Document Detail

The chemistry of escapin: identification and quantification of the components in the complex mixture generated by an L-amino acid oxidase in the defensive secretion of the sea snail Aplysia californica.
MedLine Citation:
PMID:  19130530     Owner:  NLM     Status:  MEDLINE    
Escapin is an L-amino acid oxidase in the ink of a marine snail, the sea hare Aplysia californica, which oxidizes L-lysine (1) to produce a mixture of chemicals which is antipredatory and antimicrobial. The goal of our study was to determine the identity and relative abundance of the constituents of this mixture, using molecules generated enzymatically with escapin and also using products of organic syntheses. We examined this mixture under the natural range of pH values for ink-from approximately 5 at full strength to approximately 8 when fully diluted in sea water. The enzymatic reaction likely forms an equilibrium mixture containing the linear form alpha-keto-epsilon-aminocaproic acid (2), the cyclic imine Delta(1)-piperidine-2-carboxylic acid (3), the cyclic enamine Delta(2)-piperidine-2-carboxylic acid (4), possibly the linear enol 6-amino-2-hydroxy-hex-2-enoic acid (7), the alpha-dihydroxy acid 6-amino-2,2-dihydroxy-hexanoic acid (8), and the cyclic aminol 2-hydroxy-piperidine-2-carboxylic acid (9). Using NMR and mass spectroscopy, we show that 3 is the major component of this enzymatic product at any pH, but at more basic conditions, the equilibrium shifts to produce relatively more 4, and at acidic conditions, the equilibrium shifts to produce relatively more 2, 7, and/or 9. Studies of escapin's enzyme kinetics demonstrate that because of the high concentrations of escapin and L-lysine in the ink secretion, millimolar concentrations of 3, H(2)O(2), and ammonia are produced, and also lower concentrations of 2, 4, 7, and 9 as a result. We also show that reactions of this mixture with H(2)O(2) produce delta-aminovaleric acid (5) and delta-valerolactam (6), with 6 being the dominant component under the naturally acidic conditions of ink. Thus, the product of escapin's action on L-lysine contains an equilibrium mixture that is more complex than previously known for any L-amino acid oxidase.
Michiya Kamio; Ko-Chun Ko; Shilong Zheng; Binghe Wang; Stacy L Collins; Giovanni Gadda; Phang C Tai; Charles D Derby
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Chemistry (Weinheim an der Bergstrasse, Germany)     Volume:  15     ISSN:  1521-3765     ISO Abbreviation:  Chemistry     Publication Date:  2009  
Date Detail:
Created Date:  2009-02-02     Completed Date:  2009-03-04     Revised Date:  2013-01-08    
Medline Journal Info:
Nlm Unique ID:  9513783     Medline TA:  Chemistry     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  1597-603     Citation Subset:  IM    
Department of Biology, Georgia State University, P.O. Box 4010, Atlanta, GA 30302-4010, USA.
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MeSH Terms
Alkenes / chemistry,  metabolism
Amino Acids / chemistry,  metabolism*
Amino Acids, Neutral / chemistry,  metabolism
Anti-Bacterial Agents / chemistry,  metabolism
Aplysia / enzymology*
Hydrogen Peroxide / metabolism
Hydrogen-Ion Concentration
Imines / chemistry,  metabolism
L-Amino Acid Oxidase / chemistry,  metabolism*
Lysine / metabolism
Magnetic Resonance Spectroscopy
Piperidones / chemistry,  metabolism
Spectrometry, Mass, Electrospray Ionization
Grant Support
Reg. No./Substance:
0/Alkenes; 0/Amino Acids; 0/Amino Acids, Neutral; 0/Anti-Bacterial Agents; 0/Imines; 0/Piperidones; 56-87-1/Lysine; 660-88-8/5-aminovaleric acid; 7722-84-1/Hydrogen Peroxide; EC Acid Oxidase; WLN0GQQ6EK/2-piperidone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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