Many plastics do not degrade in the environment. Switching production to biodegradable and compostable polymers offers a route to design an inherently limited lifetime into plastics and thereby ensure that the waste plastic does not persist in the environment. Polylactide (PLA) is a widely used biopolymer, but it is efficiently degraded only under industrial composting conditions at high temperatures; the rate of biodegradation under home-composting and soil conditions is low. Now, a PLA-based plastic has been developed in which an engineered enzyme is embedded within the polymer matrix to ensure rapid biodegradation and composting at room temperature.

First, Guicherd et al. isolated and purified a new PLA depolymerase which they called PAM from the thermophilic bacterium Actinomadura keratinilytica T16-1. Characterization showed that PAM was more active for PLA depolymerization than proteinase K (a commonly used enzyme). The structure of PAM was then solved using X-ray crystallography, which enabled modeling of its depolymerase activity. Next, the team introduced mutations into PAM to create a highly efficient depolymerase. The processing of PLA plastics occurs at high temperatures, which can deactivate enzymes, so Guicherd et al. created a hyper-thermostable PLA hydrolase by grafting the beneficial mutations of PAM onto a thermostable scaffold.

许多塑料不会在环境中降解。将生产转向可生物降解和可堆肥聚合物的生产提供了一种设计塑料固有有限寿命的途径，从而确保废塑料不会在环境中持续存在。聚丙交酯（PLA）是一种广泛使用的生物聚合物，但它只有在高温工业堆肥条件下才能有效降解；家庭堆肥和土壤条件下的生物降解率较低。现在，人们已经开发出一种基于 PLA 的塑料，其中将工程酶嵌入聚合物基质中，以确保在室温下快速生物降解和堆肥。

首先，吉谢德等人。从嗜热细菌Actinomadura keratinilytica T16-1 中分离并纯化出一种新的 PLA 解聚酶，将其称为 PAM。表征表明，PAM 对 PLA 解聚的活性比蛋白酶 K（常用的酶）更强。然后使用 X 射线晶体学解析 PAM 的结构，从而对其解聚酶活性进行建模。接下来，该团队将突变引入 PAM，以创建高效的解聚酶。 PLA 塑料的加工过程发生在高温下，这会使酶失活，因此 Guicherd 等人。通过将 PAM 的有益突变移植到热稳定支架上，创建了超热稳定 PLA 水解酶。