4.4.1.28	L-cysteine desulfidase	hydrogen sulfide biosynthesis II (mammalian)	-	
4.2.1.22	cystathionine beta-synthase	hydrogen sulfide biosynthesis II (mammalian)	-	
4.4.1.1	cystathionine gamma-lyase	hydrogen sulfide biosynthesis II (mammalian)	-	
4.4.1.2	homocysteine desulfhydrase	hydrogen sulfide biosynthesis II (mammalian)	-