REACTION OF A LYSYL RESIDUE ANALOG WITH E-2-OCTENAL

The reaction of E-2-octenal and N-2-(carbobenzyloxy)-L-lysine was investigated and the products analyzed to identify the components that produce a significant loss of lysine residues in the reaction of E-2-octenal and proteins. When the mixture of N-2-(carbobenzyloxy)-L-lysine and E-2-octenal was incubated at pH 7.0 and 37 degrees C for 24 h, seven products were isolated, and their structures are suggested to be E-2-octenoic acid (4), 4-butyl-E-2-E-4-E-6-dodecatrien-1-al (3), 6-ethyl-5-pentyl-1,3-cyclohexadiene (1), 3,8-dibutyl-1-(2'-butyl-4'-formyl-1'-E-3'-E-butadien-1'-yl)-5-pentyl-2,6-dihydronaftalene (2), 1-(N-2-(carbobenzyloxy)-L-lysyl)-2-(1'-carboxymethyl)-4-pentylpyridinium betaine (6), 1-(N-2-(carbobenzyloxy)-L-lysyl)-2-(3'-carboxy-2'-E-propen-1'-yl)-4-pentylpyridinium betaine (7) and bis(1-(N-2-(carbobenzyloxy)-L-lysyl)-2-(3'-carboxy-2'-propen-1',2'-diyl)-4-pentylpyridinium betaine) (5). Plausible mechanisms for the formation of those compounds are proposed.