title: Substrate specificities of cutinases on aliphatic-aromatic polyesters and on their model substrates.
abstract: The enzymatic hydrolysis of the biodegradable polyester ecoflex and of a variety of oligomeric and polymeric ecoflex model substrates was investigated. For this purpose, substrate specificities of two enzymes of typical compost inhabitants, namely a fungal cutinase from Humicola insolens (HiC) and a bacterial cutinase from Thermobifida cellulosilytica (Thc_Cut1) were compared. Model substrates were systematically designed with variations of the chain length of the alcohol and the acid as well as with varying content of the aromatic constituent terephthalic acid (Ta). HPLC/MS identification and quantification of the hydrolysis products terephthalic acid (Ta), benzoic acid (Ba), adipic acid (Ada), mono(4-hydroxybutyl) terephthalate (BTa), mono-(2-hydroxyethyl) terephthalate (ETa), mono-(6-hydroxyhexyl) terephthalate (HTa) and bis(4-hydroxybutyl) terephthalate (BTaB) indicated that these enzymes indeed hydrolyze the tested esters. Shorter terminal chain length acids but longer chain length alcohols in oligomeric model substrates were generally hydrolyzed more efficiently. Thc_Cut1 hydrolyzed aromatic ester bonds more efficiently than HiC resulting in up to 3-fold higher concentrations of the monomeric hydrolysis product Ta. Nevertheless, HiC exhibited a higher overall hydrolytic activity on the tested polyesters, resulting in 2-fold higher concentration of released molecules. Thermogravimetry and differential scanning calorimetry (TG-DSC) of the polymeric model substrates revealed a general trend that a lower difference between melting temperature (Tm) and the temperature at which the enzymatic degradation takes place resulted in higher susceptibility to enzymatic hydrolysis.
authors.affiliation: acib - Austrian Centre of Industrial Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln, Austria.
authors.forename: Veronika
authors.initials: V
authors.lastname: Perz
authors.affiliation: acib - Austrian Centre of Industrial Biotechnology, Petersgasse 14, 8010 Graz, Austria.
authors.forename: Klaus
authors.initials: K
authors.lastname: Bleymaier
authors.affiliation: BASF SE, Carl-Bosch-Strasse 38, 67056 Ludwigshafen, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Sinkel
authors.affiliation: BASF SE, Carl-Bosch-Strasse 38, 67056 Ludwigshafen, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Kueper
authors.affiliation: BASF SE, Carl-Bosch-Strasse 38, 67056 Ludwigshafen, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Bonnekessel
authors.affiliation: acib - Austrian Centre of Industrial Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln, Austria; Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Konrad Lorenz Strasse 20, 3430 Tulln an der Donau, Austria. Electronic address: doris.ribitsch@acib.at.
authors.forename: Doris
authors.initials: D
authors.lastname: Ribitsch
authors.affiliation: acib - Austrian Centre of Industrial Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln, Austria; Institute of Environmental Biotechnology, University of Natural Resources and Life Sciences, Konrad Lorenz Strasse 20, 3430 Tulln an der Donau, Austria.
authors.forename: Georg M
authors.initials: GM
authors.lastname: Guebitz
mesh_terms: D039903:Actinobacteria / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry*; D063566:Biodegradable Plastics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002265:Carboxylic Ester Hydrolases / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry*; D006868:Hydrolysis; D007700:Kinetics; D010795:Phthalic Acids / Q000378:metabolism; D011091:Polyesters / Q000378:metabolism*; D011093:Polyethylene Terephthalates / Q000378:metabolism; D012988:Soil Microbiology; D020037:Sordariales / Q000201:enzymology*; D013379:Substrate Specificity; D044366:Transition Temperature
chemical_list: D001426:Bacterial Proteins; D063566:Biodegradable Plastics; D005656:Fungal Proteins; D010795:Phthalic Acids; D011091:Polyesters; D011093:Polyethylene Terephthalates; C472388:ecoflex; C011363:terephthalic acid; D002265:Carboxylic Ester Hydrolases; C019952:cutinase