1 research outputs found
Enzymatic Hydrolysis of Polyester Thin Films at the Nanoscale: Effects of Polyester Structure and Enzyme Active-Site Accessibility
Biodegradable polyesters have a large
potential to replace persistent
polymers in numerous applications and to thereby reduce the accumulation
of plastics in the environment. Ester hydrolysis by extracellular
carboxylesterases is considered the rate-limiting step in polyester
biodegradation. In this work, we systematically investigated the effects
of polyester and carboxylesterase structure on the hydrolysis of nanometer-thin
polyester films using a quartz-crystal microbalance with dissipation
monitoring. Hydrolyzability increased with increasing polyester-chain
flexibility as evidenced from differences in the hydrolysis rates
and extents of aliphatic polyesters varying in the length of their
dicarboxylic acid unit and of polyÂ(butylene adipate-co-terephthalate)
(PBAT) polyesters varying in their terephthalate-to-adipate ratio
by Rhizopus oryzae lipase and Fusarium solani cutinase. Nanoscale nonuniformities
in the PBAT films affected enzymatic hydrolysis and were likely caused
by domains with elevated terephthalate contents that impaired enzymatic
hydrolysis. Yet, the cutinase completely hydrolyzed all PBAT films,
including films with a terephthalate-to-adipate molar ratio of one,
under environmentally relevant conditions (pH 6, 20 °C). A comparative
analysis of the hydrolysis of two model polyesters by eight different
carboxylesterases revealed increasing hydrolysis with increasing accessibility
of the enzyme active site. Therefore, this work highlights the importance
of both polyester and carboxylesterase structure to enzymatic polyester
hydrolysis