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.
IBM T. J. Watson Research Center, Yorktown Heights, New York 10598.
S H
SH
Koenig
R D
RD
Brown
A K
AK
Kenworthy
A D
AD
Magid
R
R
Ugolini
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