Immobilization of the Alkaline Phosphatase on Collagen Surface via Cross-Linking Method

Background: Collagen, the most abundant protein in the human body, and as an extracellular matrix protein, has an important role in the fiber formation. This feature of the collagen renders  establishment of the structural skeleton in tissues. Regarding specific features associated with the collagen, such as, formation of the porous structure, permeability and hydrophilicity, it can also be used as a biocompatible matrix in the enzyme engineering. Objectives: The aim of the present study was to investigate the application of the type I collagen as a matrix for alkaline phosphatase immobilization using cross-linking method. Material and Methods: The Alkaline phosphatase was covalently immobilized on collagen matrix by using 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC). The source of the alkaline phosphatase was from the bovine intestinal mucous. After that, the activity of the immobilized enzyme was assayed under different experimental conditions. Results: The optimum pH was similar to that of the free enzyme, whereas the optimum temperature and thermal stability were shown some increments. The surface topography of the collagen matrix containing immobilized enzyme and ALP (Alkaline phosphatase) deficient was investigated by Atomic-force microscopy (AFM). Images that have been obtained applying AFM show significant differences between uncovered and immobilized enzyme- matrix surface topography. Conclusions: Our findings suggest that type I collagen can be utilized as a matrix for alkaline phosphatase immobilization via cross-linking method.