CAL-B catalyzed regioselective bulk polymerization ofl-aspartic acid diethyl ester to α-linked polypeptides

Abstract

This paper reports that the bulk polymerization of l-aspartic acid diethyl ester catalyzed by immobilized CAL-B at 80 °C for 24 h gives primarily (∼95%) α-linked poly(l-aspartate) in 70% yield with DP = 50 and regioselectivity (α/β) = 94 : 6. Plots of log{[M]/[M]} vs. time and DPvs. conversion indicate that this polymerization proceeds in a controlled manner by a chain-growth mechanism up to 90% conversion. Thereafter, competition occurs between chain growth and step mechanisms.

Protease-Catalyzed l-Aspartate Oligomerization: Substrate Selectivity and Computational Modeling

“…Poly­(β-Et-α- l -Asp) adopts a right-handed α-helix conformation in chloroform and undergoes a helix–coil transition upon addition of TFA. − Figure A shows that the α-H (D) shifts downfield as TFA (0.3–10%) was added to the oligoaspartate/CDCl 3 solution. This downfield shift is consistent with that observed for the helix–coil transition of poly­(α- l -amino acids). − The α-H in poly­(α-Et-β- l -Asp) undergoes an upfield shift thus following the opposite trend under the same experimental conditions. The formation of α-linked polyaspartate ethyl ester was further confirmed by a CD spectrum conducted in pure chloroform (Figure b).…”

Enantio‐, Regio‐, and Chemoselective Lipase‐Catalyzed Polymer Synthesis

“…Finally, lipase showed high regioselectivity in the enzymatic polymerization of l ‐aspartic acid diethyl ester, yielding mainly α‐linked poly( l ‐aspartate) (≈95%) . The structure of α‐linked and β‐linked poly( l ‐aspartate) was shown in Figure 8 .…”

“…[78] Finally, lipase showed high regioselectivity in the enzymatic polymerization of l-aspartic acid diethyl ester, yielding mainly α-linked poly(l-aspartate) (≈95%). [81] The structure of α-linked and β-linked poly(l-aspartate) was shown in Figure 8. The polymerization proceeded in a controlled manner, with a product yield of 70% and the degree of polymerization of ≈50.…”

Facile terminal functionalization of peptides by protease-catalyzed chemoenzymatic polymerization toward synthesis of polymeric architectures consisting of peptides

“…16 So far, the molecular weight obtained by the chemoenzymatic polymerization in aqueous media has reached up to approximately 2000 Da depending on the amino acid residues that characterize the reactivity of monomers and the solubility of resulting polypeptides in water. 29 The use of water-free conditions such as solution polymerization in an organic solvent 35 or bulk polymerization 36 can improve the molecular weight of the obtained polypeptides, although the greenness of the chemoenzymatic synthesis is deteriorated. The papain-catalyzed polymerization in the presence of 1 was also applied to other amino acid esters.…”