Objective: The aim of the study was to evaluate the inhibitory kinetics of a novel cellobiose containing tetrasaccharide on human salivary α-amylase (HSA).
Material and Method: Synthesis of cellobiose-containing tetrasaccharide was catalyzed by Paenibacillus sp. A11 CGTase using β-CD as a donor and cellobiose as an acceptor under the optimal conditions. The reaction mixture was analyzed by HPLC and a cellobiose-containing tetrasaccharide obtained was studied for its inhibitory kinetics.
Results: In vitro activity of human salivary α-amylase showed the optimum pH and temperature at 7.0 and 37°C, respectively. The effects of metal ions, protective chemicals and saccharides on α-amylase activity, they were found that 10 mM concentration of CaCl2 and NaCl enhanced the enzyme activity. In contrast, the enzyme activity was significantly inhibited by 10 mM of HgCl2, α-cyclodextrin (α-CD) and synthetic cellobiose containing tetrasaccharide. Chemicals often used as protective substance for enzyme such as β-mercaptoethanol, EDTA or used as fungicide during enzyme purification (NaN3) had no effect on the activity of this enzyme. As a cellobiose-containing tetrasaccharide was shown to have a pronounce inhibition on α-
amylase activity. Its inhibition kinetic was performed and found that cellobiose-containing tetrasaccharide was a competitive inhibitor with a Ki value of 7.89 μM.
Conclusion: Inhibition kinetic of a cellobiose-containing tetrasaccharide on α-amylase activity was competitive type with Ki value of 7.89 μM. In addition, these results will be a basic knowledge in controlling α-amylase actions that have influence on blood glucose level of trial animal and human further.

Keywords: Beta-cyclodextrin (β-CD), Cellobiose, Enzyme inhibitor, Human salivary α-amylase (HSA), Tetrasaccharide