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Sulfur-containing biomolecules such as [Fe-S] clusters, thiamin, biotin, molybdenum cofactor, and sulfur-containing tRNA nucleosides are essential for various biochemical reactions. The amino acid l-cysteine serves as the major sulfur source for the biosynthetic pathways of these sulfur-containing cofactors in prokaryotic and eukaryotic systems. The first reaction in the sulfur mobilization involves a class of pyridoxal-5′-phosphate (PLP) dependent enzymes catalyzing a Cys:sulfur acceptor sulfurtransferase reaction. The first half of the catalytic reaction involves a PLP-dependent single bondS bond cleavage, resulting in a persulfide enzyme intermediate. The second half of the reaction involves the subsequent transfer of the thiol group to a specific acceptor molecule, which is responsible for the physiological role of the enzyme. Structural and biochemical analysis of these Cys sulfurtransferase enzymes shows that specific protein-protein interactions with sulfur acceptors modulate their catalytic reactivity and restrict their biochemical functions.
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This content will become publicly available on March 28, 2026
Protein-derived cofactors: chemical innovations expanding enzyme catalysis
Protein-derived cofactors, formed through posttranslational modification of a single amino acid or covalent crosslinking of amino acid side chains, represent a rapidly expanding class of catalytic moieties that redefine enzyme functionality. Once considered rare, these cofactors are recognized across all domains of life, with their repertoire growing from 17 to 38 types in two decades in our survey. Their biosynthesis proceeds via diverse pathways, including oxidation, metal-assisted rearrangements, and enzymatic modifications, yielding intricate motifs that underpin distinctive catalytic strategies. These cofactors span paramagnetic and non-radical states, including both mono-radical and crosslinked radical forms, sometimes accompanied by additional modifications. While their discovery has accelerated, mechanistic understanding lags, as conventional mutagenesis disrupts cofactor assembly. Emerging approaches, such as site-specific incorporation of non-canonical amino acids, now enable precise interrogation of cofactor biogenesis and function, offering a viable and increasingly rigorous means to gain mechanistic insights. Beyond redox chemistry and electron transfer, these cofactors confer enzymes with expanded functionalities. Recent studies have unveiled new paradigms, such as long-range remote catalysis and redox-regulated crosslinks as molecular switches. Advances in structural biology, mass spectrometry, and biophysical spectroscopy continue to elucidate their mechanisms. Moreover, synthetic biology and biomimetic chemistry are increasingly leveraging these natural designs to engineer enzyme-inspired catalysts. This review integrates recent advances in cofactor biogenesis, reactivity, metabolic regulation, and synthetic applications, highlighting the expanding chemical landscape and growing diversity of protein-derived cofactors and their far-reaching implications for enzymology, biocatalysis, and biotechnology.
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- Award ID(s):
- 2204225
- PAR ID:
- 10623873
- Editor(s):
- Goss, Rebecca
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Chemical Society Reviews
- Volume:
- 54
- Issue:
- 9
- ISSN:
- 0306-0012
- Page Range / eLocation ID:
- 4502 to 4530
- Subject(s) / Keyword(s):
- Protein cofactor amino acid crosslink cysteine-tyrosine crosslink Cys-Tyr noncanonical amino acids unnatural amino acids metalloenzyme autocatalysis
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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