Decreased subunit exchange of heat-treated lens alpha A-crystallin.
alpha A-Crystallin high-molecular-weight (HMW) aggregates were prepared by preheating at 80-90 degrees C and studied using spectroscopic measurements. Conformational differences were suggested based on data of increased bis-ANS (4,4(')-dianilino-1,1(')-binaphthalene-5,5(')-disulfonic acid) and ThT (thioflavin T) fluorescence as well as increased far-UV and decreased near-UV circular dichroism (CD). These results indicated that HMW aggregated alpha-crystallin was more hydrophobic than the native alpha-crystallin, possibly resulting from partial unfolding of alpha-crystallin. The two cysteines in alpha A-crystallin were mostly oxidized in HMW aggregates. The effects of HMW aggregation on the dynamic structure were studied with fluorescence resonance energy transfer; subunit exchange became slower. These results strongly suggest that HMW alpha A-crystallin aggregates result from exposure of buried beta-pleated sheets and increased hydrophobic interaction.
Liang
Jack J-N
JJ
Department of Ophthalmology, Center for Ophthalmic Research, Brigham and Women's Hospital, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA. jliang@rics.bwh.harvard.edu
Fu
Ling
L
D002942:Circular Dichroism; D003459:Crystallins / Q000737:chemistry*; D005456:Fluorescent Dyes; D006358:Hot Temperature; D007908:Lens, Crystalline / Q000737:chemistry*; D008970:Molecular Weight; D011487:Protein Conformation; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry
D003459:Crystallins; D005456:Fluorescent Dyes; D021122:Protein Subunits; D011994:Recombinant Proteins