01835nam a2200229Ia 4500 MX-MdCICY 20260521091209.0 CICY B-10326 Enzymatic Ring-Opening Polymerization of Lactones by Lipase Catalyst: Mechanistic Aspects Macromol. Symp., 240, p.178-185, 2006 Mechanistic aspects of lipase-catalyzed ring-opening polymerization (ROP)of lactones to give polyesters are discussed from accumulated experimental data and new insight. Comparison of the ROP reactivity by lipase catalyst with the anionic ROP reactivity by a metal-catalyst clearly demonstrates the characteristics of lipase catalysis; the larger ring-sized monomers with lower ring strain showed higher polymerizability than medium ring-sized ones, in contrast to the anionic ROP showing the reverse direction where the ring strain of monomer is operative. The enzyme-catalysis involves an acyl-enzyme intermediate formation as a key-step. From the copolymerization results a new mechanism is proposed, that involves the formation of the acyl-enzyme intermediate (acylation step)and/or the nucleophilic attack of the propagationg alcohol end to the carbonyl carbon of the intermediate to open the monomer ring (deacylation step)as the rate-determining step. The structure of the propagating alcohol end (primary or secondary)affects much on which step is more operative. CATALYSIS LACTONE LIPASE ENZYME REACTION MECHANISM RING-OPENING POLYMERIZATION Kobayashi, S. https://drive.google.com/file/d/1zzPia3QVtFd9XjF-PaYycrpG9S8NVfgI/view?usp=drivesdk Para ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx Loc REF1 250602s9999 xx |||||s2 |||| ||und|d 20503 20503 0 0 Loc 0 0 F1 CICY CICY RE 2025-06-25 0 B-10326 2025-06-25 14:06:29 2025-06-25 REF1