Structural studies on beta H-crystallin from bovine eye lens.
Bovine lens beta H-crystallin, isolated at pH 6.7, undergoes reversible dissociation into dimers and an intermediate size of oligomer (peak A) at pH 5.4. Peak A is enriched in the beta B1 subunit but lacks beta B2, whereas beta B2 is a major component of the dimers. A method for isolation of beta B1 from peak A is described. The pH dependence of the dissociation-reassociation suggests that histidines on the surface of the dimers become buried in the assembly of beta H-crystallin. The positions of the four histidines on the surface of the compact domains of each subunit of the beta B2 homodimer are shown. The beta B1-enriched oligomer has a much lower solubility compared with the beta B2 containing beta H-crystallin. It is possible that beta B2 plays a role in solubilizing beta-crystallin aggregates.
Bateman
O A
OA
Department of Crystallography, Birkbeck College, London, U.K.
Slingsby
C
C
D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D003459:Crystallins / Q000302:isolation & purification*; D006639:Histidine / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008970:Molecular Weight; D012995:Solubility
D003459:Crystallins; D046911:Macromolecular Substances; D006639:Histidine