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Title
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Preliminary crystallographic data on monomeric and dimeric hemoglobins from the sea cucumber, Molpadia arenicola.
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Authors
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W.M.Carson,
T.R.Bowers,
G.B.Kitto,
M.L.Hackert.
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Ref.
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J Biol Chem, 1979,
254,
7400-7402.
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PubMed id
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Abstract
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Large single crystals of two distinct globin chains from coelomic cells of the
sea cucumber Molpadia arenicola have been prepared and examined by x-ray
crystallography. These hemoglobins exhibit a variety of ligand-dependent
association states with the met-hemoglobins existing as monomers and liganded
hemoglobins as dimers at physiological concentrations. Monomeric methemoglobin C
chain crystallizes in space group P21, with a = 46.0 A, b = 45.3 A, c = 40.9 A,
beta = 104.5 degrees, and one monomer per asymmetric unit. These crystals
exhibit unusual spectroscopic behavior when examined with a polarizer, turning
colorless in certain orientations. This implies that all the heme rings are
nearly parallel within the crystals. Dimeric cyanmethemoglobin D chain
crystallizes in space group P41212 (P43212), with a = b = 77.0 A, c = 61.5 A,
and one-half a dimer per asymmetric unit. These homodimers thus possess a
molecular 2-fold which is aligned with the crystallographic dyad.
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