聚[(R)-3-羟基丁酸酯]的酶促降解：机制、动力学、后果。

Enzymatic degradation of poly-[(R)-3-hydroxybutyrate]: Mechanism, kinetics, consequences.

机构信息

Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O. Box 91, Hungary; Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1519 Budapest, P.O. Box 286, Hungary.

Department of Applied Biotechnology and Food Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O. Box 91, Hungary; Laboratory of Genome Metabolism and Repair, Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1519 Budapest, P.O. Box 286, Hungary.

出版信息

Int J Biol Macromol. 2018 Jun;112:156-162. doi: 10.1016/j.ijbiomac.2018.01.104. Epub 2018 Feb 26.

DOI:10.1016/j.ijbiomac.2018.01.104

PMID:29414726

Abstract

Poly-[(R)-3-hydroxybutyrate] (PHB) films prepared by compression molding and solvent casting, respectively, were degraded with the intracellular depolymerase enzyme natively synthetized by the strain Bacillus megaterium. Quantitative analysis proved that practically only (R)-3-hydroxybutyric acid (3-HBA) forms in the enzyme catalyzed reaction, the amount of other metabolites or side products is negligible. The purity of the product was verified by several methods (UV-VIS spectroscopy, liquid chromatography, mass spectroscopy). Degradation was followed as a function of time to determine the rate of enzymatic degradation. Based on the Michaelis-Menten equation a completely new kinetic model has been derived which takes into consideration the heterogeneous nature of the enzymatic reaction. Degradation proceeds in two steps, the adsorption of the enzyme onto the surface of the PHB film and the subsequent degradation reaction. The rate of both steps depend on the preparation method of the samples, degradation proceed almost twice as fast in compression molded films than in solvent cast samples. The model can describe and predict the formation of the reaction product as a function of time. The approach can be used even for the commercial production of 3-HBA, the chemical synthesis of which is complicated and expensive.

摘要

聚[(R)-3-羟基丁酸酯]（PHB）薄膜分别通过压缩成型和溶剂浇铸制备，然后用菌株巨大芽孢杆菌天然合成的细胞内解聚酶进行降解。定量分析证明，在酶催化反应中实际上只形成（R）-3-羟基丁酸（3-HBA），其他代谢物或副产物的量可以忽略不计。通过多种方法（UV-VIS 光谱法、液相色谱法、质谱法）验证了产物的纯度。通过跟踪随时间的降解来确定酶降解的速率。基于米氏方程，衍生出了一个全新的动力学模型，该模型考虑了酶反应的非均相性质。降解分两步进行，酶吸附到 PHB 薄膜的表面，然后进行后续的降解反应。这两个步骤的速率都取决于样品的制备方法，压缩成型薄膜中的降解速度几乎是溶剂浇铸样品的两倍。该模型可以描述和预测反应产物随时间的形成。即使对于 3-HBA 的商业化生产，该方法也可以使用，因为其化学合成复杂且昂贵。