The enzyme (S)-norcoclaurine synthase () catalyzes the chemical reaction:
This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is 4-hydroxyphenylacetaldehyde hydro-lyase [adding dopamine (S)-norcoclaurine-forming]. Other names in common use include (S)-norlaudanosoline synthase, and 4-hydroxyphenylacetaldehyde hydro-lyase (adding dopamine). This enzyme participates in isoquinoline alkaloid biosynthesis.