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Solubility of Thaumatin Neer Asherie,* Charles Ginsberg, Samuel Blass, Arieh Greenbaum, and Sarah Knafo

Summary: Solubility of Thaumatin
Neer Asherie,* Charles Ginsberg, Samuel Blass, Arieh Greenbaum, and Sarah Knafo
Department of Physics and Department of Biology, YeshiVa UniVersity, Belfer Hall 1412,
2495 Amsterdam AVenue, New York, New York 10033-3312
ReceiVed March 16, 2008; ReVised Manuscript ReceiVed April 8, 2008
ABSTRACT: Thaumatin, an intensely sweet protein, crystallizes rapidly in the presence of tartrate ions. The ease with which crystals
form has led to the use of thaumatin over the past decade as a model system for the study of protein crystallization. The available data on
the solubility of this protein, however, are inconsistent. We have purified thaumatin and determined its solubility with the L and D enantiomers
of the tartrate ion. We find that the crystal habit and solubility are significantly different for the two precipitants: the solubility increases
with temperature in L-tartrate, while it decreases with temperature in D-tartrate. Our results suggest that the chirality of precipitants is an
important factor that should be controlled when determining the solubility of proteins.
Proteins are crystallized by trial and error.1
Indeed, obtaining
high-quality crystals is still a challenge,2
and it is common to read
that "protein crystallization has always been a bit more of an art
than a science".3
As this state of affairs hampers the determination
of X-ray structures for proteins, much work continues to be carried
out to improve our understanding of protein phase behavior.4,5


Source: Asherie, Neer - Departments of Physics & Biology, Yeshiva University


Collections: Biology and Medicine; Physics