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Title
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X-ray crystal structure of ferric Aplysia limacina myoglobin in different liganded states.
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Authors
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E.Conti,
C.Moser,
M.Rizzi,
A.Mattevi,
C.Lionetti,
A.Coda,
P.Ascenzi,
M.Brunori,
M.Bolognesi.
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Ref.
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J Mol Biol, 1993,
233,
498-508.
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PubMed id
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Abstract
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The X-ray crystal structure of the ligand-free ferric form of Aplysia limacina
myoglobin (pH 6.0) has been refined at 1.7 A resolution (R = 15.1%), and its
cyanide, thiocyanate and imidazole derivatives studied by difference Fourier
techniques at atomic resolution. The crystallographic R-factors of the three
different derivatives reported are 16.1%, 16.1% and 15.6% at 1.8 A, 2.0 A and
2.0 A resolution, respectively. The present results have been analyzed in
parallel with previous crystallographic studies on the molecular structures of
the fluoride and azide derivatives of ferric Aplysia limacina myoglobin. Ligand
binding to the distal site of the heme pocket results in different networks of
hydrogen bonds involving to various degrees the bound ligand, residue
Arg(66)E10, the heme propionate III, ordered water molecules and/or protein
backbone atoms from the CD region. In particular, Arg(66)E10 stabilizes the
bound ligand and compensates for the absence of the hydrogen bond donor residue
HisE7, commonly present in oxygen-carrying globins.
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