Pycnoporopepsin (, proteinase Ia, Pycnoporus coccineus aspartic proteinase, Trametes acid proteinase) is an enzyme. This enzyme catalyses the following chemical reaction
Similar to pepsin A, but narrower, cleaving only three bonds in the B chain of insulin: Ala<sup>14</sup>-Leu, Tyr<sup>16</sup>-Leu, and Phe<sup>24</sup>-Phe