Abstract
The nine closest matches of the deduced primary sequence of ferulic acid esterase (FAE-III/FAEA) from Aspergillus niger to any other proteins in a redundant database were with fungal lipases (32–26% identity). In this paper we show that FAE-III does not function significantly as a lipase; it exhibits no detectable activity on triglycerides, and has 105-fold to 106-fold lower activity than Rhizopus niveus lipase on diglycerides. Conversely, lipases exhibit ∽2.5×106-fold lower ferulic acid esterase activity on methyl ferulate compared to FAE-III. Further, lipases possess no detectable activity on O–[5–O-(trans-feruloyl)--L-arabinofuranosyl]-(1→3)–O–β-D-xylopyranosyl-(1→4)-D-xylopyranose (FAXX), which is the substrate with the highest catalytic efficiency so far reported for FAE-III. These results show that FAE-III exhibits no significant lipase activity, and lipases exhibit no significant ferulic acid esterase activity.© 1999 Society of Chemical Industry