Human Cystathionine Beta-synthase, CBS ELI

Hydro-lyase catalyzing the first step of the transsulfuration pathway, where the hydroxyl group of L-serine is displaced by L-homocysteine in a beta-replacement reaction to form L-cystathionine, the precursor of L-cysteine.

This catabolic route allows the elimination of L-methionine and the toxic metabolite L-homocysteine (PubMed: 23981774, PubMed: 20506325, PubMed: 23974653).

Also involved in the production of hydrogen sulfide, a gasotransmitter with signaling and cytoprotective effects on neurons (By similarity).