Chemical modifications of proteins and their applications in metalloenzyme studies

Abstract

Protein chemical modifications are important tools for elucidating chemical and biological functions of proteins. Several strategies have been developed to implement these modifications, including enzymatic tailoring reactions, unnatural amino acid incorporation using the expanded genetic codes, and recognition-driven transformations. These technologies have been applied in metalloenzyme studies, specifically in dissecting their mechanisms, improving their enzymatic activities, and creating artificial enzymes with non-natural activities. Herein, we summarize some of the recent efforts in these areas with an emphasis on a few metalloenzyme case studies.

Chemo- and Site-Selective Lysine Modification of Peptides and Proteins under Native Conditions Using the Water-Soluble Zolinium

“…Chemo- and site-selective modification of specific residue(s) of target peptides or proteins can greatly advance both chemical biology research and drug discovery. − Though the covalent modification of the peptides and proteins in nature is generally ruled by enzymes, medicinal chemists have been engaged in developing convenient chemical tools to selectively functionalize the aimed peptides and proteins in the past few decades. Encouragingly, a variety of reagents for selectively modifying target amino acid residue(s) have been developed aiming at serine, tyrosine, histidine, glycine, methionine, cysteine, − carboxyl residues, and N terminus .…”

Chemical and Enzymatic Methods for Post-Translational Protein–Protein Conjugation

“…This selectivity, coupled with the diversity provided by over 200 reported UAAs, has led to the utilization of GCE, with a particular focus on bispecific antibodies. 91 The most common GCE-mediated approach for preparing bispecific antibodies is to combine two UAAcontaining proteins with a bifunctional reagent featuring a flexible linker. Linker lengths and conjugation sites can be readily optimized, and this modular approach is amenable to the combinatorial generation of broad heterodimer libraries.…”

Protein Modifications: From Chemoselective Probes to Novel Biocatalysts

“…Among lysine chemoselective probes, activated esters (mainly N-hydroxysuccinimide-NHS -esters) are the most widely used reagents. Other reagents include isocyanates and isothiocyanates, sulfonyl chlorides, reductive amination of aldehydes, anhydrides, squaric acids and 2amino-2-methoxyethyl [13,28,34,81]. In contrast to cysteine, lysine ubiquity makes it difficult to develop site-selective labeling strategies.…”