title: The effect of Arg on the structure perturbation and chaperone activity of α-crystallin in the presence of the crowding agent, dextran.
abstract: α-Crystallin is a protein that is expressed at high levels in all vertebrate eye lenses. It has a molecular weight of 20 kDa and is composed of two subunits: αA and αB. α-Crystallin is a member of the small heat shock protein (sHsps) family that has been shown to prevent protein aggregation. Small molecules are organic compounds that have low molecular weight (<800 Da). Arginin (Arg) is a small molecule and has been shown to prevent protein aggregation through interaction with partially folded intermediates. In this study, the effect of Arg on the chaperone activity of α-crystallin in the presence of dextran, as a crowding agent, against ordered and disordered aggregation of different target proteins (α-lactalbumin, ovotransferrin, and catalase) has been investigated. The experiments were done using visible absorption spectroscopy, ThT-binding assay, fluorescence spectroscopy, and CD spectroscopy. The results showed that in amorphous aggregation and amyloid fibril formation, both in the presence and absence of dextran, Arg had a positive effect on the chaperone action of α-crystallin. However, in the presence of dextran, the effect of Arg on the chaperone ability of α-crystallin was less than in its absence. Thus, our result suggests that crowding interior media decreases the positive effect of Arg on the chaperone ability of α-crystallin. This is a very important issue, since we are trying to find a mechanism to protect living cells against the toxic effect of protein aggregation.
authors.affiliation: Department of Biology, Faculty of Science, University of Sistan and Baluchestan, Zahedan, Iran, arezou@chem.usb.ac.ir.
authors.forename: Arezou
authors.initials: A
authors.lastname: Ghahghaei
authors.forename: Somaye
authors.initials: S
authors.lastname: Mohammadian
mesh_terms: D001120:Arginine / Q000737:chemistry / Q000378:metabolism*; D002374:Catalase / Q000737:chemistry; D002942:Circular Dichroism; D003207:Conalbumin / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry*; D007768:Lactalbumin / Q000737:chemistry; D018832:Molecular Chaperones / Q000737:chemistry / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D038201:alpha-Crystallins / Q000737:chemistry / Q000502:physiology*
chemical_list: D003911:Dextrans; D018832:Molecular Chaperones; D038201:alpha-Crystallins; D003207:Conalbumin; D007768:Lactalbumin; D001120:Arginine; D002374:Catalase