Biomacromolecular Journal Immobilization of Subtilisin Carlsberg on Modified Silica Gel by Cross-linking and Covalent Binding Methods

ABSTRACT Proteases are important enzymes that their role in various industries is undeniable. However, keeping enzymes stable during its activity in harsh conditions is so important. In this study, protease enzyme was immobilized on the porous silica particles and its stability in different temperatures and pHs was evaluated. First silica particles were aminated by 3-aminopropyltriethoxysilane then the protease enzyme was immobilized on the modified silica by glutaraldehyde cross-linking method and the immobilized enzyme's activity was maintained for more than 40 days. Measuring the free subtilisin carlsberg enzyme activity and immobilized enzyme was performed according to the Lowry method. In another part, the effects of different pHs and temperatures on free and immobilized protease were evaluated. The immobilized protease activity was measured in temperature range between 25-75 C and pH range 6.5-12. The absorption was read in 660 nm. It is shown that the optimum temperature for immobilizaed enzyme is 50 °C. The results showed that immobilized protease is more stable than free protease

Biomacromolecular Journal Evaluation of Immobilized Bacteriorhodopsin's Function by Laser Irridiation

ABSTRACT Bacteriorhodopsin (BR) is a retinal protein that is a light-driven proton pump and has an important role in photosynthesis in archaebacterium Halobacterium salinarum. The BR molecule absorbs light and photochemical changes occur in it, and different intermediates will be produced in its photochemical cycle that some of them like P and Q intermediates have a long half-life. There have been many efforts to immobilize BR for constructing data storage devices. In this study the BR suspension-contained film has been immobilized on a polycarbonate and the effects of green and red lasers on it (in different times and temperatures) have been investigated by UV spectrophotometer method, The modified surfaces were characterized by ATR-FTIR and AFM techniques. The results show that with used condition for immobilization of BR on polycarbonate, the 0 and 1 bite that relate to BR and P, Q intermediate, are formed. The red and green lasers convert BR to O and, P or Q intermediates respectively that could be used instead of 0 and 1 bites in popular compact disks