0.257, 0.680, and 0.390, respectively. Because the procedure used microwave radiation absorption, radiation power had a substantial correlation of 0.600~0.800 compared to the two low variables, which were 0.200~0.400. This independently predicted robust quadratic model interaction has been validated for predicting the DD of chitin.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.26-31
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• 1999

The advantages of the organism Streptomycs griseus HUT 6037 is that the chitinase and chitosanase using chitinaceouse substrate are capable of hydrolyzing both amorphous and crystalline chitin and chitosan. We attempted to investigate the optimization of induction protocol for high-level production and secretion of chitosanase and the influence of chitin and partially deacetylated chitosan sources (75∼99% deacetylation). The maximum specific activity or chitinase has been found at 5 days cultivation with the 48 hours induction time using colloidal chitin as a carbon source. To investigate characteristic of chitosan activity according to substrate, we used chitosan with various degree of deacetylation as a carbon source and found that this strain accumulates chitosanase in the culture medium using chitosanaceous substrates rather than chitinaceous substrates. The highest chitosanase activity was also presented on 4 days with 99% deacetylated chitosan. The partially 53% deacetylated chitosan can secrete both chitinase and chitosanase which was defined as a soluble chitosan. The specific activities of chitinase and chitosanase were 0.89 at 3 days and 1.33 U/mg protein at 5 days, respectively. It indicate that chitosanase obtained from S. griseus HUT 6037 can hydrolyze GlcNAc-GlcN and GlcN-GlcN linkages by exo-splitting manner. This activity increased with increasing degree of deacetylation of chitosan. It is the first attempted to investigate the effects of chitosanase on various degrees of deacetylations of chitosan by S. griseus HUT 6037. The highest specific activity of chitosanase was obtained with 99% deacetylated chitosan.