Zefen Wang,Qian Zhou,Siyuan Liu,Dankui Liao,Pengru Liu,Xiongdiao Lan
Immobilized angiotensin-converting enzyme (ACE) is a promising material for the rapid screening of antihypertensive drugs, but the nonspecific adsorption is a serious problem in separation processes involving complex biological products. In this study, triblock copolymers with dopamine (DA) block as anchors and PEG block as the main body (DA-PEGx-DA) were attached to an immobilized ACE (ACE@mZIF-8/PDA, AmZP) surface via the “grafting to” strategy which endowed them with anti-nonspecific adsorption. The influence of DA-PEGx-DA chain length on nonspecific adsorption was confirmed. The excellent specificity and reusability of the obtained ACE@mZIF-8/PDA/DA-PEG5000-DA (AmZPP5000) was validated by screening two known ACE inhibitory peptides Val-Pro-Pro (VPP, competitive inhibitory peptides of ACE) and Gly-Met-Lys-Cys-Ala-Phe (GF-6, noncompetitive inhibitory peptides of ACE) from a mixture containing active and inactive compounds. These results demonstrate that anchored polymer loops are effective for high-recognition selectivity and AmZPP5000is a promising compound for the efficient separation of ACE inhibitors in biological samples.Keywords:polymer loops;angiotensin converting enzyme;immobilization of enzyme;mesoporous ZIF-8;recognition selectivity
Zefen Wang,Siyuan Liu,Qian Zhou,Pengru Liu,Dankui Liao,Ping Lan,Bo Peng,Xiongdiao Lan
Immobilized angiotensin converting enzyme (ACE) utilizes specific interaction between ACE and ACE inhibitors to screen drugs for hypertension therapy, but traditional immobilized ACE is insufficient to achieve satisfactory effect for the poor immobilization efficiency and stability. In this work, mesoporous ZIF-8 (mZIF-8) coated with polydopamine (PDA) was developed as an enzyme-immobilization platform for the first time. Molecular docking was used to study the mechanism of ACE induced mZIF-8 synthesis. The immobilized enzyme ACE@mZIF-8/PDA were shown to possess mesoporous structures with ACE encapsulation efficiency of ∼90%. Compared with the free enzyme, ACE@mZIF-8/PDA exhibited enhanced tolerance to temperature, pH, unfolding and proteolytic agents, with excellent reusability (maintained 82.29% ± 4.11% of initial activity after being reused 10 times) and storage stability (retaining 93.12% ± 3.271% residual activity after 30 days). Molecular docking research conformed ACE induced the triggered nucleation of MOFs via binding with MOFs precursors. Moreover, ACE@mZIF-8/PDA was used as high-performance adsorbent for enrichment of ACE inhibitory peptides. The noncompetitive inhibitory peptide GF-6 and competitive inhibitory peptide VPP could be captured synchronously, which avoided the loss of active substances. These results indicated that the ACE@mZIF-8/PDA provides an evolutionary platform for rapid screening of inhibitory peptides.
Yuxiao Feng,Yingjie Du,Geling Kuang,Le Zhong,Hongtong Hu,Shiru Jia,Jiandong Cui
Metal–organic frameworks (MOFs), with large specific surface area and tunable porosity, have gained lots of attention for immobilizing enzymes. However, the intrinsic open channels of most reported MOFs are generally smaller than 2 nm, which significantly prevents the passage of enzymes, and the diffusion efficiency of substrates and products. Here we report a new hierarchical micro-mesoporous zeolitic imidazolate framework-8 (ZIF-8) with core–shell superstructure (HZIF-8) using colloidal hydrated zinc sulfate (ZnSO 4 ·7H 2 O) as a soft template for enzyme immobilization. The ZnSO 4 ·7H 2 O forms an aggregation of colloids due to the self-conglobation effect in methanol, which affords a soft template for the formation of HZIF-8. Cytochrome C (Cyt C) was immobilized in interior of HZIF-8 through entrapment during the formation of HZIF-8. The resultant immobilized Cyt C (Cyt [email protected] ) exhibited 4-fold and 3-fold higher activity than free Cyt C and Cyt C encapsulated in conventional microporous ZIF-8 (Cyt [email protected] ), respectively. Meanwhile, the Km value of Cyt [email protected] significantly decreased due to the presence of mesopores compared with Cyt [email protected] , indicating enhanced substrate affinity. After 7 cycles, Cyt [email protected] still maintained 70% of its initial activity whereas Cyt [email protected] only retained 10% of its initial activity. Moreover, the obtained HZIF-8 showed outstanding performance in co-immobilization of multi-enzyme for the detection of glucose.
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