Cystathionine beta synthase

Cystathionine-β-synthase, also known as CBS, is an <a href="/facts/Enzyme/DSI1Fh7y">enzyme</a> (<a href="/facts/Enzyme_Commission_number/Y5GNLRKX">EC</a> <a href="https://www.enzyme-database.org/query.php?ec=4.2.1.22">4.2.1.22</a>) that in humans is encoded by the CBS <a href="/facts/Gene/e1swwPY6">gene</a>. It catalyzes the first step of the <a href="/facts/Transsulfuration_pathway/aK1yhJwL">transsulfuration pathway</a>, from <a href="/facts/Homocysteine/m4cgrRBG">homocysteine</a> to <a href="/facts/Cystathionine/n4ytaqjj">cystathionine</a>:

<a href="/facts/Serine/4duVl30B">L-serine</a> + <a href="/facts/Homocysteine/m4cgrRBG">L-homocysteine</a> 
 
 
 
 ⇌
 
 
 {\displaystyle \rightleftharpoons }
 
 <a href="/facts/Cystathionine/n4ytaqjj">L-cystathionine</a> + <a href="/facts/Water_(molecule)/FFsl65l1">H2O</a>
CBS uses the <a href="/facts/Cofactor_(biochemistry)/AGo0PCUU">cofactor</a> <a href="/facts/Pyridoxal-phosphate/GTGIzISg">pyridoxal-phosphate</a> (PLP) and can be <a href="/facts/Allosterically/alMRuyt9">allosterically</a> regulated by effectors such as the ubiquitous cofactor <a href="/facts/S-adenosyl-L-methionine/oAsJ0SSR">S-adenosyl-L-methionine</a> (adoMet). This enzyme belongs to the family of <a href="/facts/Lyase/Ll2jFfhU">lyases</a>, to be specific, the hydro-lyases, which cleave carbon-oxygen bonds.
CBS is a multidomain enzyme composed of an N-terminal enzymatic domain and two <a href="/facts/CBS_domain/vdN5HtrI">CBS domains</a>. The CBS gene is the most common locus for mutations associated with <a href="/facts/Homocystinuria/CGKNanae">homocystinuria</a>.

Cystathionine beta synthase open-in-new

Cystathionine beta synthase