多肽修饰的纳米金加速油-水界面酶促反应

Peptide Functionalized Gold Nanoparticle for Facilation of Enzymatic Reaction at Oil-Water Interface

用固相合成法制备阳离子氨基酸组成的多肽,再将其连接到巯基化合物上,用于纳米金表面配体交换,制备阳离子多肽修饰的纳米金,并研究了这种纳米粒子对油-水(O/W)乳液界面酶促反应速度的影响。结果发现,将含有荧光底物的乳滴同酶直接混合时,45min内溶液中未检测到荧光信号变化,但向该溶液中加入纳米粒子后溶液中荧光信号立即增强。出现该现象的主要原因是,当乳液界面酶促反应体系中含有纳米粒子时,纳米粒子表面的阳离子多肽同时吸附带负电荷的酶和乳液,迅速屏蔽酶与乳液之间的电荷排斥,使酶与乳液中的底物能有效接触,加速酶促反应进行;通过选用不同的油相制备乳液,调控纳米粒子与乳液之间的氢键作用,还可使酶促反应速度进一步提高。

Cationic peptide composed of positively charged amino acids was synthesized by solid phase method and conjugated to thiolated compound.Gold nanoparticle was functionalized with the synthesized peptide ligand using place-exchange reaction.The effect of the peptide functionalized gold nanoparticle on the lipase catalyzed hydrolysis of hydrophobic ester substrate at O/W emulsion interface was investigated.The fluorescent substrate contained oil was emulsified in buffer and mixed with enzyme.The results indicated that the fluorescence kept unchanged within 45 min.However,the fluorescence immediately increased after adding nanoparticles,which indicated that the enzymatic reaction speed at O/W emulsion interface was significantly increased in the presence of peptide modified gold nanoparticles.The reason for the enzymatic reaction speed increase was supposed to be the conjugation of both emulsion and enzyme to the nanoparticles,which screened the charge repulsion between the emulsion and enzyme.Furthermore,the enzymatic reaction at O/W emulsion interface could be controlled by using oil with different hydrogen bonding ability.