Physicochemical characterization of beta-crystallins from bovine lenses: hydrodynamic and aggregation properties.
A detailed investigation of the hydrodynamic and aggregation behaviors has been made on the beta-crystallins of bovine lens. Results from this study indicated that beta H (high-molecular-weight beta-crystallin) and beta L (low-molecular-weight beta-crystallin) exhibited considerable heterogeneity in their native structures and subunit polypeptides. Low-speed sedimentation equilibrium showed a heterogeneous paucidisperse system in each beta-crystallin fraction. Viscosity and circular dichroism studies pointed to a compact and globular shape and the presence of beta-sheet and beta-turns in these crystallins. Dissociation of beta H by urea and guanidinium HCl followed by reassociation during gel-filtration chromatography produced an elution pattern with two fractions corresponding to beta L crystallin and high-molecular-weight aggregates without the formation of native beta H. By contrast, under similar treatment, about 60% beta L reassociated into the correct native structure and the rest into high-molecular-weight fractions. Amino acid analyses of beta H and beta L and their corresponding subunit polypeptides demonstrated the close similarity of these crystallins. Trace element analyses indicated that both Ca and Mg are present in beta H and beta L crystallins and may be involved in maintaining the native quarternary structures of these proteins.
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China.
S H
SH
Chiou
P
P
Azari
M E
ME
Himmel
H K
HK
Lin
W P
WP
Chang
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000302:isolation & purification; D000818:Animals; D002417:Cattle; D002850:Chromatography, Gel; D002942:Circular Dichroism; D003459:Crystallins / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D007908:Lens, Crystalline / Q000032:analysis*; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification; D011487:Protein Conformation; D014461:Ultracentrifugation
D000596:Amino Acids; D003459:Crystallins; D010455:Peptides