A putative maltogenic amylase gene (DGMA) was cloned from the Deinococcus geothermalis DSM 11300 genome using the polymerase chain reaction. The gene encoded 608 amino acids with a predicted molecular mass of 68,704 Da. The recombinant DGMA was constitutively expressed using the pHCXHD plasmid. As expected, the recombinant DGMA hydrolyzed cyclodextrins and starch to maltose and pullulan to panose by cleaving the α-(1,4)- glycosidic linkages, as observed for typical maltogenic amylases. Characterization of the recombinant DGMA revealed that the highest maltogenic amylase activity occurred at 40 ℃ and pH 6.0. The half-life of catalytic activity at 65 ℃ and 55 ℃ were 8.2 min and 187.4 min, respectively. DGMA mainly hydrolyzed β-cyclodextrin, soluble starch, and pullulan and its efficient ratio of those substrates was 9:4.5:1.
The capability of synthesizing polyphenol glycosides was examined using recombinant amylosucrase from the hyperthermophilic bacterium Deinococcus geothermalis. Based on the action mode of amylosucrase, sucrose and twenty-one polyphenols were used as a donor and acceptors respectively. The transglycosylation reaction by amylosucrase produced one or two major polyphenol glycosides depending on the type of polyphenols used. The synthesized polyphenol glycosides were detected by thin-layer chromatography. The structures of the newly synthesized polyphenol glycosides were predicted based on the transglycosylation mechanism of the enzyme. According to the acceptability of the polyphenols, the structural characteristics of polyphenol as an efficient acceptor were evaluated. The results indicate that amylosucrase is an efficient catalyst for the enzymatic synthesis of polyphenol glycosides, which have high potentials in food, cosmetics, and pharmaceutical industries.
감자의 전분 추출 효율을 증진시키기 위하여 cellulase 계열의 5종 식품용 효소제를 이용하여 감자 전분 추출 효율을 탐색하였다. 5종의 cellulase 효소 중 β-glucanase 계열의 효소인 Laminex®BG2는 다른 cellulase 효소제에 비하여 가격 경쟁력이 높고 감자 세포 내의 유세포 등을 파괴하여 입자가 작은 전분을 용출시켰으며, 전분의 추출 효율이 비 효소처리 공정보다 40% 증가됨을 확인되었다. Laminex®BG2를 이용하여 추출된 전분은 용출된 작은 입자의 영향으로 호화개시온도가 낮아진 것 이외에 화학적 특성은 거의 대부분 차이가 없는 것으로 나타났다. 따라서 감자 전분의 추출 시, 식품용 cellulase 효소인 Laminex®BG2를 이용하면 기존의 방법보다 추출 효율을 효과적으로 증진시킬 수 있을 것으로 기대된다.
Swollenin, a fungal protein, is presumed to disrupt hydrogen bonding between cell wall polysaccharides. Despite of the disruption of hydrogen bonding, the swollenin is known not to possess the hydrolytic activity against cellulose. Therefore, the swollenin is thought to play some roles other than hydrolysis of cellulose when the fungi attack the lignocellulose which is the main body of plant biomass. In this study, the gene encoding swollenin was cloned from Trichoderma reesei into Saccharomyces cerevisiae. The activity of the swollenin was then evaluated by quantifying how much the swollenin preparation assist the action of cellulose on the cellulose when the protein was incubated with cellulose and cellulase.
대두단백 필름을 코팅한 라이너지의 효과를 알아보기 위하여 대두단백 2~8%의 농도 범위에서 필름을 제조하였다. 필름 제조시 친수성 소재인 대두단백의 불용화를 위하여 모든 필름은 formaldehyde로 포화된 데시케이터에서 2시간 동안 흡착하여 사용하였다. 필름의 연신강도, 연신율, 투습도 및 수분용해도를 측정한 뒤 최적 농도를 5%로 판단하였다. 필름의 제조적성을 위해 첨가된 가소제 glycerol은 대두단백 대비 40% 농도에서 필름제조에 가장 적합하였다. 앞의 조건을 이용하여 제조된 용액을 라이너지에 코팅하여 그 물성과 수분저항성을 측정하였다. Formaldehyde 처리된 대두단백코팅 라이너지는 미처리 라이너지에 비하여 연신강도는 15에서 21㎫로 증가하였고, 수분용해도와 투습계수는 1.17%와 2.06 ngㆍm/㎡ㆍsㆍ㎩로 감소하여 물리적 성질과 수분저항성 모두 증진된 것을 알 수 있었다.
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