STUDIES ON CA2-AMYLASE( BINDING OF THERMOSTABLE ALPHA)

It was determined that alpha-amylase contained ten Ca2+. Resulted from the study of stability and activity of Ca2+-free alpha-amylase after adding Ca2+, the first eight Ca2+ related to catalyt ic function of th e enzyme, the other two Ca2+ made the structure of enzyme stable. Acco rding to the CD and fluorescence spectra of alpha-amylase at room temp erature, no significant change of the enzyme structure was observed. F urthermore, according to the CD spectra of alpha-amylase after adding Ca2+ (heated at 90 degrees C for 15 min), some alpha-helix structures of the enzyme still existed. Fluorescence spectra of alpha-amylase at 90 degrees C for 15 min also showed that enzyme kept the conformation maximum stability when the Ca2+-free alpha-amylase was binding to 10 C a2+. All the results indicated that the dependence of enzyme conformat ion on Ca2+ was low.