Ferulic acid esterase-III from Aspergillus niger does not exhibit lipase activity

The nine closest matches of the deduced primary sequence of ferulic acid es terase (FAE-III/FAEA) from Aspergillus niger to any other proteins in a red undant database were with fungal lipases (32-26% identity). In this paper w e show that FAE-III does not function significantly as a lipase; it exhibit s no detectable activity on triglycerides, and has 10(5)-fold to 10(6)-fold lower activity than Rhizopus niveus lipase on diglycerides. Conversely, li pases exhibit similar to 2.5 x 10(6)-fold lower ferulic acid esterase activ ity on methyl ferulate compared to FAE-III. Further, lipases possess no det ectable activity on O-[5-O-(trans-feruloyl)-alpha-9-arabinofuranosyl]-(1 -- > 3)-O-beta-3-xylopyranosyl-(1 --> 4)-3-xylopyranose (FAXX), which is the s ubstrate with the highest catalytic efficiency so far reported for FAE-III. These results show that FAE-III exhibits no significant lipase activity, a nd lipases exhibit no significant ferulic acid esterase activity. (C) 1999 Society of Chemical Industry.