1. Substrate specificities of cutinases on aliphatic–aromatic polyesters and on their model substrates
- Author
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Melanie Bonnekessel, Klaus Bleymaier, Ulf Kueper, Veronika Perz, Georg M. Guebitz, Doris Ribitsch, and Carsten Sinkel
- Subjects
0301 basic medicine ,Cutinase ,Polyesters ,Phthalic Acids ,Sordariales ,Bioengineering ,Biodegradable Plastics ,02 engineering and technology ,Substrate Specificity ,Fungal Proteins ,03 medical and health sciences ,chemistry.chemical_compound ,Hydrolysis ,Bacterial Proteins ,Enzymatic hydrolysis ,Polymer chemistry ,Transition Temperature ,Organic chemistry ,Molecular Biology ,Soil Microbiology ,Benzoic acid ,Terephthalic acid ,Adipic acid ,Polyethylene Terephthalates ,General Medicine ,021001 nanoscience & nanotechnology ,Actinobacteria ,Polyester ,Kinetics ,Phthalic acid ,Biodegradation, Environmental ,030104 developmental biology ,chemistry ,0210 nano-technology ,Carboxylic Ester Hydrolases ,Biotechnology - 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.
- Published
- 2016