John M. A. Smith

Bacterioferritins and ferritins are distantly related in evolution : conservation of ferroxidase-centre residues

Iron‐storage proteins can be divided into two classes; the bacterioferritins and ferritins. In spite of many apparent structural and functional analogies, no significant amino acid sequence similarity has been detected previously. This report now reveals a distant evolutionary relationship between bacterioferritins and ferritins derived by ‘Profile Analysis’. Optimum alignment of bacterioferritin and ferritin sequences suggests that key residues of the ferroxidase centres of ferritins are conserved in bacterioferritins.

Physical, chemical and immunological properties of the bacterioferritins of Escherichia coli, Pseudomonas aeruginosa and Azotobacter vinelandii.

The 70-amino-acid-residue N-terminal sequence of the bacterioferritin (BFR) of Azotobacter vinelandii was determined and shown to be highly similar to the N-terminal sequences of the Escherichia coli and Nitrobacter winogradskyi bacterioferritins. Electrophoretic and immunological analyses further indicate that the bacterioferritins of E. coli, A. vinelandii and Pseudomonas aeruginosa are closely related. A novel, two-subunit assembly state that predominates over the 24-subunit form of BFR at low pH was demonstrated. The results indicate that the bacterioferritins form a family of proteins that are distinct from the ferritins of plants and animals.

Molecular size and symmetry of the bacterioferritin of Escherichia coli: X-ray crystallographic characterization of four crystal forms

X-ray crystallographic data from four crystal forms of Escherichia coli bacterioferritin show that the molecule has a diameter in the range 119 to 128 A. Molecules are composed of 24 subunits arranged in 432 symmetry. In both size and symmetry the molecule resembles ferritin from eukaryotes. The four crystal forms are monoclinic, space group P2(1) with unit cell dimensions a = 118.7 A, b = 211.6 A, c = 123.3 A and beta = 119.1 degrees; orthorhombic, C222(1), a = 128.7 A, b = 197.1 A, c = 202.8 A; tetragonal, P4(2)2(1)2, a = b = 210.6 A, c = 145.0 A and cubic, I432, a = 146.9 A.

Aspects of the inorganic chemistry of rubber vulcanisation. Part 2. Anionic mixed-ligand zinc complexes derived from dialkyldithiocarbamates, 2-mercapto-benzothiazole, -benzoxazole, and -benzimidazole, and the crystal and molecular structures of [NEt4][Zn(S2CNMe2)3], [NBun4][Zn(C7H4NS2)3(OH2)], [NBun4][Zn(S2CNMe2)2(C7H4NS2)]˙C2H5OH, and [NBun4][Zn(S2CNMe2)(C7H4NS2)2]

The complexes [Zn(S2CNR2)3]–(R = Me or Et), [Zn(S2CNR2)(S2CNR′2)2]–[R = Me, Et, or Bun; R′= Me or Et; R2=(CH2)5, R′= Me or Et], [Zn(C7H4NS2)3(OH2)]–(C7H4NS2= benzothiazole-2-thiolate), [Zn(S2CNR2)2(C7H4NS2)]–[R = Me, Et, or Bun; R2=(CH2)5], [Zn(S2CNR2)2(C7H4NOS)]–[R = Me, Et, or Bun; R2=(CH2)5; C7H4NOS = benzoxazole-2-thiolate], [Zn(S2CNR2)(C7H4NS2)2]–[R = Me, Et, Bun, or C6H11; R2=(CH2)5], [Zn(S2CNR2)(C7H4NOS)2]–[R = Me or Et; R2=(CH2)5], and [Zn{S2[graphic omitted]H2}(C7H5N2S)2]–(C7H5N2S = benzimidazole-2-thiolate) have been isolated as their [NMe4]+ and [NBun4]+salts. The compounds [NR″4][S2CNR2][R″= Me or Bun; R = Et or C6H11; R2=(CH2)5], [NR″4][C7H4NS2], [NR″4][C7H4NOS](R″= Me or Bun), [NBun4][C7H5N2S], and [NBun4][C3H4NS2](C3H4NS2= thiazoline-2-thiolate) have also been prepared. The structures of the four title complexes have been determined crystallographically. The nature of the distortions from regular co-ordination geometries is some of these species are discussed and related to the molecular structures of [{Zn(S2CNR2)2}2](R = Me or Et).

Crystal and molecular structure of a seven-coordinate chloroindium(III) complex of 1,4,7-triazacyclononanetriacetic acid

Abstract The title macrocyclic ligand forms a seven-coordinate chloroindium complex which exists as a stable neutral hexacoordinate species in aqueous solution.

The location of exon boundaries in the multimeric iron-storage protein ferritin

SummaryThe nature of the amino acids whose codons border introns in ferritin genes is novel; the disposition of these intron boundaries within the three-dimensional structure of the 24-subunit molecule differs significantly from that of other proteins. These observations are discussed in relation to the functions of isoferritins.

Nitrosyl complexes of molybdenum and tungsten. Part 17. Hydrazido(1–) complexes of [tris(3,5-dimethylpyrazolyl)borato]molybdenum, related tungsten compounds, and the structures of NN-dimethylhydrazido(1–)- and N-methyl-N-phenylhydrazido(1–)iodo(nitrosyl)[tris(3,5-dimethylpyrazol-1-yl)borato]molybdenum

The preparations of the compounds [Mo{HB(Me2pz)3}(NO)I(NHNRR′)](Me2pz = 3,5-dimethylpyrazolyl; R = R′= H or Me; R = H, R′= Me or Ph; R = Me, R′= Ph) and [W{HB(Me2pz)2(3,5-Me2-4-BrC3N2)}(NO)Br(NHNRR′)](R = R′= H or Me; R = H, R′= Ph) are described. The species with R = R′= H react with acetone giving complexes containing the -NHNCMe2 group, and the hydrazido(1–) species react with acids causing cleavage of the M–NHNRR′ bond. The structures of [Mo{HB(Me2pz)3}(NO)I(NHNRR′)](R = R′= Me; R = Me, R′= Ph) have been determined crystallographically.

Nitrosyl complexes of molybdenum and tungsten. Part 16. Symmetrical and unsymmetrical bis-alkoxo- and mixed alkoxo-amido-complexes of tris(3,5-dimethylpyrazolyl) boratomolybdenum, related tungsten species, and the structure of bis(ethoxo)-, bis(isopropoxo)-, and ethoxo(isopropoxo)-nitrosyl[tris(3,5-dimethylpyrazolyl)borato]-molybdenum

The complex [Mo{HB(Me2pz)3}(NO)X(Y)][Me2pz = 3,5-dimethylpyrazolyl; X = I, Y = OH, OC6H11, and OCH2C2CH2OH; X = Y = OR (R = H, Me, Et, Pri, and Bui); X = OEt, Y = OPri; X = OPri, Y = OBui; X = OR, Y = NHR′(R = Me, R′= H, Me, and Et; R = Et, R′= H, Me, Et, Prn, C6H11, and CH2Ph; R = Pri, R′= H, Me, Et, Pri, and C6H11)] and [W{HB(Me2pz)2(3,5-Me2-4-BrC3N2)}(NO)X(Y)](X = Br, Y = OMe, OEt, and OPri; X = Y = OEt) have been prepared and characterised spectroscopically. The complexes [Mo{HB(Me2pz)3}(NO)(OR)(NH2)](R = Me, Et, or Pri) react with acetone affording [Mo{HB(Me2pz)3}-(NO)(NCMe2)(OR)]·n(CH3)2CO. The structures of [Mo{HB(Me2pz)3}(NO)(OR)(OR′)](R = R′= Et or Pri; R = Et, R′= Pri) have been determined crystallographically. For R = Et, R′= Pri, crystals are monoclinic, with a= 14.46(4), b= 21.67(6), c= 8.015(14)A, β= 96.08(3)°, space group P21/n, and R 0.0388; for R = R′= Pri, crystals are triclinic, with a= 11.758(8), b= 14.403(9), c= 8.173(14)A, α= 97.970(16), β= 77.30(3), γ= 96.523(7)°, space group P, and R 0.0398; for R = R′= Et, crystals are monoclinic, with a= 14.73 b= 21.09, c= 8.00 A, β= 94.80° and space group P21/n. The molecules are six-co-ordinate, with linear Mo–N–O groups and short Mo–O bond lengths (1.90 A).

Nitrosyl complexes of molybdenum and tungsten. Part 15. Iodo(monoalkylamido)nitrosyl[tris(3,5-dimethylpyrazolyl)borato]molybdenum complexes, some related tungsten compounds, and the crystal and molecular structure of ethylamido(iodo)nitrosyl[tris(3,5-dimethyl-pyrazolyl) borato]molybdenum

The complexes [Mo{HB(3,5-Me2C3HN2)3}(NO)I(Y)](Y = NMe2 or NHR, where R = H, Me, Et, Prn, Pri, Bun, Bui, C6H11, C3H5, or CH2Ph) and [W{HB(3,5-Me2C3HN2)2(4-Br-3,5-Me2C3N2)})(NO)Br(Y)](Y = H, Pri, or CH2Ph) have been prepared by treatment of the species where Y = I (MO) or Br (W) with ammonia, primary amines, and NHMe2 respectively. Reaction of [Mo{HB(3,5-Me2C3HN2)3}(NO)I(NH2)] with HCl, and with acetone in the presence of NEt3 respectively, gives [Mo{HB(3,5-Me2C3HN2)3}(NO)Cl2] and [NH4]Cl, and [Mo{HB(3,5-Me2C3HN2)3}(NO)I(NCMe2)]·Me2CO. The crystal and molecular structure of [Mo{HB(3,5-Me2C3HN2)3}(NO)I(NHEt)], as a di-isopropyl ether solvate, has been determined by X-ray diffraction methods using counter data and refined by block-diagonal least-squares procedures, to R= 0.0534 for 3 150 reflections. The molecule is six-co-ordinate, with a linear Mo–N–O group, and a short Mo–NHEt bond. Crystals are monoclinic with a= 40.00(3), b= 12.751 (10), c= 10.60(3)A, β= 97.23(2)°, space group P21/a, and Z= 8.

Structural homology between mouse liver and horse spleen ferritins

Mouse liver ferritin is composed almost exclusively of polypeptide chains similar in molecular mass (22 kDa) to that characteristic of the major chain (H) found in heart ferritin isolated from human, horse or rat. In these species the predominant polypeptide of liver (L) is smaller (about 20 kDa). Here we show that mouse liver and horse spleen ferritins and apoferritins exhibit extensive structural homology as judged by the similarity in the diffraction patterns of their crystals grown from cadmium sulphate solutions. Implications of this finding are discussed.