title: Biosynthesis and characterization of polyhydroxyalkanoate block copolymer P3HB-b-P4HB.
abstract: Polyhydroxyalkanoates (PHA) synthesis genes phbC and orfZ cloned from Ralstonia eutropha H16 were transformed into beta-oxidation weakened Pseudomonas putida KTOY08ΔGC, a mutant of P. putida KT2442. The recombinant P. putida strain termed KTHH06 was able to produce a short-chain-length PHA block copolymer consisting of poly(3-hydroxybutyrate) (P3HB) as one block and poly(4-hydroxybutyrate) (P4HB) as another block. One-dimensional and two-dimensional nuclear magnetic resonance (NMR) clearly indicated the polymer was a diblock copolymer consisting of 20 mol % P3HB as one block and 80 mol % P4HB as another one. Differential scanning calorimetric (DSC) showed that P3HB block melting temperatures (T(m)) in the block copolymer P3HB-b-P4HB was shift to low temperature compared with homopolymer P3HB and a blend of P3HB and P4HB. The block copolymer with a number average molecular weight of 50000 Da and a polydispersity of 3.1 demonstrated a better yield and tensile strength compared with that of its related random copolymer and blend of homopolymers of P3HB and P4HB.
authors.affiliation: MOE Key Lab of Protein Sciences, Department of Biological Sciences and Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Die
authors.initials: D
authors.lastname: Hu
authors.forename: Ah-Leum
authors.initials: AL
authors.lastname: Chung
authors.forename: Lin-Ping
authors.initials: LP
authors.lastname: Wu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wu
authors.forename: Jin-Chun
authors.initials: JC
authors.lastname: Chen
authors.forename: Guo-Qiang
authors.initials: GQ
authors.lastname: Chen
mesh_terms: D015107:4-Butyrolactone / Q000378:metabolism; D000217:Acyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology; D001673:Biodegradation, Environmental; D002152:Calorimetry, Differential Scanning; D003001:Cloning, Molecular; D020118:Cupriavidus necator / Q000201:enzymology / Q000235:genetics*; D005827:Genetics, Microbial / Q000379:methods*; D006885:Hydroxybutyrates / Q000378:metabolism; D008970:Molecular Weight; D019906:Nuclear Magnetic Resonance, Biomolecular; D010957:Plasmids; D011091:Polyesters / Q000378:metabolism; D054813:Polyhydroxyalkanoates / Q000032:analysis / Q000096:biosynthesis*; D016958:Pseudomonas putida / Q000201:enzymology / Q000235:genetics*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D013718:Tensile Strength; D023822:Tissue Engineering / Q000379:methods*; D014169:Transformation, Bacterial; D000094122:Polyhydroxybutyrates
chemical_list: D015107:4-Butyrolactone; D000217:Acyltransferases; D001426:Bacterial Proteins; D001672:Biocompatible Materials; D006885:Hydroxybutyrates; D011091:Polyesters; D054813:Polyhydroxyalkanoates; D011994:Recombinant Proteins; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates