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关键词： Circular dichroism   Fluorescence   Molecular docking   Myoglobin   Quinoline yellow   HUMAN SERUM-ALBUMIN   HUMAN HEMOGLOBIN PROTEINS   BINDING   DRUGS   FLUORESCENCE   TARTRAZINE   HERBICIDES   STATE   ACID   FTIR  

摘要： Protein aggregation leads to vast conformational changes and plays a key role in the pathogenesis of various neurodegenerative diseases including Alzheimer's and Parkinson's. In the current piece of work, we have explored the interaction of quinoline yellow(QY) with myoglobin (Mb) at two different pH (3.5 and 7.4). Various spectroscopic techniques such as turbidity, Rayleigh light scattering (RLS), UV-Vis absorbance, fluorescence resonance energy transfer (FRET), far UV-CD along with transmission electron microscopy (TEM) and molecular docking have been utilized to characterize dye-induced aggregation in Mb. Binding results showed that interaction between QY and myoglobin is spontaneous and static in nature with high K-SV value of 2.14 x 10(4) M-1. On the other hand, thermodynamics studies (Delta H & Delta S) revealed that complex formation was driven by hydrogen and Van der Walls forces. Molecular docking analysis showed strong binding affinity (K-d = 4.95 x 10(4) M-1) between QY and Mb at Pro100, Ile101, Lys102, Glu105, Glu136, Arg139, Lys140, and Ala143 residues. The intrinsic fluorescence and circular dichroism studies indicated that QY induced conformational changes in Mb at pH 3.5. Turbidity and RLS studies showed aggregation of Mb in the presence of QY (0.2-5 mM). Moreover, kinetics data revealed nucleation independent aggregation of myoglobin in the presence of QY. TEM analysis further established amorphous nature of Mb aggregate induced by QY. At pH (7.4), QY was unable to induce aggregation in myoglobin; it might be due to repulsive nature of negatively charged dye and myoglobin or partially altered states of protein could be pre-requisite for binding and aggregation. (C) 2019 Published by Elsevier B.V.

关键词： 食品添加剂   食品安全   罗云波   科学认知  

摘要： 前段时间,注册地在香港的'反食品添加剂联盟'在北京举行活动。该联盟提出,为了国人健康,食品行业应杜绝食品添加剂。'这样的组织能堂而皇之地在北京国际展览中心开论坛和展会,还有人给它站台,确实匪夷所思。这是一场闹剧,值得反思。'在中国农业大学组织召开的科学认知食品安全和食品添加剂研讨会上.

关键词： 锥形瓶   玻璃珠   新鲜蔬菜   MPN   稀释度   速冻饺子   无菌吸管   大肠杆菌   大肠菌群  

摘要： 在食品安全问题中,大肠杆菌是污染食品的重要指标,其能够反映食品卫生情况及推测是否存在肠道致病菌的可能性。下面笔者以GB4789.3-2010《食品安全国家标准食品微生物学检验大肠菌群计数》作为参考方法,利用MPN法及平板计数法开展对新鲜蔬菜和速冻饺子中大肠杆菌检测的实验。