In enzymology, a cephalosporin-C transaminase (EC 2.6.1.74) is an enzyme that catalyzes the chemical reaction

(7R)-7-(5-carboxy-5-oxopentanoyl)aminocephalosporinate + D-glutamate ${\displaystyle \rightleftharpoons }$ cephalosporin C + 2-oxoglutarate

Thus, the two substrates of this enzyme are (7R)-7-(5-carboxy-5-oxopentanoyl)aminocephalosporinate and D-glutamate, whereas its two products are cephalosporin C and 2-oxoglutarate.

This enzyme belongs to the family of transferases, specifically the transaminases, which transfer nitrogenous groups. The systematic name of this enzyme class is cephalosporin-C:2-oxoglutarate aminotransferase. Other names in common use include cephalosporin C aminotransferase, and L-alanine:cephalosporin-C aminotransferase. This enzyme participates in penicillin and cephalosporin biosynthesis.

• Aretz W, Sauber K (1988). "Novel D-amino acid transaminase". Ann. N. Y. Acad. Sci. 542: 366–70. PMID 3228235.