• Asian-Australasian Journal of Animal Sciences
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• 제12권3호
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• pp.411-416
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• 1999

Ninety-six, 35 day old, crossbred pigs, were fed either a basal diet based on com, soybean meal, fish meal and whey or one of three similar diets supplemented with either 0.5% organic acid or enzyme both alone and in combination. Neither organic acid nor enzyme produced any significant (p<0.05) improvements in daily gain or feed conversion. Organic acid, both alone and in combination with enzyme, significantly (p=0.04) decreased the pH in the lower colon. None of the treatments produced any effects on E. Coli or Lactobacillus numbers in any part of the gastrointestinal tract. Feeding enzyme increased trypsin (p=0.01), chymotrypsin (p=0.03) and amylase (p=0.08) levels in the jejunum. Chymotrypsin levels were higher (p=0.04) in the ileum of pigs fed enzyme. Serum glucose levels were lower (p=0.01) on day 14 in pigs fed enzyme either alone or in combination with acid. Under the conditions of this experiment (10% dietary whey, pigs weaned at 35 days of age), neither organic acid nor enzyme were effective in improving starter pig performance. Therefore, there would appear to be little justification for the routine inclusion of these products in diets fed to pigs weaned at 35 days or later.

• Journal of Animal Science and Technology
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• 제63권1호
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• pp.69-76
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• 2021

This experiment was conducted to evaluate the effect of supplementing enzyme cocktail on growth performance, digestibility of nutrients, and monosaccharide concentration in ileum and ceca of broiler chickens fed wheat-based diets. A total of 600 male broilers (42.26 ± 1.76 g, 0 day old) were used for 35 days of feeding trial consisting of 2 phases (starter phase from d 0 to 21 and finisher phase from d 21 to 35). Four dietary treatments were prepared based on wheat diets containing four levels of enzyme cocktail supplementation at 0, 0.2, 0.3, and 20 g/kg. Overall, dietary enzyme cocktail supplementation decreased feed conversion ratio (linear p = 0.007; quadratic p = 0.013) and improved (linear p < 0.05) the apparent ileal digestibility of dry matter (DM), crude protein, and soluble and insoluble non-starch polysaccharides. The apparent total tract digestibility of DM and gross energy were increased (linear p < 0.01) with increasing supplementation levels of the dietary enzyme cocktail. The concentrations of arabinose, xylose, mannose, and glucose in ileal digesta were linearly increased (p < 0.01) with increasing enzyme cocktail supplementation levels. In addition, the quadratic effect was observed (quadratic p = 0.046) in mannose concentration of ileal digesta. The concentration of arabinose, xylose, mannose, and galactose in cecal digesta was increased (linear p < 0.05) with increasing dietary enzyme cocktail supplementation levels. The supplementation of enzyme cocktail efficiently increased the utilization of nutrients in broiler and there was no adverse effects of high dosage supplementation level.

• Journal of Microbiology and Biotechnology
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• 제4권3호
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• pp.204-209
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• 1994

The synthesis of N-(benzyloxycarbonyl)-L-aspartyl-L-phenylalanine methylester (Z-APM), a precursor of aspartame, from N-(benzyloxycarbonyl)-L-aspartic acid (Z-Asp) and L-phenylalanine methylester hydrochlolide($L-PM\cdot HCI$) was investigated in a saturated-ethylacetate single phase system using immobilized thermolysin. Among the various supports tested, glyceryl-CPG was found to be most efficient for retaining enzyme activity. The enzyme immobilized onto glyceryl-CPG also showed the highest activity for Z-APM synthesis in saturated ethyl acetate. Z-APM conversion yield in saturated ethylacetate was half of that obtained in an ethyl acetate-buffer two-phase system under the same reaction conditions. However, as the mole ratio of $L-PM \cdot HCI$ to Z-Asp was increased to 4.0, the conversion yield reached 95 %. When continuous synthesis of Z-APM was canied out in a plug flow reactor (PFR) with 80 mM of L-PMㆍHCI and 20 mM of Z-Asp in saturated ethylacetate (pH 5.5), more than 95 % of Z-Asp was converted to Z-APM with a space velocity of 1.16 $hr^{-1} at 40^{\circ}C$. Although the operational stability in PFR was reduced rapidly, more than 80% of initial activity was maintained in CSTR even after a week of operation.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.511-516
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• 2005

Sorbitan methacrylate was synthesized from sorbitan dehydrated from D-sorbitol using an immobilized lipase. To optimize the enzymatic synthesis of sorbitan methacrylate, response surface methodology was applied to determine the effects of five-level-four-factors and their reciprocal interactions on sorbitan methacrylate biosynthesis. A total of 30 individual experiments were performed, which were designed to study reaction temperature, reaction time, enzyme amount and substrate molar ratio. A statistical model predicted that the highest conversion yield of sorbitan methacrylate was 100%, at the following optimized reaction conditions: a reaction temperature of 43.06 $^{\circ}C$, a reaction time of 164.25 mins., an enzyme amount of 7.47%, and a substrate molar ratio of 3.98:1. Using these optimal factor values under experimental conditions in four independent replicates, the average conversion yield reached 98.7%${\pm}$1.2% and was well within the value predicted by the model.

• 미생물학회지
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• 제37권2호
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• pp.164-169
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• 2001

Cephamycin C를 생산하는 몇가지 균주를 사용하여 cephalosporin C로부터 7$\alpha$-hydroxycephalosporin C로의 전환력을 조사하였다. 이들 균주중에서 cephalosporin 7$\alpha$-hydroxylase의 활성은 Streptomyces clavuligerus ATCC 27064가 가장 높게 나타났다. Streptomyces clavuligerus ATCC 27064로부터 얻은 조효소액을 정제한 후 activated DEAE-sphacel 레진에 고정화하여 기질인 cephalosporin C로부터 7$\alpha$-hydroxycephalosporin C를 생산하였다. 고정화에 의해서 생성된 물질을 ESI-Mass로 측정한 결과, 분자량 431로 나타났다. 또한 $^1H$ NMR 분석에 의해 고정화 효소에 의해 생성된 물질은 cephalosporin C로부터 얻어진 7$\alpha$-hydroxycephalosporin C임을 확인하였다.

• 대한화장품학회지
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• 제46권4호
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• pp.349-360
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• 2020

최근 피부 기능 개선과 관련한 다양한 가능성으로 인해 화장품 소재로서 수요가 높아지고 있는 인삼 유래 사포닌의 한 종류인 ginsenoside Rd를 위한 생물 전환 제조 기술을 확립하였다. 홍삼 사포닌(RGS)에 포함된 ginsenoside Rb1을 Rd로 전환하기 위하여 상업용 효소를 탐색하였고 그 중 Viscoflow MG가 가장 효율적인 것을 확인하였다. Ginsenoside Rd로의 전환에 영향을 주는 요인을 최적화하기 위하여 반응표면분석법(RSM)을 통하여 실험 조건을 설계하였다. 주요 독립변수는 RGS 농도, 효소 농도와 반응 시간이었고 Box-Behnken design (BBD) 모델설계법에 따라 선정된 17 가지 조건으로 ginsenoside Rd로 전환을 수행하고 최적화 조건을 분석하였다. 전환된 Ginsenoside Rd의 농도는 0.3113 g/L에서 최대 0.5277 g/L까지였고 RGS 2%, 효소 1.25%를 13.5 h 반응시킨 조건에서 가장 높은 생성량을 보였다. 결론적으로, ginsenoside Rd 생물전환의 독립변수인 RGS 농도, 효소 농도는 p-value가 0.05보다 작은 값으로 유의미한 값을 나타내었고 각 독립변수 사이의 교호작용 중에서는 효소 농도와 반응 시간 사이의 교호 작용이 가장 큰 영향력을 갖고 있음을 확인하였다.

• KSBB Journal
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• 제11권6호
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• pp.712-717
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• 1996

셀룰라아제, polyoxyethylene 유도체와 maleic acid anhydride의 공중합고분자로 중합한 수식셀룰 라아제를 제조하고, 당화 특성과 효소 반응 속도론 등을 검토하였다. 수식 반응에서, 공중합고분자-효소 질량비가 증가함에 따라 수식률은 증가하며, 질량비 4 이상에서는 수식률이 일정하였다. 이 때 최 대수식률은 55% 이며 최대수식률의 수식생룰라아제 는 75%의 높은 효소활성을 나타내었다. 수식효소와 미수식효소의 당화 실험에서, 수식효소가 전 반응시 간에 걸쳐 미수식효소보다 높은 당화반응안정성을 유지하였으며, 그로 인해 최종 전화율은 수식효소가 더 큰 값을 가졌다. 기질에의 강한 흡착으로 인한 효소 deactivation을 고려한 반응식을 적용한 결과, 생 성환원탕놓도의 실험값과 계산치는 잘 일치하였다. 그로부터 반응속도상수를 구하고 생성환원당농도와 유리효소농도의 모사그래프를 구할 수 있었으며, 반 응시간에 따른 유리효소의 농도를 수치모사한 결과, 미수식효소에 비해 수식효소의 유리효소 농도가 더 높았고 그로 인해 더 높은 당전화율을 나타내였다.

• 분석과학
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• 제10권1호
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• pp.66-74
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• 1997

지름 2.54cm, 길이 10cm인 유리관에 tyrosinase(EC. 1.14.18.1)를 입자의 크기 $550{\mu}m$인 탄소에 고정시켜 충진하고, 페놀과 산소를 기질로 사용하여 tyrosinase의 반응 특성을 조사하기 위해 axial dispersion 모델을 제안하였다. 본 논문에서 페놀의 농도는 55.5mM로 고정시키고 산소(2.7ppm, 5.4ppm, 그리고 9.5ppm)와 유속 (1~3mL/s)을 변화시키면서 탄소에 고정된 tyrosinase의 반응을 관찰하였다. 또한, Damkolher수를 계산하고 분산 특성과 식으로부터 효소반응 속도 및 분산의 영향을 예측하기 위해 수치적 해석을 하였다. 연구 결과 물질저항은 주로 외부 전달과 내부확산이었으며, 제안된 모델에서 Biot수는 64.25였다. 페놀은 1.0mL/s 정도의 느린 속도에서 산소의 농도가 높을수록 높은 전환율을 나타내었다. 한편, axial dispersion 모델과 plug flow 모델의 비교에서는 모두 같은 전환율을 나타내어 axial dispersion 모델이 반응속도와 무관함을 알 수 있었다.

• Molecules and Cells
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• 제37권4호
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• pp.322-329
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• 2014

N-acetylglucosamine kinase (GlcNAc kinase or NAGK; EC 2.7.1.59) is highly expressed and plays a critical role in the development of dendrites in brain neurons. In this study, the authors conducted structure-function analysis to verify the previously proposed 3D model structure of GlcNAc/ATP-bound NAGK. Three point NAGK mutants with different substrate binding capacities and reaction velocities were produced. Wild-type (WT) NAGK showed strong substrate preference for GlcNAc. Conversion of Cys143, which does not make direct hydrogen bonds with GlcNAc, to Ser (i.e., C143S) had the least affect on the enzymatic activity of NAGK. Conversion of Asn36, which plays a role in domain closure by making a hydrogen bond with GlcNAc, to Ala (i.e., N36A) mildly reduced NAGK enzyme activity. Conversion of Asp107, which makes hydrogen bonds with GlcNAc and would act as a proton acceptor during nucleophilic attack on the ${\gamma}$-phosphate of ATP, to Ala (i.e., D107A), caused a total loss in enzyme activity. The overexpression of EGFP-tagged WT or any of the mutant NAGKs in rat hippocampal neurons (DIV 5-9) increased dendritic architectural complexity. Finally, the overexpression of the small, but not of the large, domain of NAGK resulted in dendrite degeneration. Our data show the effect of structure on the functional aspects of NAGK, and in particular, that the small domain of NAGK, and not its NAGK kinase activity, plays a critical role in the upregulation of dendritogenesis.

• Journal of Microbiology and Biotechnology
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• 제13권4호
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• pp.501-508
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• 2003

Artificial coupling of one enzyme with another can provide an efficient means for the production of industrially important chemicals. Xylose reductase has been recently discovered to be useful in the reductive production of xylitol. However, a limitation of its in vitro or in vivo use is the regeneration of the cofactor NAD(P)H in the enzyme activity. In the present study, an efficient process for the production of xylitol from D-xylose was established by coupling two enzymes. A NADH-dependent xylose reductase (XR) from Pichia stipitis catalyzed the reduction of xylose with a stoichiometric consumption of NADH, and the resulting cofactor $NAD^+$ was continuously re-reduced by formate dehydrogenase (FDH) for regeneration. Using simple kinetic analyses as tools for process optimization, suitable conditions for the performance and yield of the coupled reaction were established. The optimal reaction temperature and pH were determined to be about $30^{\circ}C$ and 7.0, respectively. Formate, as a substrate of FDH, affected the yield and cofactor regeneration, and was, therefore, adjusted to a concentration of 20 mM. When the total activity of FDH was about 1.8-fold higher than that of XR, the performance was better than that by any other activity ratios. As expected, there were no distinct differences in the conversion yields of reactions, when supplied with the oxidized form $NAD^+$ instead of the reduced form NADH, as a starting cofactor for regeneration. Under these conditions, a complete conversion (>99%) could be readily obtained from a small-scale batch reaction.