Immobilized Metal Affinity Chromatography as a Drug Discovery Platform for Metalloenzyme Inhibitors

Identification and characterization of tubulin as Ga(III)-binding protein in T24 cells

Gallium-based metallic drugs and agents have been widely applied for the diagnosis and treatment of diseases such as non-Hodgkin's lymphoma (NHL), but there are few reports on the potential Ga(III)-binding proteins and the related cytotoxic mechanisms for Ga(III). Herein, by using human urinary bladder cancer T24 cells as a model, we identify and report that tubulin is a Ga(III)-binding protein target in T24 cells. Our analyses, including the employment of a series of methods based on immobilized metal affinity chromatography (IMAC), cellular thermal shift assay (CETSA), and immunofluorescence experiments, collectively explained this finding. Our results suggest that the binding of Ga(III) to tubulin led to significant changes in the morphology and distribution of microtubules in cells. The blocked microtubule formation or microtubule depolymerization as a result of the binding of Ga(III) to tubulin may be an important molecular mechanism by which Ga(III) exerts its cytotoxic effects in T24 cells to inhibit tumor cell growth.

Immobilized metal ion affinity chromatography: waltz of metal ions and biomacromolecules

INTRODUCTION

Immobilized metal ion affinity chromatography (IMAC) is an effective method developed in the 1980s for the separation and purification of proteins. The system consists of a solid-phase matrix, a linking ligand, and a metal ion. The method is based on the ability of metal ions to bind specifically to certain specific amino acid residues of proteins, thereby selectively enriching and purifying proteins.

AREAS COVERED

This review aims to describe current knowledge of fundamental principle of IMAC and summarize the supports, chelating ligands, and metal ions of IMAC. In addition, how IMAC technology is used in proteomics and nucleic acids research are highlighted.

EXPERT OPINION

Over the past decades, IMAC has been extensively utilized as a predominant technique for protein enrichment in a variety of biological and medical research, such as disease diagnosis, tumor biomarker identification, protein purification, and nucleic acids research. In the future, IMAC should be integrated with other emerging proteomics technologies to promote the applications of metalloproteomes in disease diagnosis, metallodrug development, and clinical translation.

Second coordination sphere regulates nanozyme inhibition to assist early drug discovery

Early drug discovery is a time- and cost-consuming task requiring enzymes. Although nanozymes with metal sites akin to metallocofactors display similar activities, the lack of proximal amino acids hinders them from more adequately mimicking enzymes for drug discovery purposes. Hence, the rational design of the nanozyme second coordination sphere is desirable yet remains challenging. Herein, we report a nanozyme featuring atomically dispersed Cu-N4 sites with proximal hydroxyl groups (CuNC-OH). Experimental and theoretical results reveal that Cu-N4 site and hydroxyl respectively behave as cofactor and amino acid of the enzymatic pocket to interact with adsorbates, regulating nanozyme activity and inhibition. This mechanism involving dual sites is similar to that of thyroid peroxidases, which enables specific inhibition of CuNC-OH by antithyroid drugs. Based on these findings, a nanozyme-assisted drug discovery kit is established to analyze inhibition features of thyroid peroxidase inhibitors and screen out promising antithyroid drugs with a significant cost reduction compared with traditional enzyme kits.

Metal-based strategies for the fight against COVID-19

The emerging COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has claimed over six million lives globally to date. Despite the availability of vaccines, the pandemic still cannot be fully controlled owing to rapid mutation of the virus that renders enhanced transmissibility and antibody evasion. This is thus an unmet need to develop safe and effective therapeutic options for COVID-19, in particular, remedies that can be used at home. Considering the great success of multi-targeted cocktail therapy for the treatment of viral infections, metal-based drugs might represent a unique and new source of antivirals that resemble a cocktail therapy in terms of their mode of actions. In this review, we first summarize the role that metal ions played in SARS-CoV-2 viral replication and pathogenesis, then highlight the chemistry of metal-based strategies in the fight against SARS-CoV-2 infection, including both metal displacement and chelation based approaches. Finally, we outline a perspective and direction on how to design and develop metal-based antivirals for the fight against the current or future coronavirus pandemic.