CTH
CTH (cystathionine gamma-lyase, also known as CSE) is a cytoplasmic, pyridoxal-5'-phosphate-dependent enzyme that catalyses the final step of the trans-sulfuration pathway, converting L-cystathionine into L-cysteine. It also generates the gasotransmitter hydrogen sulfide (H2S). Browse Assay Genie's current range of CTH research reagents below, or read on for the biology behind the target.
CTH catalyses the last step in the trans-sulfuration pathway from L-methionine to L-cysteine. In a pyridoxal-5'-phosphate (PLP)-dependent reaction, it cleaves L,L-cystathionine into L-cysteine, ammonia and 2-oxobutanoate. Part of the cysteine produced this way is used to make glutathione, the ubiquitous antioxidant, and glutathione synthesis in the liver depends on cysteine availability. The enzyme can also accept homoserine as a substrate and catalyses the elimination of selenocystathionine, which can be derived from the diet, to give selenocysteine, ammonia and 2-oxobutanoate.
Beyond cystathionine, CTH uses L-cysteine and L-homocysteine as substrates, at much lower rates, to produce hydrogen sulfide (H2S). In vitro, it converts two L-cysteine molecules into lanthionine and H2S, and two L-homocysteine molecules into homolanthionine and H2S. This may be particularly relevant in severe hyperhomocysteinemia, a risk factor for cardiovascular disease, diabetes and Alzheimer's disease. CTH also acts as a cysteine-protein sulfhydrase, converting -SH groups to -SSH on specific cysteine residues of targets such as GAPDH, PTPN1 and the NF-kappa-B subunit RELA, thereby regulating their function. Through H2S, it takes part in vasodilation, bone protection and inflammation, and it is essential for myogenesis by contributing to H2S biogenesis in skeletal muscle.
The CTH gene belongs to the trans-sulfuration enzymes family. Its previous name was cystathionase (cystathionine gamma-lyase), and CSE is a commonly used alias. Mutations in the gene cause cystathioninuria, and alternative splicing yields three transcript variants encoding different isoforms. Mouse and rat both have an ortholog named Cth.
CTH completes the conversion of methionine-derived cystathionine into cysteine, making it a central enzyme for studying trans-sulfuration flux.
CTH generates the gaseous signalling molecule H2S from cysteine and homocysteine, linking it to vasodilation, inflammation and bone protection.
CTH sulfhydrates cysteine residues on targets such as GAPDH, PTPN1 and RELA, offering a route to study post-translational regulation by H2S.
Cysteine supplied by CTH contributes to glutathione biosynthesis, relevant to antioxidant defence and liver glutathione synthesis.
CTH is a PLP-dependent enzyme that catalyses the last step of the trans-sulfuration pathway, cleaving L,L-cystathionine into L-cysteine, ammonia and 2-oxobutanoate. It also produces hydrogen sulfide from cysteine and homocysteine, and sulfhydrates target proteins such as GAPDH, PTPN1 and RELA.
CTH is the HGNC symbol for cystathionine gamma-lyase, often abbreviated CSE. Its earlier name was cystathionase (cystathionine gamma-lyase). Alternative splicing of the gene gives three transcript variants that encode different isoforms, so literature may describe the protein under several names.
Mutations in the CTH gene cause cystathioninuria. The enzyme's H2S-producing activity is considered relevant in severe hyperhomocysteinemia, a risk factor for cardiovascular disease, diabetes and Alzheimer's disease. Mouse and rat orthologs are both named Cth; check the datasheet of any product for its validated reactivity.
Related targets and pathway partners for studying trans-sulfuration and H2S biology.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P32929; product specifications from Assay Genie datasheets.