Synthesis, characterization of lipid-conjugated aminoacids and esterase activity

Rout, Nilesh Kumar (2018) Synthesis, characterization of lipid-conjugated aminoacids and esterase activity. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Nilesh Kumar Rout (13MS088)) 13MS088.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

we hypothesize that properly lipid-conjugated amino acids may form micellar or vesicular surface and the functional groups at surface are in close proximity and may establish additional interactions to contribute the catalytic activity of the nanostructure. In addition, bringing two vesicles at close proximity may establish the 3-dimensional structure. To test the hypothesis, in the present report, we synthesized lipidated serine, histidine and aspartic acid having various long chains from C4 (butyl) to C14 (myristoyl). We have determined the critical micellar concentration of lipidated amino acids using pyrene as a fluorophore. Results on the esterase activity suggest that histidine containing surfaces able to hydrolyzing the ester bond whereas the surfaces having serine and aspartate moiety are poorly reactive. We further tested the hydrolyzing ability of mixed surface (surface with two amino acids) and found that surface having the mixture of lipid-conjugated histidine and serine possess most reactivity towards hydrolysis. From all the results we can conclude that only histidine containing surfaces catalyze the esterase like activity. Lauryl-histidine hydrolyzes the ester more efficiently than octyl, butyl-histidine and only histidine. Hence acyl chain length has some activity. Lauryl-histidine and lauryl-serine together exhibit better ester hydrolyzing ability than any other amphiphile combination. Lauryl-aspartate appears not to play any role in catalyzing the reaction, instead it is inhibiting the reaction.

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