Zare H, Moosavi-Movahedi A A, Salami M, Sheibani N, Khajeh K, Habibi-Rezaei M
Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran; Estahban Fig Research Station, Fars Agricultural and Natural Resources Research and Training Center, AREEO, Shiraz, Iran.
Institute of Biochemistry and Biophysics (IBB), University of Tehran, Tehran, Iran; Center of Excellence in Biothermodynamics (CEBiotherm), University of Tehran, Tehran, Iran.
Int J Biol Macromol. 2016 Mar;84:464-71. doi: 10.1016/j.ijbiomac.2015.12.009. Epub 2015 Dec 21.
The fig's ficin is a cysteine endoproteolytic enzyme, which plays fundamental roles in many plant physiological processes, and has many applications in different industries such as pharmaceutical and food. In this work, we report the inhibition and activation of autolysis and structural changes associated with reaction of ficin with iodoacetamide and tetrathionate using high-performance liquid chromatography (HPLC), ultra filtration membrane, and dynamic light scattering (DLS) methods. The ficin structural changes were also determined using UV-absorption, circular dichroism (CD), fluorescence spectroscopy, and differential scanning calorimetry (DSC) techniques. These techniques demonstrated that iodoacetamide completely inhibited ficin autolysis, which was irreversible. However, tetrathionate partially and reversibility inhibited its autolysis. The ficin structural changes with two synthetic inhibitors were associated with secondary structural changes related to decreased alpha-helix and increased beta sheet and random coil conformations, contributing to its aggregation.
无花果的无花果蛋白酶是一种半胱氨酸内切蛋白酶，在许多植物生理过程中发挥着重要作用，并且在制药和食品等不同行业有诸多应用。在这项工作中，我们使用高效液相色谱（HPLC）、超滤膜和动态光散射（DLS）方法，报道了无花果蛋白酶与碘乙酰胺和连四硫酸盐反应相关的自溶抑制与激活以及结构变化。还使用紫外吸收、圆二色性（CD）、荧光光谱和差示扫描量热法（DSC）技术测定了无花果蛋白酶的结构变化。这些技术表明，碘乙酰胺完全抑制了无花果蛋白酶的自溶，且这种抑制是不可逆的。然而，连四硫酸盐部分且可逆地抑制了其自溶。两种合成抑制剂引起的无花果蛋白酶结构变化与二级结构变化有关，即α-螺旋减少、β-折叠和无规卷曲构象增加，这导致了其聚集。
