Chemo-Enzymatic Synthesis of Poly(lactate-co-(3-hydroxybutyrate)) by a Lactate-Polymerizing Enzyme

Abstract

In our previous paper, we synthesized poly-3-hydroxybutyrate [P(3HB)] by using the waterorganic-solvent two-phase reaction system (TPRS), in which (R)-3-hydroxybutyrylCoA [(R)-3HBCoA] was continuously supplied to PHA synthase by the ester exchange reaction between CoA and thiophenol in thiophenyl (R)-3HB [(R)-3HBTP]. By applying TPRS to the screening, we found a lactate-(LA-) polymerizing enzyme from PHA synthases. The enzyme was an engineered PHA synthase, which stereoselectively copolymerized (R)-LA together with (R)-3HB. NMR and GPC revealed that the TPRS successfully synthesized poly(lactate-co-(3-hydroxybutyrate)) [P(LA-co-3HB)] using the LA-polymerizing enzyme as a catalyst. The molar ratios of LA in the copolymers were controllable in the range of 0 to 36 mol% by varying the ratio of (R)-LATP and (R)-3HBTP fed into the TPRS. The number-average molecular weight and the polydispersity of P(36 mol%-co-3HB) were 1.1 × 10 4 and 1.4, respectively. This is the first report on the chemo-enzymatic synthesis of P(LA-co-3HB) by a LA-polymerizing enzyme.

Biosynthesis of glycolate-based polyesters containing medium-chain-length 3-hydroxyalkanoates in recombinant Escherichia coli expressing engineered polyhydroxyalkanoate synthase

“…PhaC1STQK was originally created through the engineering of PHA synthase in order to enhance the activity toward 3HB-CoA (Taguchi and Doi, 2004;Takase et al, 2003). The activity of PhaC1STQK toward LA-CoA was found by means of an in vitro chemo-enzymatic synthesizing system and formally designated LPE (Taguchi et al, 2008;Tajima et al, 2009). The result of the present study demonstrated that PhaC1STQK also recognized glycolyl-CoA as a monomer substrate.…”

Biodegradable Polymers: Recent Developments and New Perspectives

“…Thus, replacement of the heavy metal catalyst with a safe and environmentally acceptable alternative is an important issue. To this end, one-pot production of PLA and its copolymers was achieved using the newly established microbial cell factory integrated by a lactatepolymerizing enzyme (LPE) (refer to section 1.2.3) [36,37].…”

“…The first indication of LA-polymerizing activity was obtained through a water-organic solvent two-phase in vitro system [36,37]. The activity towards LA-CoA was tested in the absence and presence of 3HB-CoA using representative PHA synthases belonging to the four classes of natural PHA synthases, together with three engineered (PhaC1 Ps mutants) from Pseudomonas sp.…”

Poly(Lactic Acid)-Based Biomaterials: Synthesis, Modification and Applications

“…The advantages and disadvantages of the PLA synthesis methods mentioned above are summarized in Table 2. In the bio-process, the LA monomer is converted into LA-CoA ,which is recognized by the LA-polymerizing enzyme recruited from microbial PHA synthase (Tajima et al, 2009 …”