有機修飾矽烷對仿生矽包覆D型胺基酸氧化酶之影響

Effects of organically modified silanes on D-amino acid oxidase encapsulated in biomimetic silica.

莊喬安(Chiao-An Chuang)

指導教授 ： 游吉陽

大同大學/工程學院/生物工程學系所/碩士(2011年)

摘要

本論文係利用polyallylamine hydrochloride (PAA)或R5 peptide催化矽酸包覆Rhodosporidum toruloide D型胺基酸氧化酶(RtDAO)與磁性奈米粒子，並藉由tetramethoxysilane (TMOS)與不同比例之有機修飾矽烷混合，來探討包覆過程中，矽酸組成對包覆相RtDAO之影響。以PAA催化時，TMOS混合15% (mol/mol) trimethylmethoxysilane及30% (mol/mol) n-propyltrimethoxysilane (n-PTMS)，比活性提升40%及143%；而在R5 peptide催化時，其比活性提升376%及183%。於溫度耐受性方面，PAA催化時，其TM值皆上升，特別是混合30% (mol/mol) n-PTMS由液相之44.6℃增加至65.6℃；反觀，R5 peptide催化之組別，其TM值則沒有顯著之改善。於H2O2耐受性，PAA催化之包覆相RtDAO，其半衰期皆有延長，特別是混合30% (mol/mol) n-PTMS由液相的24.2 min增加為180 min；而R5 peptide催化之包覆相RtDAO，對H2O2耐受性的提升又較PAA催化時更為顯著，其半衰期皆超過180 min。PAA或R5 peptide催化之包覆相RtDAO，相較於液相酵素，對D-Leu及D-Met之受質專一性明顯提升。於重覆使用性中，以PAA催化之包覆相RtDAO，無論有無添加有機修飾矽烷，在重複使用6次後，殘餘活性仍有80%以上。

關鍵字

活性 ； 仿生矽 ； D型胺基酸氧化酶 ； 有機修飾矽烷 ； 穩定性

並列摘要

D-amino acid oxidase from Rhodosporidium toruloides (RtDAO) and magnetic nanoparticles were encapsulated within biomimetic silica, which was mediated by polyallylamine hydrochloride (PAA) or R5 peptide. The effects of silicic acid composition, which was adjusted by mixing tetramethoxysilane (TMOS) with modified silanes at different molar ratios, on the properties of encapsulated RtDAO were studied. When catalyzed by PAA, the specific activities of encapsulated RtDAO were increased by 40% and 143% when 15% (mol/mol) trimethylmethoxysilane and 30% (mol/mol) n-propyltrimethoxysilane (n-PTMS) were added, respectively; 376% and 183% increase were observed while catalyzed by R5 peptide. In thermal stability, when PAA was used, the TM values were all increased after encapsulation; largest improvement from 44.6℃ of the free RtDAO to 65.6℃ was achieved when 30% (mol/mol) n-PTMS was added. In contrast, there was no significant improvement in the case of R5 peptide. In oxidative stability, the half-lives were all increased when PAA was used; in particular, an 8-fold increase in half-life was observed when 30% (mol/mol) n-PTMS was included. The enhancement in oxidative stability was even more pronounced when R5 peptide was employed; the half-lives were longer than the experimental period of 180 min. Encapsulated RtDAO, comparing to free enzyme, showed greater specificity towards D-Met and D-Leu. In reusability study, encapsulated RtDAO catalyzed by PAA could be reused for 6 times and maintained over 80% of its initial activity.

並列關鍵字

activity ； biomimetic silica ； D-amino acid oxidase ； organically modified silanes ； stability

參考文獻

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