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The crystal structure of the oxygenated form of subunit II of Limulus polyphemus hemocyanin.
COPPER
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THE CRYSTAL STRUCTURE OFTHE OXYGENATED FORM OF SUBUNIT II OF LIMULUS POL YPHEMUS HEMOCYANIN.
K.A.Maanus and H. Ton-That Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44 106 U.S.A. Hemocyanins are copper-containing proteins that transport oxygen in a variety of invertebrates. The hemocyanin of the horseshoe crab, Limulus polyphemus, has a molecular weight of about 3x106 daltons and binds oxygen cooperatively. The whole molecule is composed of 48 subunits of eight different types, each with molecular weight approximately 73,000 daltons. All subunits are capable of binding one molecule of oxygen (and other ligands) at an active site comprising two coppers ligated by histidine residues. Large blue crystals suitable for atomic resolution x-ray diffraction studies have been grown of the oxygenated form of subunit II of Limulus hemocyanin [I]. They have the symmetry of the space group R32 with lattice constants a = b = 117.2 k 0.6 A, c = 286.9 f, 0.9 A. These crystals contain one subunit II polypeptide of molecular weight 72,950 per asymmetric unit and diffract to at least 2.4 A resolution. Initial phase information for the oxygenated Limulus II structure at 4 A resolution [2] was obtained by molecular replacement using the known structure of the deoxygenated form of Panulirus interruptus hemocyanin as the test molecule [3]. We have extended our data to 3 A resolution and currently have a refined model of the oxygenated Limulus II structure with an R factor of 25%. 1. 2. 3.
K.A. Magnus and W.E. Love J. Mol. Biol. 116, 171 (1975). K.A. Magnus, E.E. Lattman, A. Volbeda and W.G.J. HOI Proteins in press (1991). A. Volbeda and W.G.J. HOI J. MO/ Biol. 209, 249 (1989).
This work is supported
by an NSF grant DMB 90-04561.
COO6
167
THE CRYSTAL STRUCTURE OFTHE OXYGENATED FORM OF SUBUNIT II OF LIMULUS POL YPHEMUS HEMOCYANIN.
K.A.Maanus and H. Ton-That Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44 106 U.S.A. Hemocyanins are copper-containing proteins that transport oxygen in a variety of invertebrates. The hemocyanin of the horseshoe crab, Limulus polyphemus, has a molecular weight of about 3x106 daltons and binds oxygen cooperatively. The whole molecule is composed of 48 subunits of eight different types, each with molecular weight approximately 73,000 daltons. All subunits are capable of binding one molecule of oxygen (and other ligands) at an active site comprising two coppers ligated by histidine residues. Large blue crystals suitable for atomic resolution x-ray diffraction studies have been grown of the oxygenated form of subunit II of Limulus hemocyanin [I]. They have the symmetry of the space group R32 with lattice constants a = b = 117.2 k 0.6 A, c = 286.9 f, 0.9 A. These crystals contain one subunit II polypeptide of molecular weight 72,950 per asymmetric unit and diffract to at least 2.4 A resolution. Initial phase information for the oxygenated Limulus II structure at 4 A resolution [2] was obtained by molecular replacement using the known structure of the deoxygenated form of Panulirus interruptus hemocyanin as the test molecule [3]. We have extended our data to 3 A resolution and currently have a refined model of the oxygenated Limulus II structure with an R factor of 25%. 1. 2. 3.
K.A. Magnus and W.E. Love J. Mol. Biol. 116, 171 (1975). K.A. Magnus, E.E. Lattman, A. Volbeda and W.G.J. HOI Proteins in press (1991). A. Volbeda and W.G.J. HOI J. MO/ Biol. 209, 249 (1989).
This work is supported
by an NSF grant DMB 90-04561.