1H‐NMR spectroscopy of bovine lens β‐crystallin

Abstract

1H‐NMR spectroscopic studies of bovine eye lens β‐crystallin aggregates (dimer, trimer and octomer) are presented. The NMR spectra for all three β‐crystallin aggregates are dominated by resonances from the βB2 subunit, particularly from the N‐ and C‐terminal extensions of this subunit. Resonances from other β subunits, which all have terminal extensions, are, in general, absent from spectra of the β‐crystallin aggregates. Therefore, the βB2 subunit and, in particular its terminal extensions, has enhanced flexibility compared to the other β‐crystallin subunits. Furthermore, resonances arising from the C‐terminal extension of βB2‐crystallin are not present in the spectrum of the octomer, which is consistent with the C‐terminal extension binding in this aggregate and hence being involved in large aggregate formation. A possible interaction between the C‐terminal extension of βB2 and the hydrophobic βB1 subunit, which is only found in the octomer, is discussed. At higher temperatures (45°C) in the octomer, partial exposure of the C‐terminal extension of βB2 occurs indicating that the octomer may be starting to break up into smaller aggregates. Show more