J Biol Chem 1979 Aug 10;25415:7400-2.

Preliminary crystallographic data on monomeric and dimeric hemoglobins from the sea cucumber, Molpadia arenicola.

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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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Genes referenced: LOC100887844 LOC115925415 LOC592256