Coconut fiber (Coco nucifera L.) as support for immobilization of horsearadish peroxidase (HRP)

Coconut fiber is one of the principal residues generated in Northeastern Brazil. Thus the development of bioproducts that use this residue as component is of great importance for the industrial sector. In this work was evaluated the potential use coconut fiber as support for immobilization of the horseradish peroxidase (HRP), an enzyme of great importance in the clinical-diagnostic sector. The effect of alkaline pre-treatment on the fiber was evaluated: HRP was immobilized by physical adsorption and covalent bonding techniques in pre-treated residue with NaOH (5 M) and untreated coconut fiber. The enzyme loading used was 8 mg HRP/g of support and results expressed in terms of immobilization efficiency (IE %). Best results occurred with the pre-treated coconut fiber as support (IE: 85% - ADS, LC), while the untreated coconut fiber provided  60% (ADS, LC). The results suggest the need the pre-treating the fiber for subsequent use as a support for immobilization of HRP. These results converge to those obtained from Fourier Transform Infrared Spectroscopy (FTIR) analysis of coconut fiber without alkali treatment, that showed characteristic bands of the hemicelluloses and lignin at 1728 cm^-1 and 1607 cm^-1, respectivelly . For the pretreated fiber it was found a changing on the lignin band to 1593 cm^-1 and absence of the band at 1728 cm^-1. This result suggests the alkaline treatment deconstructs the fiber lignocellulosic increasing the accessibility of the enzyme to support reactive groups.