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Title
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Cocrystals of yeast cytochrome c peroxidase and horse heart cytochrome c.
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Authors
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T.L.Poulos,
S.Sheriff,
A.J.Howard.
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Ref.
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J Biol Chem, 1987,
262,
13881-13884.
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PubMed id
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Abstract
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Yeast cytochrome c peroxidase and horse heart cytochrome c have been
cocrystallized in a form suitable for x-ray diffraction studies and the
structure determined at 3.3 A. The asymmetric unit contains a dimer of the
peroxidase which was oriented and positioned in the unit cell using molecular
replacement techniques. Similar attempts to locate the cytochrome c molecules
were unsuccessful. The peroxidase dimer model was subjected to eight rounds of
restrained parameters least squares refinement after which the crystallographic
R factor was 0.27 at 3.3 A. Examination of a 2Fo-Fc electron density map showed
large "empty" regions between peroxidase dimers with no indication of cytochrome
c molecules. Electrophoretic analysis of the crystals demonstrated the presence
of the peroxidase and cytochrome c in an approximate equal molar ratio.
Therefore, while cytochrome c molecules are present in the unit cell they are
orientationally disordered and occupy the space between peroxidase dimers.
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