• 유기물자원화
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• 제19권2호
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• pp.16-21
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• 2011

생물흡착제는 그 자체만으로 실제폐수처리에 적용하기에는 충분하지 못한 구조를 가지고 있기 때문에 고정화는 매우 중요하다. 그래서 최근의 연구는 생물흡착제를 효과적으로 고정화시키는 방법에 초점이 맞추어져 있다. 미생물이나 다당류와 같은 생물흡착제의 기계적 강도를 향상시키기 위하여 지금까지 많은 고정화 방법이 제안되어 왔다. 본 연구에서는 다양한 고정화 방법들(adsorption, covalent binding, entrapment, encapsulation, and crosslinking)을 소개하고자 한다.

• 한국식품과학회지
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• 제29권2호
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• pp.320-325
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• 1997

이소말토올리고당의 생산에 사용되는 Aspergillus niger 유래의 TG의 고정화를 위해 여러가지 방법을 비교하여 고정화방법을 선정하였다. 이온결합과 흡착, entrapment, 공유결합과 금속이온을 이용한 결합 등을 이용하여 TG의 고정화를 시도하였다. TG의 고정화를 위해서는 수율면에서 우수하고(61.3%) 간편성도 있는 CNBr-activated sepharose 4B를 이용한 고정화 방법을 선정하였다. DEAE-sephadex를 이용한 이온결합에 의해서는 33.1%, Diaion HP-20를 이용한 흡착법에 의해서는 22.5%의 수율을 보였으나 CNBr-activated sepharose 4B를 이용한 고정화 방법에 비해 수율과 안정성이 낮아 제외하였다. Entrapment에 의한 고정화는 bead내의 확산저항으로 인해 최종산물의 생성에 불리한 것으로 판단되었고 magnesium silicate, silica gel, glass bead 등의 담체를 이용한 고정화방법은 낮은 수율로 인해, 금속이온을 이용한 경우 역시 낮은 수율과 장시간의 준비로 인해 고정화방법으로 부적당하다고 판단되었다.

• Journal of the Korean Wood Science and Technology
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• 제29권3호
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• pp.104-111
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• 2001

There are some evidence that active enzymatic proteins, e.g. fungal laccase, exist in the naturally occured soil humus. This study was performed to investigate the covalent binding of fungal laccase to the humic acid-iron complex, and to measure laccase activity of immobilized ones. Seven methods were adopted to form the covalent binding of fungal laccase with soil humic acids complexed with iron. Using these seven methods it was possible to change the dimension of spacer arm between laccase and support, and also to regulate the mode of covalent binding of this enzyme. The spacer arm was regulated from 2C to 11C. There was not observed any straight relationship between the spacer arm longitude and the laccase activity after immobilization, but the binding mode more effective than the former. Three out of the seven methods gave the high activity of immobilized laccase, and which active products of laccase immobilization was stable up to 10 days after the process. It is indicated that natural soil condition might be prevented the laccase activation by the toxic influence of some phenolic humic compounds. It was shown, for the first time, the possibilities to obtain the high activity of fungal laccase by binding to humic acids, and especially in complex with iron.

• Bulletin of the Korean Chemical Society
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• 제28권5호
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• pp.883-886
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• 2007

• Journal of Microbiology and Biotechnology
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• 제29권4호
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• pp.607-616
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• 2019

In this study, functionalized poplar powder (FPP) was used as a support material for the immobilization of enoate reductase (ER) and glucose-6-phosphate dehydrogenase (GDH) by covalent binding. Under optimal conditions, the immobilization efficiency of ER-FPP and GDH-FPP was 95.1% and 84.7%, and the activity recovery of ER and GDH was 47.5% and 37.8%, respectively. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis indicated that FPP was a suitable carrier for enzyme immobilization. ER-FPP and GDH-FPP exhibit excellent thermal stabilities and superior reusability. Especially, ER-FPP and GDH-FPP enable the continuous conversion of 4-(4-Methoxyphenyl)-3-buten-2-one with $NAD^+$ recycling. While the immobilization strategies established here were simple and inexpensive, they exploited a new method for the immobilization and application of ER and its cofactor recycling system.

• Journal of Electrochemical Science and Technology
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• 제5권1호
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• pp.19-22
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• 2014

Here we report a highly sensitive and stable detection of $NAD^+$ and NADH by the electrode on which diaphorase (DI) is covalently immobilized in viologen polymer network. The network is prepared by the covalent formation of the structure by mixing propylamine viologen (PAV), poly(ethylene glycol)(400) diglycidyl ether (PEGDGE), an diaphorase (DI). The PAV/PEGDGE/DI modified electrode has the sensitivity of $0.02nA{\cdot}{\mu}M$ and the detection limit of $3{\mu}M$ with a response time of 2 s ($t_{90%}$) for NADH sensing.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2181-2186
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• 2012

Dendrimers are a novel class of nonlinear polymers and due to their extensive applications in different fields, called versatile polymers. Polyamidoamine (PAMAM) dendrimers are one of the most important dendrimers that have many applications in nanobiotechnology and industry. Generally aldehyde terminated dendrimers are prepared by activation of amine terminated dendrimers by glutaraldehyde which has two problems, toxicity and possibility of crosslink formation. In this study, novel aldehyde-terminated PAMAM dendrimer was prepared and used for covalent immobilization of trypsin by the aim of finding a special reagent which can prevent crosslinking and deactivation of the enzyme. For this purpose aminoacetaldehydedimethylacetal (AADA) was used as spacer group between aldehyde-terminated PAMAM and trypsin.The findings of this study showed that immobilization of trypsin not only resulted higher optimal temperature, but also increased the thermal stability of the immobilized enzyme in comparison to the free enzyme.

• Journal of Microbiology and Biotechnology
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• 제22권5호
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• pp.628-636
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• 2012

Raw-starch-digesting enzyme (RSDA) was immobilized on Amberlite beads by conjugation of glutaraldehyde/polyglutaraldehyde (PG)-activated beads or by crosslinking. The effect of immobilization on enzyme stability and catalytic efficiency was evaluated. Immobilization conditions greatly influenced the immobilization efficiency. Optimum pH values shifted from pH 5 to 6 for spontaneous crosslinking and sequential crosslinking, to pH 6-8 for RSDA covalently attached on polyglutaraldehyde-activated Amberlite beads, and to pH 7 for RSDA on glutaraldehyde-activated Amberlite. RSDA on glutaraldehyde-activated Amberlite beads had no loss of activity after 2 h storage at pH 9; enzyme on PG-activated beads lost 9%, whereas soluble enzyme lost 65% of its initial activity. Soluble enzyme lost 50% initial activity after 3 h incubation at $60^{\circ}C$, whereas glutaraldehyde-activated derivative lost only 7.7% initial activity. RSDA derivatives retained over 90% activity after 10 batch reuse at $40^{\circ}C$. The apparent $K_m$ of the enzyme reduced from 0.35 mg/ml to 0.32 mg/ml for RSDA on glutaraldehyde-activated RSDA but increased to 0.42 mg/ml for the PG-activated RSDA derivative. Covalent immobilization on glutaraldehyde Amberlite beads was most stable and promises to address the instability and contamination issues that impede the industrial use of RSDAs. Moreover, the cheap, porous, and non-toxic nature of Amberlite, ease of immobilization, and high yield make it more interesting for the immobilization of this enzyme.

• KSBB Journal
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• 제18권4호
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• pp.306-311
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• 2003

융합단백질의 절단을 위해 EK를 고정화하여 액상 절단반응과 같은 80％의 절단수율을 얻을 수 있었다. 그리고 니켈 친화칼럼을 이용하여 간단한 정제공정을 구축하였다. 공유결합한 EK의 경우 니켈친화 결합한 EK보다 높은 재접힘 수율을 나타내었고 풀림과 재접힘을 이용하여 효소의 초기 활성을 회복함에 따라서 반복사용을 통한 경제적인 절단공정을 구축할 수 있게 되었다. 그러나 고정화 과정에서 효소의 활성이 감소하는 문제점과 고정화 수율을 높이기 위한 연구가 필요하다.

• Journal of Microbiology and Biotechnology
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• 제1권1호
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• pp.54-62
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• 1991

Cyclodextrin glucanotransferase(CGTase) derived from Bacillus macerans was immobilized by (1) covalent linkage on chitosan and chitin with glutaraldehyde, (2) adsorption on DEAE-cellulose and Amberite IRA 900 after succinylation, and (3) entrapment on alginate and polyacrylamide by cross linking. Adsorption on Amberite IRA 900 and covalent linking on chitosan were identified to be the most suitable immobilization methods considering the yield of activity and stability of immobilized CGTase. The enzymatic properties of immobilized CGTase were investigated and compared with those of the soluble CGTase. Thermal stability of CGTase immobilized on chitosan was increased from 50 to $55^{\circ}C$, and the optimum temperature of CGTase immobilized on Amberite IRA 900 was shifted from 55 to $50^{\circ}C$. The effect of molecular size of soluble starch (substrate) on immobilized CGTase investigated using partially liquefied substrates with different dextrose equivalent(DE). Cyclodextrin(CD) conversion yield augmented according to the increase of DE level for immobilized CGTase on Amberite IRA 900. CD conversion yield of partially cyclized starch with soluble CGTase was higher compared with liquefied one with ${\alpha}-amylase$.