Jan-Olof Lundgren

Homology relationships among the small blue proteins

COMPARATIVELY few blue proteins, all containing copper, are found in nature. Isolated from organisms all along the evolutionary scale they are1 the ‘blue oxidases’—laccase and ascorbate oxidase of plant origin and ceruloplasmin (ferroxidase) from mammalian serum (molecular weights 60,000–140,000, 4–8 Cu mol−1)—and the ‘small blue proteins’—azurins from bacteria, plastocyanins from photosynthetic cells and others like stellacyanin and umecyanin, found in higher plants (molecular weights, carbohydrate excluded, 11,000–14,000, 1 Cu mol−1). The small blue proteins may all function as electron carriers although a precise role is known only for the plastocyanins.

Hydrogen‐Bond Studies. XXX. The Crystal Structure of Hydrogen Bromide Tetrahydrate, (H7O3)+(H9O4)+2Br−·H2O

The crystal structure of hydrogen bromide tetrahydrate (HBr·4H2O) has been determined from three‐dimensional single‐crystal x‐ray data recorded at −180°C. Crystals of this compound are monoclinic, space group P21, with four formula units in a cell with the dimensions: a = 7.043, b = 11.466, c = 7.339 A, β = 110.85°. The structure determination shows that the compound may be formulated as (H7O3)+(H9O4)+2Br−·H2O. The hydrogen‐bond lengths within H7O3+ are 2.465 and 2.498 A, and within H9O4+2.496, 2.587, and 2.588 A. Other O–H···O bonds in the structure are about 2.75 A.

On the evolution of blue proteins

Amino acid sequences of 8 plastocyanins, 8 azurins, stellacyanin, two regions in human ceruloplasmin (ferroxidase)--all of which proteins are known to bind a blue (type 1) copper--and subunit II of bovine mitochondrial cytochrome c oxidase were compared by statistical methods to assess similarities and derive possible evolutionary relationships. It is suggested that all of the examined proteins are monophyletic. The two ceruloplasmin partial sequences clearly demonstrate that this protein has undergone a duplication. A calculated most parcimonious phylogenetic tree shows the divergence of the azurin and plastocyanin ancestor to be the earliest event. Stellacyanin and later the blue oxidase (ceruloplasmin) evolved from the plastocyanin branch, which the cytochrome c oxidase subunit evolved from the azurin ancestor.

Charge density in pyroelectric lithium sulfate monohydrate at 80 and 298 K

Lithium sulfate monohydrate has been studied at 80 and 298 K by x‐ray diffraction. The monoclinic crystal with space group P21 has lattice dimensions at 298 K of a=5.4553(1), b=4.8690(1), c=8.1761(2) A, and β=107.337(2)°; lattice dimensions at 80 K were reported in our neutron study [J. Chem. Phys. 80, 423 (1984)]. Least‐squares refinement based on 3486 (80 K) and 3390 (298 K) independent reflections, assuming a spherical atom model, results in final R( F 2) values of 0.024 (80 K) and 0.026 (298 K). Static deformation and charge density model refinement, based on Hirshfeld‐type multipole functions, greatly reduces the residual electron density and gives R( F 2) values of 0.017 (80 K) and 0.016 (298 K). Refinement of the resulting multipole parameters within the Gaussian radial dependence model allows a qualitative estimation of the differences in electron densities between 80 and 298 K. A change of about 0.2 e A−3 in the deformation density of the O–H bonds in the water molecule over this temperature rang...

Neutron diffraction study of oxonium trifluoromethanesulphonate

HaO+CF3SO3, monoclinic, P2 l/c, Z = 4, a = 5.9634(3), b = 9.975 (3), c = 9.708 (1) A, fl = 98.661 (7) ° (Spencer & Lundgren (1973). Acta Cryst. B29, 1923-1928). Neutron wavelength 1.210 A, g(measured) = 0.57 cm -~, m.p. 34°C. Intensity data were recorded at 21 °C. Refinement with 801 observed data gave R(F 2) = 0.090, Rw(F 2) = 0.078. The oxonium ion, which is in an asymmetric environment, displays a moderate distortion from C3v symmetry. The O--H distances are 0.986, 0.997 and 0.998 (5) A; the H-O--H angles are 110.9, 111.7 and 116.0 (4) °. The H30 + ion is hydrogen bonded to three different CF3SO 3 ions by bonds of length 2.522 (3), 2.579 (4) and 2.673 (3) A. Introduction. The present investigation was under- taken to study the geometry of the oxonium ion, H30 +, in an environment known from an earlier X-ray study (Spencer & Lundgren, 1973) to be asymmetric. A neutron diffraction study of oxonium p-toluene- sulphonate was reported by Lundgren & Williams (1973), where the environment of the H3 O+ ion has a virtual threefold symmetry, i.e. the H3 O+.--O bonds are all the same length, 2.52-2.54 A, and the O...H30 +... O angles are very similar, 103.8-114.9 ° Neutron diffraction studies of structures where the oxonium ion is hydrogen bonded to water molecules to form HsO + or HTO + complexes have been reported for picrylsulphonic acid tetrahydrate (Lundgren & Tellgren, 1974), and hydrogen bromide dihydrate and o-sulphobenzoic acid trihydrate (Attig & Williams,

Phase Transitions in CsH3(SeO3)2 and CsD3(SeO3)2

Three phase transitions have been observed in CsD3(SeO3)2 using differential scanning calorimetry combined with measurements of the temperature dependence of the dielectric constant, lattice constants, and superlattice-reflection intensities. It is shown that a transition at -65°C reported for the first time corresponds to the antiferroelectric -128°C transition in CsH3(SeO3)2. Two additional transitions in the deuterated compound were observed in the room-temperature range, both accompanied by pronounced thermal hysteresis. One of these phases may appear in a monoclinic modification, in contrast to the triclinic antiferroelectric and paraelectric phases.