Detection of esterase activity converting renieramycin M to jorunnamycin a in the crude enzyme extracts of jorunna funebris

Abstract

JornnamycinA, a member of the bis-tetrahydroisoquinolinequinone alkaloids, has been recently used as an important starting material to prepare various 22-O-acyl derivatives of renieramycin M. It was synthesized by chemical reactions to remove the 22-O-angeloyl of renieramycin M. Besides, jorunnamycin A was recently isolated from a marine nudibranch Jorunna funebris. Our preliminary result suggested that the crude enzyme extract prepared from viseral organs of J. funebris possibly contained the esterase enzyme. The enzyme extract was able to convert renieramycin M to jorunnamycin A by exhibiting the catalytic activity for ester bond hydrolysis of the 22-O-angeoyl moiety of renieramycin M. The enzyme was suitably precipitated by ammonium sulfate at the concentrations of 55-75%. According to our study, the optimal condition for the enzyme activity was performed with Tricine buffer at 45C and pH 8. Additionally, the crude enzyme showed specificity to the renieramycin structures as follows: i) C-15 and C-18 must be a quinone moiety, ii) C-14 should not contain an oxygenated substituent, iii) the trans double bond geometry at C-25 is more preferable than the cis, and iv) the 22-O-aliphatic acyl group containing more than 5 carbons is less favorable than the shorter chain. This is the first study to report the information of the esterase enzyme from the nudibranch J. funebris which is highly specific to the substrate renieramycin M. The enzyme will be useful as an alternative approach replacing the chemical reactions to prepare jorunnamycin A.