title: Sequencing microbial copolymers of 3-hydroxybutyric and 3-mercaptoalkanoic acids by NMR, electrospray ionization mass spectrometry, and size exclusion chromatography NMR.
abstract: Copolymers of 3-hydroxybutyrate (3HB) and 3-mercaptopropionate (3MP) or 3-mercaptobutyrate (3MB) units and minor amounts of 3-hydroxypropionate (3HP), 3-hydroxyvalerate (3HV), or 3-mercaptovalerate (3MV) were investigated regarding their microstructure by NMR, electrospray ionization mass spectrometry, and size exclusion chromatography NMR. These copolymers were produced by Ralstonia eutropha strain H16 when cells were cultivated in a mineral salts medium with gluconate as a carbon source for growth and 3MP or 3MB as precursor substrates for incorporation of 3-mercaptoalkanoates. Mass spectrometry analysis of partially methanolyzed or pyrolyzed samples proved the presence of true copolymers or terpolymers. (13)C NMR spectroscopy of intact polymer samples, with values of average block length and degree of randomness deviating from a random sequence model, suggested microblock structures; however, composition analysis by (1)H NMR of fractions obtained by size exclusion chromatography showed significant variations with molecular weight, revealing the presence of blends of poly(3HB-co-3MP-co-3HP) or poly(3HB-co-3MB) with poly(3HB). The experimental NMR carbonyl dyad signal intensities were satisfactorily matched by a random sequence model when the presence of poly(3HB) was taken into account.
authors.affiliation: Istituto di Chimica e Tecnologia dei Polimeri, Consiglio Nazionale delle Ricerche, Viale A. Doria 6, 95125 Catania, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Impallomeni
authors.forename: Alexander
authors.initials: A
authors.lastname: Steinbüchel
authors.forename: Tina
authors.initials: T
authors.lastname: Lütke-Eversloh
authors.forename: Tony
authors.initials: T
authors.lastname: Barbuzzi
authors.forename: Alberto
authors.initials: A
authors.lastname: Ballistreri
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000737:chemistry; D001671:Biochemistry / Q000379:methods*; D002845:Chromatography / Q000379:methods*; D020118:Cupriavidus necator; D006885:Hydroxybutyrates / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D013058:Mass Spectrometry; D008697:Methane / Q000737:chemistry; D008956:Models, Chemical; D008968:Molecular Conformation; D011091:Polyesters / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D006885:Hydroxybutyrates; D011091:Polyesters; D011108:Polymers; D013438:Sulfhydryl Compounds; D008697:Methane; D020155:3-Hydroxybutyric Acid