In enzymology, a diguanidinobutanase (EC 3.5.3.20) is an enzyme that catalyzes the chemical reaction

1,4-diguanidinobutane + H₂O ${\displaystyle \rightleftharpoons }$ agmatine + urea

Thus, the two substrates of this enzyme are 1,4-diguanidinobutane and H₂O, whereas its two products are agmatine and urea.

This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amidines. The systematic name of this enzyme class is 1,4-diguanidinobutane amidinohydrolase.

• Yorifuji T, Kaneoke M, Shimizu E, Shiota K, Matsuo R (1989). "Degradation of alpha,omega-diguanidinoalkanes and a novel enzyme, diguanidinobutane amidohydrolase, in Pseudomonas putida". Agric. Biol. Chem. 53: 3003–3009. doi:10.1271/bbb1961.53.3003.