Intermolecular protein interactions in solutions of bovine lens beta L-crystallin. Results from 1/T1 nuclear magnetic relaxation dispersion profiles.
We report the magnetic field dependence of 1/T1 of solvent water protons and deuterons (nuclear magnetic relaxation dispersion, or NMRD, profiles) for solutions of steer lens beta L-crystallin. Such data allow the study of intermolecular protein interactions over a wide concentration range, here 1-34% vol/vol, by providing a measure of the rotational relaxation time of solute macromolecules. We conclude that, for approximately less than 5% protein, the solute particles are noncompact, with a rotationally averaged volume approximately three times that of a compact 60-kD sphere. (Earlier results for alpha-crystallin, approximately 1,000 kD, from optical and osmotic measurements (Vérétout and Tardieu, 1989. J. Mol. Biol. 205:713-728), show a similar, approximately twofold, effect). At intermediate concentrations, to approximately 20% protein, there is evidence for limited association or oligomerization, as found for the structurally related gamma II-crystallin (Koenig et al. 1990. Biophys. J. 57:461-469), to a limiting size about two-thirds that of alpha-crystallin. The difference in NMRD behavior of the three classes of crystallins is consonant with their differing osmotic properties (Vérétout and Tardieu. J. Mol. Biol. 1989, 205:713-728; Kenworthy, McIntosh, and Magid. Biophys. J. 1992. 61:A477; Tardieu et al. 1992. Eur. Biophys. J. 21:1-12). We indicate how the unusual structures and interactions of these three classes of proteins can be combined to optimize transparency and minimize colloid osmotic difficulties in eye lens.
Koenig
S H
SH
IBM T. J. Watson Research Center, Yorktown Heights, New York 10598.
Brown
R D
RD
Kenworthy
A K
AK
Magid
A D
AD
Ugolini
R
R
D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002417:Cattle; D003102:Colloids / Q000737:chemistry; D003459:Crystallins / Q000737:chemistry*; D003903:Deuterium; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D015394:Molecular Structure; D008970:Molecular Weight; D009995:Osmosis; D011522:Protons; D012996:Solutions; D013696:Temperature
D003102:Colloids; D003459:Crystallins; D046911:Macromolecular Substances; D011522:Protons; D012996:Solutions; D003903:Deuterium