Bacterial enzymes catalyzing conversion of amino acids to volatile sulfur compounds

Bacterial enzymes catalyzing the conversion of amino acids to volatile sulfur compounds (VSCs) are a group of lyases, primarily L-methionine gamma-lyase (MGL) and cystathionine lyases, found in anaerobic bacteria such as Porphyromonas gingivalis and Fusobacterium nucleatum (Yoshimura et al., 2000). These enzymes degrade sulfur-containing amino acids like methionine and cysteine into malodorous gases, including hydrogen sulfide (H2S) and methyl mercaptan (CH3SH), which are the primary drivers of oral malodor or halitosis (Persson et al., 1990). Beyond oral health, these enzymes in the gut microbiome contribute to the production of H2S, which at high concentrations is associated with mucosal inflammation and the pathogenesis of inflammatory bowel disease and colorectal cancer (Carbonero et al., 2012). Therapeutic targeting of these enzymes involves the use of metal ions, particularly zinc, which can directly inhibit enzyme activity by binding to active site thiols or by sequestering the produced VSCs as non-volatile sulfides (Young et al., 2003). Additionally, antimicrobial agents like chlorhexidine and cetylpyridinium chloride are used to reduce the load of VSC-producing bacteria in the oral cavity (Roldán et al., 2003). Monitoring VSC levels in breath serves as a key biomarker for the efficacy of these treatments in clinical settings.

Other names

L-methionine gamma-lyaseMethioninaseCystathionine gamma-lyaseCystathionine beta-lyaseC-S lyasesTryptophanaseVSC-producing enzymes

Inhibition of enzyme catalytic activity through metal ion binding to active site thiols or competitive inhibition, and reduction of VSC-producing bacterial populations via antimicrobial action.