Cu4(CH3C(OH)(PO3)2)2(C4H4N2)(H2O)4: a novel, three-dimensional copper diphosphonate with metamagnetism

A novel, three-dimensional copper diphosphonate Cu4(CH3C(OH)(PO3)2)2(C4H4N2)(H2O)4 (1) incorporating an organic pyrazine ligand has been hydrothermally synthesized, which exhibits antiferromagnetic ordering below 4.2 K and metamagnetic behavior.

Zinc diphosphonates templated by organic amines: syntheses and characterizations of [NH3(CH2)2NH3]Zn(hedpH2)2*2H2O and [NH3(CH2)nNH3(CH2)nNH3]Zn2(hedpH)2*2H2O (n=4,5,6) (hedp=1-hydroxyethylidenediphophonate)

Four new zinc diphosphonate compounds with formulas [NH(3)(CH(2))(2)NH(3)]Zn(hedpH(2))(2).2H(2)O, 1, [NH(3)(CH(2))(n)()NH(3)]Zn(2)(hedpH)(2).2H(2)O, (n = 4, 2; n = 5, 3; n = 6, 4) (hedp = 1-hydroxyethylidenediphosphonate) have been synthesized under hydrothermal conditions at 110 degrees C and in the presence of alkylenediamines NH(2)(CH(2))(n)()NH(2) (n = 2, 4, 5, 6). Crystallographic data for 1: monoclinic, space group C2/c, a = 24.7422(15), b = 5.2889(2), c = 16.0338(2) A, beta = 117.903(1) degrees, V = 1856.17(18) A(3), Z = 4; 2: monoclinic, space group P2(1)/n, a = 5.4970(3), b = 12.1041(6), c = 16.2814(12) A, beta = 98.619(5) degrees, V = 1071.07(11) A(3), Z = 2; 3: monoclinic, space group P2(1)/n, a = 5.5251(2), b = 12.5968(3), c = 16.1705(5) A, beta = 99.182(1) degrees, V = 1111.02(6) A(3), Z = 2; 4: triclinic, space group P-1, a = 5.4785(2), b = 14.1940(5), c = 16.0682(6) A, alpha = 81.982(2) degrees, beta = 89.435(2) degrees, gamma = 79.679(2) degrees, V = 1217.11(8) A(3), Z = 2. In compound 1, two of the phosphonate oxygens are protonated. The metal ions are bridged by the hedpH(2)(2-) groups through three of the remaining four phosphonate oxygens, forming a one-dimensional infinite chain. The protonated ethylenediamines locate between the chains in the lattice. In compounds 2-4, only one phosphonate oxygen is protonated. Compounds 2 and 3 have a similar three-dimensional open-network structure composed of [Zn(2)(hedpH)(2)](n) double chains with strong hydrogen bonding interactions between them, thus generating channels along the [100] direction. The protonated diamines and water molecules reside in the channels. Compound 4 contains two types of [Zn(2)(hedpH)(2)](n) double chains which are held together by strong hydrogen bonds, forming a two-dimensional network. The interlayer spaces are occupied by the [NH(3)(CH(2))(6)NH(3)](2+) cations and water molecules. The significant difference between structures 2-4 is also featured by the coordination geometries of the zinc atoms. The geometries of those in 2 can be described as distorted octahedral, and those in 3 as distorted square pyramidal. In 4, two independent zinc atoms are found, each with a distorted octahedral and a tetrahedral geometry, respectively.

catena-Poly[[bis(thiocyanato-N)lead(II)]-μ-1,2-bis(4-pyridyl)ethane-N:N′]

In the title coordination polymer, [Pb(NCS)(2)(C(12)H(12)N(2))], the coordination geometry about the Pb(II) atom is a distorted octahedron, composed of two N atoms from bpe ligands [bpe is 1,2-bis(4-pyridyl)ethane], two other N atoms from NCS(-) groups and two neighbouring S atoms through short contacts. The trans-bpe ligands act as bridges between two Pb(II) centres resulting in the formation of a linear chain. The terminal S atoms of the NCS(-) ligands make short contacts with the Pb(II) atom of neighbouring chains to form an infinite two-dimensional polymeric structure.

Heterometallic polymeric clusters containing tetraselenotungstate anion: one-dimensional helical chain [[La(Me2SO)8

[PPh4]2[WSe4] reacts with an equivalent of [Ag(MeCN)4][ClO4] in DMF to afford a linear polymeric cluster [[Ph4P][(mu-WSe4)Ag]]n (1). Treatment of cluster 1 with excess La(NO3)3.3H2O in Me2SO solution resulted in the formation of a helical chain polymeric cluster [[La(Me2SO)8][(mu-WSe4)3Ag3]]n (2). Cluster 2 crystallizes in the monoclinic space group P2(1/n) with four formula units in a cell of dimensions a = 12.7642(5) A, b = 24.1725(9) A, c = 19.4012(7) A, and beta = 103.546(11) degrees. Refinement by full-matrix least-squares techniques gave final residuals R = 0.0540 and Rw = 0.1116 for 494 variables and 7593 reflections (Fo(2) > 2.0sigma(Fo(2))). The anion [[(mu-WSe4)3Ag3]]n(3n-) in 2 can be described as a butterfly-type SeWSe3Ag2 basic repeating unit linked through interactions with a Ag atom of one fragment and a Ag atom of another to form an intriguing helical array. The CuCN, KCN, and [Et4N]2[WSe4] reaction system resulted in the formation of a novel three-dimensional cluster [[Et4N]2[(mu4-WSe4)Cu4(CN)4]]n (4) either in DMF/2-picoline or in solid at 80 degrees C. Cluster 4 crystallizes in the orthorhombic space group Fddd with cell constants a = 11.090(2) A, b = 23.206(5) A, c = 23.910(5) A, and Z = 8. Anisotropic refinement with 1510 reflections (Fo(2) > 2.0sigma(Fo(2))) and 82 parameters for all non-hydrogen atoms yielded the values of R = 0.0428 and Rw = 0.0887. The anion structure of 4 is built up from a WSe4Cu4 unit bridged by cyanide ligands to form a three-dimensional cross framework. The air- and moisture-stable polymeric clusters easily decompose into small molecular clusters when treated with ligands such as PPh3 and pyridine (Py). Cluster 2 exhibits both strong optical absorption and an optical self-focusing effect (effective alpha2 = 2.2 x 10(-9) m2.W(-1), n2 = 6.8 x 10(-15) m2.W(-1); examined in a 0.13 mM DMF solution). Cluster 4 shows good photostability in the process of measurement and a large optical limiting effect (the limiting threshold is ca. 0.2 J.cm(-2)).

Evidence for a cysteine-histidine thioether bridge in functional units of molluscan haemocyanins and location of the disulfide bridges in functional units d and g of the betaC-haemocyanin of Helix pomatia

In functional units d and g from the betaC-haemocyanin of the gastropod Helix pomatia, aminoacid analysis in the presence of dimethyl sulfoxide showed the occurrence of seven cysteine residues. Titration with 5,5'-dithiobis(2-nitrobenzoic acid), however, did not reveal any free thiol group. Pepsinolysis at pH 2.0 followed by amino acid analysis and partial sequencing of the cysteine-containing peptides showed that six cysteine residues are involved in the formation of three disulfide bridges at corresponding positions. The results indicated that the remaining cysteine residue is linked by a thioether bridge to a histidine residue located two positions further in the sequence (H. pomatia d Cys60 His62; H. pomatia g Cys66 His68). This residue corresponds to one of the three histidine residues considered to be involved in the coordination of the copper A atom of the dinuclear copper group of the functional units. The presence of the thioether bond was further evidenced by an absorption band at 255 nm and by molecular mass determinations with electrospray mass spectrometry on a peptic peptide from H. pomatia d and on peptides obtained by proteolysis of carboxymethylated H. pomatia d with trypsin and pronase. Upon sequence analysis the cysteine-histidine thioether bridge was cleaved into didehydroalanine (polymers) and 2-thiolhistidine. A peptide with a cysteine-histidine thioether bridge was isolated from pepsinolysates of functional units c, e, f, g and h of Sepia officinalis and unit g of Octopus vulgaris, obtained from haemocyanin of the cephalopods S. officinalis and O. vulgaris. A cysteine-histidine thioether bridge, which was reported previously for tyrosinase of Neurospora crassa, thus seems to be a general feature for functional units of molluscan haemocyanins.

Pan/E2A expression precedes immunoglobulin heavy-chain expression during B lymphopoiesis in nontransformed cells, and Pan/E2A proteins are not detected in myeloid cells

A newly developed rat long-term bone marrow culture system was used to study the role of Pan/E2A basic helix-loop-helix transcription factors during B-cell development. In this system, B-lymphocyte progenitors actively differentiate into mature B cells. Monoclonal (Yae) and polyclonal (anti-Pan) antibodies were employed to characterize the expression of Pan proteins by Western blot assay during hematopoiesis and to examine the components of immunoglobulin heavy-chain gene enhancer element-binding species by electrophoretic mobility shift assay. During B-cell development, the appearance of Pan/E2A proteins preceded the expression of immunoglobulin heavy-chain protein. A Pan-containing immunoglobulin heavy-chain enhancer element (mu E5)-binding species (BCF1), composed of immunoreactive Pan-1/E47 but not Pan-2/E12, was observed concomitantly with the detection of Pan/E2A proteins. In addition to BCF1, other mu E5-binding species were detected which were not recognized by the Yae antibody. Two of these species were present in primary B-lymphocyte and myeloid cultures and were recognized by an anti-upstream stimulatory factor antiserum. Although Pan/E2A proteins have been proposed to be ubiquitous, Pan/E2A proteins were not detected in primary myeloid cultures composed mainly of granulocytes and macrophages or in the macrophage cell line J774. The absence of Pan/E2A proteins in differentiated myeloid cells correlated with low steady-state levels of Pan/E2A RNA. However, Pan/E2A proteins were present in a promyeloid cell line, 32DCL3, suggesting that extinction of Pan/E2A expression may play a role in myelopoiesis.

Purification of E. coli-synthesized Pan proteins and development of a Pan-specific monoclonal antibody

The helix-loop-helix (HLH) transcription factors, Pan-1 (E47) and Pan-2 (E12), are produced by the mechanism of alternative transcript splicing. Pan-1 and Pan-2 were expressed in Escherichia coli, and a purification scheme was developed. Purified Pan-2 was used to immunize Smith-Webster mice and a hybridoma was generated that produced a monoclonal antibody (Yae) that specifically recognized both native and denatured Pan-1 and Pan-2. Deletion mapping and sequence transfer studies have localized the determinant recognized by the Yae antibody to the region 195-208 of Pan-2. This region is conserved in Pan-1 and Pan-2. The Yae antibody recognized in vitro-synthesized ITF-1, a third E2A (Pan) gene product also produced by the mechanism of alternative RNA splicing, but did not recognize the related HLH proteins, ITF-2, REB alpha, or REB beta. By Western blot assay of pancreatic acinar cells, the Yae antibody detected a single protein species of 72 kD that comigrated with in vitro-synthesized Pan-1 and Pan-2.

Kinetics of E2A basic helix-loop-helix-protein expression during myelopoiesis and primary B cell differentiation

The DNA-binding factors encoded by the E2A gene, which include the basic helix-loop-helix proteins E12 and E47, are thought to regulate Ig gene expression. In the rat these factors are products of the Pan locus and are referred to as Pan-2 and Pan-1, respectively. To determine when during B cell differentiation Pan (E2A) DNA-binding proteins are first expressed, cells from a newly developed rat long term lymphoid bone marrow culture system were analyzed molecularly and phenotypically using a newly defined anti-Pan mAb. The data indicate that Pan-expressing cells appear in B cell progenitors before the appearance of the CD45R B lineage-associated Ag or microH chain protein. The results also indicate that Pan proteins are present in cells that had undergone D-JH rearrangements. Finally, although Pan (E2A) proteins are present in myeloid precursors, expression is extinguished as differentiation into mature myeloid cells occurs.

Kinetics of E2A basic helix-loop-helix-protein expression during myelopoiesis and primary B cell differentiation

The DNA-binding factors encoded by the E2A gene, which include the basic helix-loop-helix proteins E12 and E47, are thought to regulate Ig gene expression. In the rat these factors are products of the Pan locus and are referred to as Pan-2 and Pan-1, respectively. To determine when during B cell differentiation Pan (E2A) DNA-binding proteins are first expressed, cells from a newly developed rat long term lymphoid bone marrow culture system were analyzed molecularly and phenotypically using a newly defined anti-Pan mAb. The data indicate that Pan-expressing cells appear in B cell progenitors before the appearance of the CD45R B lineage-associated Ag or microH chain protein. The results also indicate that Pan proteins are present in cells that had undergone D-JH rearrangements. Finally, although Pan (E2A) proteins are present in myeloid precursors, expression is extinguished as differentiation into mature myeloid cells occurs.

The specificity and elastinolytic activities of bovine cathepsins S and H

Cathepsins S and H were purified from bovine spleen and their catalytic properties compared. The enzymes were shown to be similar by chromatographic properties and by the ability to hydrolyze Bz-Phe-Val-Arg-NHMec. They could however be distinguished by the fact that cathepsin S reacted with Z-[125I]Tyr-Ala-CHN2 and hydrolyzed Z-Phe-Arg-NHMec whereas cathepsin H did not. The substrate and inhibitor specificities of cathepsin H suggest that unlike cathepsins B, L, and S, it cannot accommodate peptides with aromatic side chains in P2. Cathepsins L and S can accommodate the aromatic side chain of tyrosine in P1 readily, whereas cathepsins H and B cannot. The specificities of each enzyme for synthetic substrates and inhibitors have enabled the construction of models of the architecture of the active sites of the mammalian cysteine proteinases which clearly show the differences between the four enzymes. A significant characteristic of cathepsin S is that it can hydrolyze insoluble elastin at both acidic and neutral pH; this distinguishes it from all of the other lysosomal proteinases.