:Horrilysin

{{Infobox enzyme

| Name = Horrilysin

| EC_number = 3.4.24.47

| CAS_number = 84056-81-5

| GO_code =

| image =

| width =

| caption =

}}

Horrilysin ({{EC number|3.4.24.47}}, Crotalus horridus metalloendopeptidase, hemorrhagic proteinase IV, Crotalus horridus horridus venom hemorrhagic proteinase) is an enzyme.{{cite journal | vauthors = Civello DJ, Duong HL, Geren CR | title = Isolation and characterization of a hemorrhagic proteinase from timber rattlesnake venom | journal = Biochemistry | volume = 22 | issue = 4 | pages = 749–55 | date = February 1983 | pmid = 6340728 | doi = 10.1021/bi00273a007 }}{{cite journal | vauthors = Civello DJ, Moran JB, Geren CR | title = Substrate specificity of a hemorrhagic proteinase from timber rattlesnake venom | journal = Biochemistry | volume = 22 | issue = 4 | pages = 755–62 | date = February 1983 | pmid = 6340729 | doi = 10.1021/bi00273a008 }} This enzyme catalyses the following chemical reaction

: Cleavage of only the single bond Ala¹⁴-Leu in the insulin B chain, Ser¹²-Leu in the A chain, and Ile-Gly, Pro-Ala, and Ser-Trp in melittin

This endopeptidase is present in the venom of the timber rattlesnake (Crotalus horridus horridus)