Polyester hydrolytic and synthetic activity catalyzed by the medium-chain-length poly(3-hydroxyalkanoate) depolymerase from Streptomyces venezuelae SO1.
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 pI 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.
Enzyme and Cell Technology Group, Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain.
Marta
M
Santos
Joana
J
Gangoiti
Helmut
H
Keul
Martin
M
Möller
Juan L
JL
Serra
María J
MJ
Llama
D002265:Carboxylic Ester Hydrolases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D020536:Enzyme Activators / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007526:Isoelectric Point; D008970:Molecular Weight; D011091:Polyesters / Q000378:metabolism*; D013302:Streptomyces / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D011091:Polyesters; D002265:Carboxylic Ester Hydrolases; C077226:poly(3-hydroxyalkanoic acid) depolymerase