During metabolism carboxylic acids are often activated by conjugation to the thiol of coenzyme A (CoA). The resulting acyl-CoAs comprise a group of ~100 thioester-containing metabolites that can modify protein behavior through non-enzymatic acylation of surface lysine and cysteine residues. We have previously shown that cysteine residues can enhance acetylation of nearby lysine residues in liver and the sites where this occurs are less conserved within the genomes of vertebrates and this correlates with lifespan. This implied a detrimental effect for non-enzymatic ‘acylation’, but the loss of these sites could arise from other acyl-CoA species or even other metabolites that can react with both cysteine and lysine residues. Furthermore, it could occur in any tissue. Unfortunately, the in vivo concentrations of most acyl-CoAs and other metabolites of interest are poorly characterized, particularly outside liver. Thus, we have developed Cysteine-triphenylphosphonium (CysTPP), a mass spectrometry probe that utilizes the S→N acyl-transfer mechanism of ‘native chemical ligation’ to sensitively detect the major acyl-CoAs present in vivo. CysTPP was designed to mimic the reactive protein sites by irreversibly trapping acyl groups on its amine via a thioester intermediate. The triphenylphosphonium cation then facilitates LC-MS/MS detection. Using CysTPP we show that longer-chain (C13-C22) acyl-CoAs often constitute ~60% of the acyl-CoA pool in rat tissues. These hydrophobic longer-chain fatty acyl-CoAs have the potential to non-enzymatically modify protein residues and may be of relevance for protein aggregation-based pathologies.

Sensitive LC-MS/MS quantification of tissue acyl-CoA pools: Potential implications for non-enzymatic protein N-acylation

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.