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배 과육 조직의 불용성 펙틴의 조성과 효소에 의한 가수분해
김종기(Jongkee Kim),황병호(Byung Ho Hwang),차주형(Ju Hyoung Cha),홍지흔(Ji Heun Hong) 한국원예학회 2008 원예과학기술지 Vol.26 No.3
배 주스 착즙 후 여과 및 저장 중에 생성되는 불용성 펙틴을 분해하는 효소를 분리 동정하고자 본 실험은 수행되었다. ‘신고’ 배 과육 12㎏을 시판중인 pectinase를 처리한 후 용액속의 불용성 펙틴 6.53g을 회수하였다. 이 불용성 펙틴에는 rhamnose/galacturonic acid가 0.19로 rhamnosyl기의 비율이 높았으며, 및 mannose의 함량이 40%에 달하였다. Alginate affinity 칼럼을 사용하여 시판중인 pectinase(Pectinex Ultra SP-L)로부터 polygalcturonase(PG)를 효과적으로 제거하였다. PG가 제거된 Aspergillus pectinase는 불용성 펙틴을 분해하였으며, 분해된 산물은 naringinase의 α-rhamnosidase에 의해 terminal rhamnose를 가진 올리고 당으로 확인되었다. Aspergillus pectinase 에 의해 분해된 펙틴의 분자량의 감소를 gel permeation chromatography로 확인하였으며, 올리고당의 비율은 비교적 낮았다. In order to improve juice quality and filtration process of pear (Pyrus pyrifolia) pulp extracts, insoluble pectins were obtained from pear fruit after enzymatic hydrolysis of the pulp tissue with commercial pectinases. Compositional analysis revealed that the insoluble pectin has a high ratio in rhamnose to galacturonic acid, 0.19, which was a very similar to ‘modified hairy region’ of apple pectin. In addition, the pear pectin was also rich in glucose and mannose, comprising approximately 40% of the polymer. Enzyme (s) capable to degrade the insoluble pectins was isolated from a commercial Aspergillus pecteolytic enzyme preparations using an alginate affinity chromatography. Aspergillus polygalacturonase (PG) was tightly bound to the alginate resin at pH 4.0 and efficiently separated by raising the pH of the elution buffer into 8.0. Gel permeation chromatography of the hydrolysates of insoluble pectin by the enzyme fractions unbound to the alginate resin showed a molecular weight shift from a large to a smaller weight polymers. The enzyme product, insoluble by PG, was further incubated with a α-rhamnosidase of commercial naringinase to hydrolyse terminal rhamnose. An increase in soluble, monomeric rhamnose confirmed that the fungal pectinase had an activity of hydrolyzing rhamno-galacturonosyl backbone of pectin in pear fruit. From the results obtained, it was concluded that insoluble pectins from pear fruit juice was effectively degraded by a fungal pectinase, generating oligosaccharides rich in terminal rhamnose.