Summary: Observation of liquid­liquid phase separation for eye
lens S-crystallin
Onofrio Annunziata, Olutayo Ogun, and George B. Benedek*
Department of Physics, Center for Materials Science and Engineering, and Materials Processing Center, Massachusetts Institute of Technology,
Cambridge, MA 02139-4307
Contributed by George B. Benedek, December 6, 2002
S-crystallin ( S) is an important human and bovine eye lens
protein involved in maintaining the transparency of the eye. By
adding small amounts of polyethylene glycol (PEG) to the binary
aqueous bovine S solutions, we have observed liquid­liquid
phase separation (LLPS) at 8°C and revealed that, in the binary
S­water system, this phase transition would occur at 28°C. We
have measured both the effect of PEG concentration on the LLPS
temperature and protein PEG partitioning between the two liquid
coexisting phases. We use our measurements of protein PEG
partitioning to determine the nature and the magnitude of the
S-PEG interactions and to quantitatively assess the effectiveness
of PEG as a crystallizing agent for S. We use our measurements of
LLPS temperature as a function of protein and PEG concentration
to successfully determine the location of the critical point for the

Source: Annunziata, Onofrio - Department of Chemistry, Texas Christian University
Benedek, George B. - Department of Physics, Massachusetts Institute of Technology (MIT)

Collections: Chemistry; Physics