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PDBsum entry 2azt
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References listed in PDB file
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Key reference
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Title
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Destabilization of human glycine n-Methyltransferase by h176n mutation.
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Authors
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Z.Luka,
S.Pakhomova,
Y.Luka,
M.E.Newcomer,
C.Wagner.
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Ref.
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Protein Sci, 2007,
16,
1957-1964.
[DOI no: ]
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PubMed id
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Abstract
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In the presence of moderate (2-4 M) urea concentrations the tetrameric enzyme,
glycine N-methyltransferase (GNMT), dissociates into compact monomers. Higher
concentrations of urea (7-8 M) promote complete denaturation of the enzyme. We
report here that the H176N mutation in this enzyme, found in humans with
hypermethioninaemia, significantly decreases stability of the tetramer, although
H176 is located far from the intersubunit contact areas. Dissociation of the
tetramer to compact monomers and unfolding of compact monomers of the mutant
protein were detected by circular dichroism, quenching of fluorescence emission,
size-exclusion chromatography, and enzyme activity. The values of apparent free
energy of dissociation of tetramer and of unfolding of compact monomers for the
H176N mutant (27.7 and 4.2 kcal/mol, respectively) are lower than those of
wild-type protein (37.5 and 6.2 kcal/mol). A 2.7 A resolution structure of the
mutant protein revealed no significant difference in the conformation of the
protein near the mutated residue.
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Figure 5.
Figure 5. Study of unfolding of wild-type and H176N mutant GNMTs by
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Figure 7.
Figure 7. Histidine and asparagine 176 interactions with neighboring
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The above figures are
reprinted
by permission from the Protein Society:
Protein Sci
(2007,
16,
1957-1964)
copyright 2007.
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