摘要
以3-氨丙基三乙氧基硅烷(APTES)对介孔二氧化钛晶须(MTiO2_ws)进行表面修饰,使其电荷零点值(pzc)由5.3提高至6.8,改性后材料MTiO2_ws-APTES的比表面积略有上升,但孔结构基本不变。以MTiO2_ws-APTES为载体对γ-谷氨酰转肽酶(GGT)进行了固定化,当给酶量小于150U.g-1时,酶活回收率均大于99%,固定化酶MTiO2_ws-APTES-GGT的比活力最高可达184.0U.g-1,对酶的负载性能显著优于MTiO2_ws。相比于游离酶,MTiO2_ws-APTES-GGT的最适温度和热稳定性均略有下降,但pH稳定性明显优于游离酶和以MTiO2_ws为载体的固定化酶(MTiO2_ws-GGT);MTiO2_ws-APTES-GGT对γ-谷氨酰对硝基苯胺(GpNA)的亲和力常数(Km)为0.889mmol·L-1,较游离酶有所上升,但小于MTiO2_ws-GGT。MTiO2_ws-APTES-GGT的稳定性良好,经4℃下储藏60d,连续使用21批次后残余酶活仍可达初始值的80.07%。
Mesoporous TiO2 whiskers (MTiO2 _ ws)were chemically modified with 3-aminopropyltriethyloxy silane (APTES). As a result, the point of zero charge (pzc) for the modified material (MTiO2 _ ws- APTES) rose from 5.3 to 6.8. Also the specific surface area of MTiO2 _ ws-APTES slightly increased, but the pore structure had little change compared to that of MTiO2 _ ws. Then, MTiO2 _ ws-APTES was used as the support for γ-glutamyltranspeptidase (GGT) immobilization. MTiO2 _ ws-APTES showed better loading capacity than MTiO2 _ ws. While the enzyme concentration was less than 150 U . g- 1, the recovery of activity was above 99% and the highest specific activity for immobilized GGT (MTiO2 _ ws APTES-GGT) was 184.0 U . g -1. Although both optimal temperature and thermal stability of MTiO2 _ws-APTES-GGT slightly decreased compared with the native enzyme, pH stability was greatly improved. The affinity constant (Kin) of MTiO2 _ ws-APTES-GGT toward γ-glutamyl-p-nitroaniline (GpNA) was also determined to be 0. 889 mmol . L -1, which was higher than that of the native enzyme, but less than that of MTiO2 _ ws-GGT. After storage at 4℃ for 60 days and reused for 21 batches, MTiO2 _ ws-APTES-GGT maintained 80.07% of its initial activity.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2013年第6期2160-2168,共9页
CIESC Journal
基金
江苏省高校自然科学研究重大基金项目(10KJA530014)
江苏省科技支撑计划(社会发展)基金项目(SBE 201078182)
江苏省自然科学基金项目(BK2011799
BK2012825)
关键词
介孔氧化钛晶须
化学改性
3-氨丙基三乙氧基硅烷
固定化酶
稳定性
担载量
mesoporous TiO2 whiskers
chemical modification
3-aminopropyltriethyloxy silane
enzyme immobilization
stability
loading capacity