In enzymology, an isopenicillin N N-acyltransferase (EC 2.3.1.164) is an enzyme that catalyzes the chemical reaction

phenylacetyl-CoA + isopenicillin N + H₂O ${\displaystyle \rightleftharpoons }$ CoA + penicillin G + L-2-aminohexanedioate

The 3 substrates of this enzyme are phenylacetyl-CoA, isopenicillin N, and H₂O, whereas its 3 products are CoA, penicillin G, and L-2-aminohexanedioate.

This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:isopenicillin N N-acyltransferase. Other names in common use include acyl-coenzyme A:isopenicillin N acyltransferase, and isopenicillin N:acyl-CoA: acyltransferase. This enzyme participates in hydrophobic penicillins biosynthesis.

• Tobin MB, Fleming MD, Skatrud PL, Miller JR (1990). "Molecular characterization of the acyl-coenzyme A:isopenicillin N acyltransferase gene (penDE) from Penicillium chrysogenum and Aspergillus nidulans and activity of recombinant enzyme in Escherichia coli". J. Bacteriol. 172 (10): 5908–14. PMC 526911. PMID 2120195.
• Aplin RT, Baldwin JE, Roach PL, Robinson CV, Schofield CJ. "Investigations into the post-translational modification and mechanism of isopenicillin N:acyl-CoA acyltransferase using electrospray mass spectrometry". Biochem. J. 294: 357–63. PMC 1134462. PMID 8396910.

• Aplin, Robin T.; Baldwin, Jack E.; Cole, Stephen C.J.; Sutherland, John D.; Tobin, Matthew B. (1993). "On the production of α,β-heterodimeric acyl-coenzyme A: isopenicillin N-acyltransferase of Penicillium chrysogenum". FEBS Letters. 319 (1–2): 166–170. doi:10.1016/0014-5793(93)80060-8. ISSN 0014-5793.
• Fernández FJ, Gutierrez S, Velasco J, Montenegro E, Marcos AT, Martín JF (August 1994). "Molecular characterization of three loss-of-function mutations in the isopenicillin N-acyltransferase gene (penDE) of Penicillium chrysogenum". Journal of Bacteriology. 176 (16): 4941–8. PMC 196331. PMID 7519594.
• ALVAREZ, Emilio; MEESSCHAERT, Boudewijn; MONTENEGRO, Eduardo; GUTIERREZ, Santiago; DIEZ, Bruno; BARREDO, Jose L.; MARTIN, Juan F. (1993). "The isopenicillin-N acyltransferase of Penicillium chrysogenum has isopenicillin-N amidohydrolase, 6-aminopenicillanic acid acyltransferase and penicillin amidase activities, all of which are encoded by the single penDE gene". European Journal of Biochemistry. 215 (2): 323–332. doi:10.1111/j.1432-1033.1993.tb18038.x. ISSN 0014-2956.