De Mithu, Das Kali P, Chakrabartty P K
Department of Microbiology, Bose Institute, P1/12 C.I.T. Scheme VII-M, Kolkata-700 054.
Indian J Biochem Biophys. 2005 Oct;42(5):287-94.
Alpha-Amylase (EC 3.2.1.1) was purified to homogeneity (specific activity 58,000 micromole min(-1) mg protein(-1)) from the culture filtrate of Bacillus amyloliquefaciens NCIM 2829. Its molecular mass was found to be 67.5 kDa. The activity of the enzyme increased by almost 50% in the presence of Co+2 ion. Hg2+ and Cu2+ acted as strong inhibitors of the enzyme. The tryptophan moities of the enzyme were fairly protected from the aqueous environment. However, the globular interior of the protein was somewhat loosely packed. The protein had nearly an equal amount of alpha-helical and beta-sheet structure in dilute solution. In concentrated solution, its secondary structure had a higher proportion of beta-sheet at the expense of some random coil structure. The protein showed a molten globule state at a low concentration of chaotropic agent. The denaturation profile of the protein showed no cooperativity. Co2+ enhanced the structural stability of the enzyme.
从解淀粉芽孢杆菌NCIM 2829的培养滤液中纯化出了α-淀粉酶（EC 3.2.1.1），使其达到了均一性（比活性为58,000微摩尔·分钟⁻¹·毫克蛋白质⁻¹）。发现其分子量为67.5 kDa。在Co²⁺离子存在的情况下，该酶的活性几乎提高了50%。Hg²⁺和Cu²⁺是该酶的强抑制剂。该酶的色氨酸部分受到了较好的保护，免受水环境的影响。然而，蛋白质的球状内部结构有些松散。在稀溶液中，该蛋白质具有几乎等量的α-螺旋和β-折叠结构。在浓溶液中，其次级结构中β-折叠的比例较高，部分无规卷曲结构减少。在低浓度的离液剂中，该蛋白质呈现出熔球状态。该蛋白质的变性曲线没有协同性。Co²⁺增强了该酶的结构稳定性。
