关键词: &alpha, －淀粉酶, Ca²⁺, 构象

Abstract: It was determined that α-amylase contained ten Ca²⁺.Resulted from the study of stability and activity of Ca²⁺-free α-amylase after adding Ca²⁺, the first eight Ca²⁺related to catalytic function of the enzyme, the other two Ca²⁺made the structure of enzyme stable. According to the CDand fluorescence spectra of α-amylase at room temperature, no significant change of the enzyme structure was observed. Furthermore, according to the CDspectra of α-amylase after adding Ca²⁺(heated at 90 ℃ for 15 min), some α-helix structures of the enzyme still existed. Fluorescence spectra of α-amylase at 90 ℃ for 15 min also showed that enzyme kept the conformation maximum stability when the Ca²⁺-free α-amylase was binding to 10 Ca²⁺.All the results indicated that the dependence of enzyme conformation on Ca²⁺was low.

Key words: α-Amylase,Ca²⁺, Conformation