1i5i
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(New page: 200px<br /><applet load="1i5i" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i5i, resolution 2.40Å" /> '''THE C18S MUTANT OF B...)
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Revision as of 14:57, 20 November 2007
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THE C18S MUTANT OF BOVINE (GAMMA-B)-CRYSTALLIN
Overview
The cysteine residues of the gamma crystallins, a family of ocular lens, proteins, are involved in the aggregation and phase separation of these, proteins. Both these phenomena are implicated in cataract formation. We, have used bovine gammaB crystallin as a model system to study the role of, the individual cysteine residues in the aggregation and phase separation, of the gamma crystallins. Here, we compare the thermodynamic and kinetic, behavior of the recombinant wild-type protein (WT) and the Cys18 to Ser, (C18S) mutant. We find that the solubilities of the two proteins are, similar. The kinetics of crystallization, however, are different. The WT, crystallizes slowly enough for the metastable liquid-liquid coexistence to, be easily observed. C18S, on the other hand, crystallizes rapidly; the, metastable coexisting liquid phases of the pure mutant do not form., Nevertheless, the coexistence curve of C18S can be determined provided, that crystallization is kinetically suppressed. In this way we found that, the coexistence curve coincides with that of the WT. Despite the, difference in the kinetics of crystallization, the two proteins were found, to have the same crystal forms and almost identical X-ray structures. Our, results demonstrate that even conservative point mutations can bring about, dramatic changes in the kinetics of crystallization. The implications of, our findings for cataract formation and protein crystallization are, discussed.
About this Structure
1I5I is a Single protein structure of sequence from Bos taurus. Full crystallographic information is available from OCA.
Reference
Enhanced crystallization of the Cys18 to Ser mutant of bovine gammaB crystallin., Asherie N, Pande J, Pande A, Zarutskie JA, Lomakin J, Lomakin A, Ogun O, Stern LJ, King J, Benedek GB, J Mol Biol. 2001 Dec 7;314(4):663-9. PMID:11733987
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