Polyester hydrolytic and synthetic activity catalyzed by the medium-chain-length poly(3-hydroxyalkanoate) depolymerase from Streptomyces venezuelae SO1

• Published in: Applied microbiology and biotechnology 2013, Vol.97 (1), p.211-222
• Main Authors: Santos, Marta, Gangoiti, Joana, Keul, Helmut, Möller, Martin, Serra, Juan L., Llama, María J.
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Biomedical and Life Sciences; Biotechnologically Relevant Enzymes and Proteins; Biotechnology; Butyrolactone; Carboxylic Ester Hydrolases - chemistry; Carboxylic Ester Hydrolases - isolation & purification; Carboxylic Ester Hydrolases - metabolism; Chemical reactions; Detergents; Dithiothreitol; Enzymatic activity; Enzyme Activators - metabolism; Enzyme Inhibitors - metabolism; Enzyme Stability; Enzymes; Ethylenediaminetetraacetic acids; Homogeneity; Hydrogen-Ion Concentration; Hydrolysis; Isoelectric Point; Life Sciences; Low concentrations; Microbial Genetics and Genomics; Microbiology; Molecular Weight; Observations; Organic solvents; Physiological aspects; Poly-3-hydroxybutyrate; Polycaprolactone; Polyesters; Polyesters - metabolism; Polyethylene; Polyethylene succinate; Polyhydroxyalkanoates; Polyhydroxybutyric acid; Polylactic acid; Polymerization; Properties; Ring opening polymerization; Streptomyces; Streptomyces - enzymology; Streptomyces venezuelae; Substrate Specificity; Temperature
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-012-4210-1

The extracellular medium-chain-length polyhydroxyalkanote (MCL-PHA) depolymerase from an isolate identified as Streptomyces venezuelae SO1 was purified to electrophoretic homogeneity and characterized. The molecular mass and p I of the purified enzyme were approximately 27 kDa and 5.9, respectively. The depolymerase showed its maximum activity in the alkaline pH range and 50 °C and retained more than 70 % of its initial activity after 8 h at 40 °C. The MCL-PHA depolymerase hydrolyzes various p -nitrophenyl-alkanoates and polycaprolactone but not polylactide, poly-3-hydroxybutyrate, and polyethylene succinate. The enzymatic activity was markedly enhanced by the presence of low concentrations of detergents and organic solvents, being inhibited by dithiothreitol and EDTA. The potential of using the enzyme to produce ( R )-3-hydroxyoctanoate in aqueous media or to catalyze ester-forming reactions in anhydrous media was investigated. In this sense, the MCL-PHA depolymerase catalyzes the hydrolysis of poly-3-hydroxyoctanoate to monomeric units and the ring-opening polymerization of β-butyrolactone and lactides, while ε-caprolactone and pentadecalactone were hardly polymerized.