Understanding the Role of Surfactants in the Interaction and Hydrolysis of Myoglobin by Zr‐MOF‐808

Abstract

Controlled protein hydrolysis is an important procedure in proteomics applications and is used to aid the understanding of protein structure and function. The hydrolysis of hydrophobic proteins is particularly challenging, as due to their poor solubility the use of surfactants, which typically inactivate natural enzymes, is often required. Such limitations of natural enzymes prompted the development of chemical catalysts for the selective hydrolysis of proteins. In this study, the nanozymatic potential of MOF-808, a Zr 6 O 8 based metal organic framework, has been investigated towards protein hydrolysis in the presence of several surfactants which differ in structure and polarity. The influence of ionic SDS (sodium dodecyl sulfate), neutral TX-100 (Triton X-100) and zwitterionic Zw3-12 (ndodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate) and CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) surfactants on the hydrolysis of horse heart myoglo-bin in the presence of MOF-808 has been examined. The hydrolysis of horse heart myoglobin by MOF-808 was followed using sodium dodecyl sulfate poly(acrylamide) gel electrophoresis (SDS-PAGE), which showed that nanozymatic activity of MOF-808 can be tuned by using appropriate surfactants. To understand the observed reactivity patterns, the interactions between surfactant, MOF and protein were further investigated using a range of spectroscopic methods, which included Dynamic Light Scattering (DLS), 1 H NMR, UV-Vis, Circular Dichroism and UV-Vis Spectroscopy. While the presence of SDS increased the number of observed peptide fragments due to protein unfolding and increased protein-MOF interaction, the use of zwitterionic and neutral surfactant reduced the hydrolytic efficiency, most likely by hindering the efficient protein-MOF interaction.

Reactivity of metal–oxo clusters towards biomolecules: from discrete polyoxometalates to metal–organic frameworks

“…4.6, 13.7, 12.2, and 11.1 kDa (Table 7), with a hydrolysis efficiency of around 63% after 8 days in the absence of any surfactant. 270 However, addition of surfactants affects both the protein structure and the MOF-protein interactions in a rather complex manner and, therefore, the structure of the surfactant used was determined to play an important role in the reaction outcome. The anionic surfactant SDS promoted protein hydrolysis by causing larger protein unfolding (±65% hydrolysis efficiency after 8 days) whereas zwitterionic CHAPS and neutral TX-100 surfactants inhibited hydrolysis by interacting with the MOF's active sites or forming micelles on its surface: around 39% and 31% hydrolysis efficiency after 8 days, respectively.…”

“…Interestingly, while hydrolysis of myoglobin in the presence of CHAPS merely reduced the hydrolysis efficiency, hydrolysis in the presence of TX-100 caused a different cleavage selectivity. 270 Therefore, the addition of specific types of surfactants can influence both the efficiency and selectivity of protein hydrolysis by MOFs. This is extremely valuable for the development of MOFs as catalysts for protein hydrolysis as it shows that the reactivity of MOFs can be tuned through using additives, such as surfactants, and that the MOF catalyst does not completely lose its activity in the presence of surfactants, unlike natural proteases.…”

MOF catalysis meets biochemistry: molecular insights from the hydrolytic activity of MOFs towards biomolecules

“…The surface chemistry of the MOF can also be modified by using surfactants to tune the MOF–substrate interactions, without having to resort to linker modifications. Comparing the hydrolysis of horse heart myoglobin (HHM) by MOF-808 in the absence, 92 and in the presence of different surfactants reveals that different fragmentations are obtained due to the altered MOF–protein interactions (Fig. 2).…”

Molecular Insights into Sequence-Specific Protein Hydrolysis by a Soluble Zirconium-Oxo Cluster Catalyst

“…Inspired by metalloproteases that contain Lewis acid metals in their active sites, various metals were combined with suitable organic ligands to form chelating complexes with a high stability and versatile reactivity that can be used for protein hydrolysis among many other biomolecular transformations. , In the past decade, our group has developed polyoxometalates (POMs) as inorganic ligands for metal cations, where the molecular recognition ability of the POM scaffolds toward protein surfaces was combined with hydrolytically active Lewis acid metal cations (Ce­(IV), Zr­(IV), or Hf­(IV)) to catalyze peptide bond hydrolysis. − Despite this promising proof of concept, the relatively low reactivity of classical transition metal complexes, prompted the development of nanozymes, i.e., nanomaterials with intrinsic enzyme-like properties. − The rapid evolution and growing understanding of nanomaterials allow for the engineering of active centers that mimic those of natural enzymes, resulting in nanomaterials that could address current limitations of natural enzymes. , Despite the remarkable advances in the field, most nanozymes have been designed to exhibit redox activity, mimicking the oxidase/peroxidase family of enzymes. − Nanozymes that mimic other types of enzymes, such as proteases, have seen substantially less development in comparison. − In this regard, metal–organic frameworks (MOFs) have recently emerged as highly reactive and recyclable catalysts for protein hydrolysis. − In particular, MOFs based on Zr­(IV) and Hf­(IV) metal-oxo clusters (MOCs) have been used as catalysts for an array of different biomolecular transformations, including peptide bond hydrolysis, where theoretical studies suggested that MOCs act as the catalytically active sites. ,,, …”