Rudeekulthamrong Prakarn, Kaulpiboon Jarunee
Department of Biochemistry, Phramongkutklao College ofMedicine, Phramongkutklao Hospital, Bangkok, Thailand.
J Med Assoc Thai. 2012 Jan;95 Suppl 1:S102-8.
The aim of the study was to evaluate the inhibitory kinetics of a novel cellobiose-containing tetrasaccharide on human salivary alpha-amylase (HSA).
Synthesis of cellobiose-containing tetrasaccharide was catalyzed by Paenibacillus sp. All CGTase using beta-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.
In vitro activity of human salivary alpha-amylase showed the optimum pH and temperature at 7.0 and 37 degrees C, respectively. The effects of metal ions, protective chemicals and saccharides on alpha-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 HgCI2, alpha-cyclodextrin (alpha-CD) and synthetic cellobiose-containing tetrasaccharide. Chemicals often used as protective substance for enzyme such as beta-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 alpha-amylase activity. Its inhibition kinetic was performed and found that cellobiose-containing tetrasaccharide was a competitive inhibitor with a Ki value of 7.89 microM.
Inhibition kinetic of a cellobiose-containing tetrasaccharide on alpha-amylase activity was competitive type with Ki value of 7.89 microM. In addition, these results will be a basic knowledge in controlling alpha-amylase actions that have influence on blood glucose level of trial animal and human further
本研究旨在评估一种新型含纤维二糖的四糖对人唾液α-淀粉酶（HSA）的抑制动力学。
在最佳条件下，以β-环糊精为供体、纤维二糖为受体，由芽孢杆菌属的所有环糊精葡萄糖基转移酶催化合成含纤维二糖的四糖。通过高效液相色谱法分析反应混合物，并对所得含纤维二糖的四糖进行抑制动力学研究。
人唾液α-淀粉酶的体外活性显示其最适pH值和温度分别为7.0和37℃。研究了金属离子、保护剂和糖类对α-淀粉酶活性的影响，发现10 mM浓度的氯化钙和氯化钠可增强酶活性。相比之下，10 mM的氯化汞、α-环糊精（α-CD）和合成的含纤维二糖的四糖可显著抑制酶活性。常用于酶保护的物质如β-巯基乙醇、乙二胺四乙酸或在酶纯化过程中用作杀菌剂的叠氮化钠（NaN3）对该酶的活性没有影响。由于含纤维二糖的四糖对α-淀粉酶活性有明显抑制作用。对其抑制动力学进行了研究，发现含纤维二糖的四糖是一种竞争性抑制剂，Ki值为7.89 microM。
含纤维二糖的四糖对α-淀粉酶活性的抑制动力学为竞争性类型，Ki值为7.89 microM。此外，这些结果将为进一步控制对实验动物和人类血糖水平有影响的α-淀粉酶作用提供基础知识。
