ABSTRACT
A comparative study was performed on limited and extensive proteolysis of mesophilic (from Bacillus amyloliquefaciens [BAA]) and thermophilic (from Bacillus licheniformis [BLA]) alpha-amylases using trypsin. As expected, the thermophilic enzyme showed greater resistance to digestion by the protease. While the catalytic potential of BLA was enhanced on proteolysis, that of BAA was diminished owing to this process. Combined with greater catalytic activity, a lower thermal stability was observed for BLA on proteolytic treatment. For both enzymes, the extent of proteolytic cleavage was reduced in the presence of various stabilizing agents. The digestion patterns are explained in terms of available information in the literature on the structure of these proteins, especially in relation to segmental mobility.
Subject(s)
alpha-Amylases/chemistry , alpha-Amylases/metabolism , Bacillus/enzymology , Catalysis , Circular Dichroism , Densitometry , Electrophoresis, Polyacrylamide Gel , Kinetics , Lysine/metabolism , Protein Binding , Temperature , Time Factors , Trypsin/pharmacologyABSTRACT
Immobilization of human erythrocyte membrane was carried out by adsorption on Fractosil, a porous form of silica. Acetylcholinesterase (AChE) was chosen as a representative membrane enzyme in this study. Dependency of adsorption on membrane concentration was determined. Positive cooperative interactions that occurred in the process of immobilization increased stability. Presence of hydrophobic ligands on derivatized Fractosil was found to enhance stability of immobilized preparations making them more effective for use in continuous catalytic transformations. It is suggested that adsorptive immobilization of membrane structures such as the human erythrocyte membrane fragments on Fractosil and other inexpensive supports may provide a convenient procedure for utilization of their catalytic potential. Such preparations may be used in diagnostic kits or for construction of biosensors.
