ISSN:
1399-0047
Source:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Three crystal forms of the sweet-tasting protein thaumatin from the African berry Thaumatococcus daniellii have been grown. These include two naturally occurring isoforms, A and B, that differ by a single amino acid, and a recombinant form of isoform B expressed in yeast. The crystals are of space groups C2 with a = 117.7, b = 44.9, c = 38.0 Å, and β = 94.0°, P212121 with a = 44.3, b = 63.7 and c = 72.7 Å, and a tetragonal form P41212 with a = b = 58.6 and c = 151.8 Å. The structures of all three crystals have been solved by molecular replacement and subsequently refined to R factors of 0.184 for the monoclinic at 2.6 Å, 0.165 for the orthorhombic at 1.75 Å, and 0.181 for the tetragonal, also at 1.75 Å resolution. No solvent was included in the monoclinic crystal while 123 and 105 water molecules were included in the higher resolution orthorhombic and tetragonal structures, respectively. A bound tartrate molecule was also clearly visible in the tetragonal structure. The r.m.s. deviations between molecular structures in the three crystals range from 0.6 to 0.7 Å for Cα atoms, and 1.1 to 1.3 Å for all atoms. This is comparable to the r.m.s. deviation between the three structures and the starting model. Nevertheless, several peptide loops show particularly large variations from the initial model.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1107/S0907444994005512
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