L-lysine derivative tripeptide

Zhou et al. described the synthesis of pH-sensitive biodegradable PUs. They used a novel pH-sensitive macrodiol containing acid-cleavable hydrazone linkers, poly(E-caprolactone)-hydrazone-poly(ethylene glycol)-hydiazone- ly(E-caprolactone) diol (PCL-Hyd-PEG-Hyd-PCL). The macrodiol was used with L-lysine ethyl ester diisocyanate (LDI) and L-lysine-derived tripeptide as chain extender [47]. These PUs could self-assemble into micelles in aqneons solutions. Later, the same research group synthesized pH-sensitive polymers nsing 1,4-bntanediol as chain extenders and suggested its use as antitumor drug carriers [41]. 

A simple example is the tripeptide precursor of the penicillin antibiotics, called ACV, an abbreviation for S-(L-a-aminoadipyl)-L-cysteinyl-D-valine. The amino acid precursors for ACV are L-a-aminoadipic acid (an unusual amino acid derived by modification of L-lysine), L-cysteine, and L-valine (not o-valine). 

A series of derivatives of the ester 37, having amino acid or peptide residues linked through the carboxyl group of the lactic acid residue, has been described. Their exact structures depend on the growth conditions and the bacterial strain used. The chain attached may contain L-alanine 7,151,154,155 the dipeptide L-alanyl-D-glutamic acid 156,157 the tripeptides L-alanyl-y-D-glutamyl-L-lysine,157-160 L-al-... 

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