Ahmad Raneem, Rizaldo Sydnie, Gohari Mahnaz, Shanahan Jordan, Shaner Sarah E, Stone Kari L, Kissel Daniel S
Department of Chemistry, Lewis University, One University Pkwy, Romeoville, Illinois 60446, United States.
Department of Chemistry and Physics, Southeast Missouri State University, One University Plaza, Cape Girardeau, Missouri 63701, United States.
ACS Omega. 2023 Jun 9;8(25):22545-22555. doi: 10.1021/acsomega.3c00703. eCollection 2023 Jun 27.
Novel biocatalysts that feature enzymes immobilized onto solid supports have recently become a major research focus in an effort to create more sustainable and greener chemistries in catalysis. Many of these novel biocatalyst systems feature enzymes immobilized onto metal-organic frameworks (MOFs), which have been shown to increase enzyme activity, stability, and recyclability in industrial processes. While the strategies used for immobilizing enzymes onto MOFs can vary, the conditions always require a buffer to maintain the functionality of the enzymes during immobilization. This report brings attention to critical buffer effects important to consider when developing enzyme/MOF biocatalysts, specifically for buffering systems containing phosphate ions. A comparative analysis of different enzyme/MOF biocatalysts featuring horseradish peroxidase and/or glucose oxidase immobilized onto the MOFs UiO-66, UiO-66-NH, and UiO-67 using a noncoordinate buffering system (MOPSO buffer) and a phosphate buffering system (PBS) show that phosphate ions can have an inhibitory effect. Previous studies utilizing phosphate buffers for enzyme immobilization onto MOFs have shown Fourier transform infrared (FT-IR) spectra that have been assigned stretching frequencies associated with enzymes after immobilization. Analyses and characterizations using zeta potential measurements, scanning electron microscopy, Brunauer-Emmett-Teller surface area, powder X-ray diffraction, Energy Dispersive X-ray Spectroscopy, and FT-IR show concerning differences in enzyme loading and activity based on the buffering system used during immobilization.
以固定在固体载体上的酶为特征的新型生物催化剂，最近已成为一项主要研究重点，旨在创造更可持续、更环保的催化化学。这些新型生物催化剂系统中的许多都以固定在金属有机框架（MOF）上的酶为特征，在工业过程中，已证明这些酶能提高酶的活性、稳定性和可回收性。虽然将酶固定在MOF上所使用的策略可能各不相同，但这些条件始终需要一种缓冲剂，以在固定过程中维持酶的功能。本报告提请注意在开发酶/MOF生物催化剂时需要考虑的关键缓冲效应，特别是对于含有磷酸根离子的缓冲系统。使用非配位缓冲系统（MOPSO缓冲液）和磷酸盐缓冲系统（PBS），对固定在MOF UiO-66、UiO-66-NH和UiO-67上的辣根过氧化物酶和/或葡萄糖氧化酶的不同酶/MOF生物催化剂进行的比较分析表明，磷酸根离子可能具有抑制作用。先前利用磷酸盐缓冲液将酶固定在MOF上的研究显示，傅里叶变换红外（FT-IR）光谱显示了固定后与酶相关的拉伸频率。使用zeta电位测量、扫描电子显微镜、布鲁诺尔-埃米特-泰勒表面积、粉末X射线衍射、能量色散X射线光谱和FT-IR进行的分析和表征表明，基于固定过程中使用的缓冲系统，酶负载和活性存在令人担忧的差异。
