Sustainable Enzymatic Preparation of Polyaspartate Using a Bacterial Protease

Abstract

Diethyl l-aspartate was polymerized by a bacterial protease from Bacillus subtilis (BS) in organic solvent at a temperature between 30 and 50 degrees C to yield alpha-linked poly(ethyl l-aspartate) having an M(w) of up to 3700 and a maximum polymer yield of 85%. The best polymerization conditions were the 40 degrees C polymerization of diethyl l-aspartate using 30% protease BS containing 4.5 vol % water in acetonitrile for 2 days. Poly(ethyl l-aspartate) was readily depolymerized by the enzyme into the oligomeric and monomeric l-aspartate in aqueous acetonitrile. Poly(sodium aspartate) prepared by the saponification of poly(ethyl l-aspartate) was readily biodegradable by activated sludge obtained from the municipal sewage treatment plant. Also, poly(sodium aspartate) was depolymerized by the hydrolase enzyme into the monomeric aspartate. These results may indicate the sustainable chemical recycling and biorecycling of this polymer.

Papain Catalyzed (co)Oligomerization of α-Amino Acids

“…TRIS buffer is used for some protease mediated reactions [28][29][30][31] including papain [31,33], so it is not likely that the enzyme loses its activity in this buffer. However, in the oligomerization of amino acids [16][17][18][19][20][21][22], TRIS was not reported; only citrate and phosphate buffers are mentioned. and oligomer fragments.…”

“…Others used bovine lung proteinase [14], ficin and Cathepsin-C [15] a protease from Streptomyces sp. was used for the oligomerization of diethyl L-aspartate by Matsumura et al [16] and Soeda et al [17].…”

Cysteine Proteases

“…Papain is used in the synthesis of amino acids (Rai and Taneja, 1998), biologically active peptides (Gill et al, 1996), anticancer drugs (Du, 2003) and polyaspartate (Soeda et al, 2003).…”

Biodegradable Polymers: Recent Developments and New Perspectives

“…As commonly used proteases cleave and form α-amide linkages, the resultant poly(amino acid)s synthesized by the proteases are composed of α-units [145][146][147][148][149][150][151]. Due to the novel substrate specificity of PahZ1 enzymes, their application to enzyme-catalysed polymerization may result in the synthesis of β-linked PAA (β-PAA) possessing the unexpected properties mentioned above.…”