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Stabilizing leaf and branch compost cutinase (LCC) with glycosylation: Mechanism and effect on PET hydrolysis.

Author
Abstract
:

Cutinases are polyester hydrolases that show a remarkable capability to hydrolyze polyethylene terephthalate (PET) to its monomeric units. This revelation has stimulated research aimed at developing sustainable and green cutinase-catalyzed PET recycling methods. Leaf and branch compost cutinase (LCC) is particularly suited towards these ends given its relatively high PET hydrolysis activity and thermostability. Any practical enzymatic PET recycling application will require that the protein have kinetic stability at or above the PET glass transition temperature (Tg, i.e. 70 oC). This paper elucidates the thermodynamics and kinetics of LCC conformational and colloidal stability. Aggregation emerged as a major contributor that reduces LCC kinetic stability. In its native state, LCC is prone to aggregation owing to electrostatic interactions. Further, with increasing temperature, perturbation of LCC's tertiary structure and corresponding exposure of hydrophobic domains leads to rapid aggregation. Glycosylation was employed in an attempt to impede LCC aggregation. Owing to the presence of three putative N-glycosylation sites, expression of native LCC in Pichia pastoris resulted in the production of glycosylated LCC (LCC-G). LCC-G showed improved stability to native state aggregation while increasing the temperature for thermal induced aggregation by 10 oC. Furthermore, stabilization against thermal aggregation resulted in improved catalytic PET hydrolysis both at its optimum temperature and concentration.

Year of Publication
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2018
Journal
:
Biochemistry
Date Published
:
2018
ISSN Number
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0006-2960
DOI
:
10.1021/acs.biochem.7b01189
Short Title
:
Biochemistry
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