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PDBsum entry 1thw
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Sweet tasting protein
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PDB id
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1thw
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References listed in PDB file
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Key reference
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Title
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Structures of three crystal forms of the sweet protein thaumatin.
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Authors
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T.P.Ko,
J.Day,
A.Greenwood,
A.Mcpherson.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 1994,
50,
813-825.
[DOI no: ]
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
percentage match of
94%.
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Abstract
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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 A, and beta = 94.0 degrees,
P2(1)2(1)2(1) with a = 44.3, b = 63.7 and c = 72.7 A, and a tetragonal form
P4(1)2(1)2 with a = b = 58.6 and c = 151.8 A. 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 A, 0.165 for the orthorhombic at 1.75
A, and 0.181 for the tetragonal, also at 1.75 A 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 A for Calpha atoms, and 1.1 to 1.3 A 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.
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Figure 5.
Fig. 5.2Fo - Fc electron-density map for the bound tartrate in the -is0 --90
tetragonal crystal. The map was calculated as in Fig. 4. For
clarity only a box of density sufficient to encompass the tartrate
molecule is shown.. Similar density was also observed in the
Fo-Fc
map based on the original model. Also shown are
nearby protein atoms. Seen labeled are the interacting groups
from Lys137, Tyr157, Arg29 i, Ser36' and Lys67".
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Figure 10.
Fig. 10. Superposition of all-atom models after refinement in the
C2,
P2~2~2t and P4~2~2 crystals, colored green, blue and red,
respectively, on the original model, colored purple.
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The above figures are
reprinted
by permission from the IUCr:
Acta Crystallogr D Biol Crystallogr
(1994,
50,
813-825)
copyright 1994.
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