不同pH对蛋清溶菌酶形成淀粉样纤维的影响

doi:10.16431/j.cnki.1671-7236.2021.04.035

Abstract

Abstract: The aim of this study was to investigate the effect of pH conditions on amyloid fibrils formation.Hen egg-white lysozyme (HEWL) was used as the model protein in this study.HEWL was prepared in different pH conditions,such as pH 2.0,6.5,7.5 and 8.0.Then HEWL samples were incubated at (57.0±0.1) ℃ for 8 days to aggregate into amyloid fibrils.Morphology was imaged by transmission electron microscopy.Thioflavin T (ThT) and Congo red dye methods were used to detect the growth of HEWL aggregates,respectively.8-anilino-1-naphthalenesulfonic acid (ANS) fluorescence was used to quantify the hydrophobicity of formed HEWL fibrils.Circular dichroism was explored to measure the secondary structural transition and forecast the β-sheet content.The results showed that HEWL at pH 2.0 solution produced large rod-shaped amyloid fibrils under transmission electron microscopy after incubating for 8 days,and ThT fluorescence results showed that the fibrils quantity at pH 2.0 were higher than other pH groups 2.0 groups (P<0.01),and the growth of amyloid fibrils was time-dependent.Furthermore,Congo red detected both the shift of absorption peak from 490 nm to 510 nm and characteristic shoulder peak at 540 nm,hydrophobicity and β-sheet content were significantly increased,with β-sheet content was increased from 6.1% of native HEWL to 37.6% of pH 2.0 HEWL.pH 6.5 group produced very fewer amyloid fibrils only under transmission electron microscopy.pH 7.5 group produced no visible amyloid fibrils,while visible abundant spherical or rod-shaped aggregated proteins appeared under transmission electron microscopy.However,pH 8.0 group produced no fibrils and aggregated proteins for any detected methods.The results suggested that HEWL easily aggregated into amyloid fibrils at pH 2.0 with the highest hydrophobicity and structural conversion,which provided basic data for the mechanisms of fibrillary aggregation of prion disease and other amyloidosis.

Key words: amyloid fibrils; prion disease; hen egg-white lysozyme; secondary structural transition; β-sheet

CLC Number:

S852.34

LI Ying, BAI Yu, FENG Zili. Effect of Different pH Conditions on Amyloid Fibrils Formation of Hen Egg-white Lysozyme[J]. China Animal Husbandry and Veterinary Medicine, 2021, 48(4): 1466-1471.

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Effect of Different pH Conditions on Amyloid Fibrils Formation of Hen Egg-white Lysozyme

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