Involved in the synthesis of hordatines (antifungal hydroxycinnamoylagmatine derivatives). Specific for agmatine as the acyl acceptor, inactive towards tyramine and putrescine. Has activity with the acyl donors 4-coumaroyl-CoA, cinnamoyl-CoA, caffeoyl-CoA, feruloyl-CoA, and to a lesser extent sinapoyl-CoA. 4-coumaroyl-CoA + agmatine = CoA + H(+) + N-(4-guanidinobutyl)-4-hydroxycinnamamide Inhibited by DEPC. Completely inhibited by ZnSO(4), strongly inhibited by CuSO(4), partially inhibited by MnCl(2). Unaffected by MgCl(2) or CaCl(2). Optimum pH is 7.5. Half maximum activity is seen at pH 6.9 and 8.1. Optimum temperature is 40 degrees Celsius. Monomer. Belongs to the plant acyltransferase family.