Department of Biochemistry, Faculty of Life Sciences, AMU, Aligarh, U.P., 202002, India.
Department of Biochemistry, Faculty of Life Sciences, AMU, Aligarh, U.P., 202002, India.
Int J Biol Macromol. 2018 Jan;106:917-929. doi: 10.1016/j.ijbiomac.2017.08.086. Epub 2017 Aug 24.
Glycation induced advanced glycation end products (AGEs) of proteins formed as a result of Maillard reaction is currently at the heart of a number of pathological conditions. The formation of chemically stable AGEs can permanently alter protein structure and function; hence can serve as an implication in long term complications. Cystatins with high amyloidogenic inclination are implicated in various diseases including cancer and neurodegenerative conditions. The aggregates of cystatin purified from caprine brain have been studied on addition of glucose and ribose using UV absorption, fluorescence emission, circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). In the present study AGEs have been monitored and characterized. CBC was incubated for varying time intervals up to 41days in the presence of 17 and 100mM each of glucose and ribose. Ribose at both the concentrations was found to be more potent glycating agent as compared to glucose at these concentrations which is evident from UV and fluorescence spectroscopic studies. Altered intrinsic and high ANS fluorescence for 100mM and 17mM sugar concentrations respectively, suggested the existence of molten globule state of CBC. Glycated CBC as AGEs and aggregates were observed on day 27 and 41 respectively. Formation of AGEs was confirmed by employing AGEs specific fluorescence studies. CBC aggregates confirmed the presence of β-sheet structure as shown by far-UV CD, dye binding assay and transmission electron microscopy (TEM). Current study is of immense importance as cystatin is a potential candidate of amyloidogenic tendency and a potent endogenous regulator of thiol proteases; hence serves to be an attractive model to study amyloidogenesis of brain cysteine protease inhibitor.
糖基化诱导的蛋白质晚期糖基化终产物（AGEs）是美拉德反应的结果，目前是许多病理状况的核心。化学稳定的 AGEs 的形成可以永久改变蛋白质的结构和功能；因此可以作为长期并发症的一个暗示。具有高淀粉样倾向的胱抑素与包括癌症和神经退行性疾病在内的各种疾病有关。已经使用紫外吸收、荧光发射、圆二色性（CD）光谱和透射电子显微镜（TEM）研究了从山羊脑中纯化的胱抑素的聚集体在添加葡萄糖和核糖时的情况。在本研究中，监测和表征了 AGEs。CBC 在 17mM 和 100mM 葡萄糖和核糖的存在下，在不同的时间间隔（长达 41 天）孵育。与这些浓度下的葡萄糖相比，在这两种浓度下，核糖被发现是更有效的糖化剂，这从紫外和荧光光谱研究中可以明显看出。对于 100mM 和 17mM 糖浓度，分别为固有和高 ANS 荧光的改变，表明 CBC 存在无规卷曲状态。在第 27 天和第 41 天分别观察到糖基化的 CBC 作为 AGEs 和聚集体。通过使用 AGEs 特异性荧光研究证实了 AGEs 的形成。CBC 聚集体证实了存在β-折叠结构，如远紫外 CD、染料结合测定和透射电子显微镜（TEM）所示。目前的研究非常重要，因为胱抑素是淀粉样倾向的潜在候选物，也是硫醇蛋白酶的有效内源性调节剂；因此，它是研究脑半胱氨酸蛋白酶抑制剂淀粉样变性的有吸引力的模型。
