Department of Biochemistry, Faculty of Medicine, Aligarh Muslim University, Aligarh, India.
Department of Biochemistry, Faculty of Medicine, Aligarh Muslim University, Aligarh, India.
Int J Biol Macromol. 2018 Apr 1;109:896-906. doi: 10.1016/j.ijbiomac.2017.11.069. Epub 2017 Nov 11.
Fructose is a reducing and highly lipogenic sugar that has unique metabolic effects in the liver. Non-enzymatic fructosylation of proteins generates advanced glycation end products (AGEs). Human serum albumin (HSA) may undergo fructosylation vis-à-vis AGEs formation. High fructose consumption may lead to structurally altered and functionally compromised fructosylated-HSA-AGEs, which can cause damage to hepatocytes resulting in hepatic macro- and microvesicular steatosis. In this study, HSA was incubated with varying concentrations of fructose for 10days and the induced changes were studied. Fructosylated-HSA exhibited hyperchromicity, increased AGE-specific fluorescence, quenching of tryptophan fluorescence and increased melting temperature. Nε-[carboxymethyl]-lysine (CML), was detected by liquid chromatography mass spectrometry (LC-MS). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) results showed decreased mobility in fructosylated-HSA. Perturbations in secondary and tertiary structure were revealed by fourier transform-infrared spectroscopy (FT-IR), supported by far- and near-UV circular dichroism (CD). Dynamic light scattering (DLS) and Matrix-Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) mass spectrometry studies suggested increase in molecular mass of fructosylated-HSA. Amyloidogenic aggregates were confirmed from Congo red, Thioflavin T assay and Scanning electron microscope (SEM). These investigations confirmed the structural alterations in fructosylated-HSA and warrants further study to probe the role of fructosylated-HSA-AGEs in hepatopathy vis-à-vis fatty liver diseases.
果糖是一种具有还原作用且高度生脂的糖，在肝脏中有独特的代谢作用。蛋白质的非酶促果糖基化会产生晚期糖基化终产物（AGEs）。人血清白蛋白（HSA）可能会通过 AGEs 的形成发生果糖基化。大量摄入果糖可能导致结构改变和功能受损的果糖基化-HSA-AGEs，从而对肝细胞造成损伤，导致肝大泡和微泡性脂肪变性。在这项研究中，将 HSA 与不同浓度的果糖孵育 10 天，并研究了诱导的变化。果糖基化-HSA 表现出增色性、增加的 AGE 特异性荧光、色氨酸荧光猝灭和增加的熔点。通过液相色谱-质谱联用（LC-MS）检测 Nε-[羧甲基]-赖氨酸（CML）。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）结果表明果糖基化-HSA 的迁移率降低。傅里叶变换-红外光谱（FT-IR）显示二级和三级结构发生了扰动，远和近紫外圆二色性（CD）也支持了这一点。动态光散射（DLS）和基质辅助激光解吸电离飞行时间（MALDI-TOF）质谱研究表明，果糖基化-HSA 的分子量增加。从刚果红、硫代黄素 T 测定和扫描电子显微镜（SEM）证实了淀粉样纤维的聚集。这些研究证实了果糖基化-HSA 的结构改变，并需要进一步研究以探讨果糖基化-HSA-AGEs 在肝病变，特别是在脂肪性肝病中的作用。
