The development of geotextiles incorporating slow-release phosphate beads for the maintenance of oil degrading bacteria in permeable pavements.

The development of a self-fertilising geotextile mat designed to provide a sustained slow-release of required inorganic nutrients for the growth of oil degrading microorganisms in porous pavement systems (PPS) is reported. The system comprises a geotextile spun from polymer fibres containing spherical phosphated polymer beads that release phosphate upon contact with water at a desirable level for microbial growth. Initial results using model PPS have shown that the self-fertilising geotextile system works extremely effectively as increased microbial activity has been observed throughout the experiment, illustrating that the oil-degrading bacteria can effectively utilise this polymer composite as a suitable nutrient source.

Conformations of three heterocyclic perhydropyrrolobenzofurans and polymeric assembly via co-operative intermolecular C-H...O hydrogen bonds.

In 1-cyclohexyl-6,6,8a-trimethyl-3a,6,7,8a-tetrahydro-1H-1-benzofuro[2,3-b]pyrrole-2,4(3H,5H)-dione, C19H27NO3, (I), and the isomorphous compounds 6,6,8a-trimethyl-1-phenyl-3a,6,7,8a-tetrahydro-1H-1-benzofuro[2,3-b]pyrrole-2,4(3H,5H)-dione, C19H21NO3, (II), and 6,6,8a-trimethyl-1-(3-pyridyl)-3a,6,7,8a-tetrahydro-1H-1-benzofuro[2,3-b]pyrrole-2,4(3H,5H)-dione, C18H20N2O3, (III), the tetrahydrobenzo-dihydrofuro-pyrrolidine ring systems are folded at the cis junction of the five-membered rings, giving rise to a non-planar shape of the tricyclic cores. The dihydrofuran and pyrrolidine rings in (I) are puckered and adopt an envelope conformation. The cyclohexene rings adopt a half-chair conformation in all the molecules, while the substituent N-cyclohexyl ring in (I) assumes a chair form. Short intramolecular C-H...O contacts form S(5) and S(6) motifs. The isomorphous compounds (II) and (III) are effectively isostructural, and aggregate into chains via intermolecular C-H...O hydrogen bonds.

2-Amino-5-methyl-1,3,4-thiadiazole and 2-amino-5-ethyl-1,3,4-thiadiazole.

The structures of 2-amino-5-methyl-1,3,4-thiadiazole, C(3)H(5)N(3)S, and 2-amino-5-ethyl-1,3,4-thiadiazole, C(4)H(7)N(3)S, have been determined for comparison with unsubstituted 2-amino-1,3,4-thiadiazole. Despite their different space groups (P2(1)/n and Pbca, respectively), the packing modes of the methyl and ethyl derivatives are similar, with comparable three-dimensional hydrogen-bonding associations. This is in contrast to the hydrogen-bonding network in 2-amino-1,3,4-thiadiazole, which is one-dimensional and has denser packing. It is shown that both packing forms are different polymorphs of a specific subunit of each array.

trans-Bis(2-amino-6-nitro-1,3-benzothiazole-N)dichloroplatinum(II) tetrakis(N,N'-dimethylformamide) solvate and tetrakis(2-amino-5-methyl-1,3,4-thiadiazole-N4)platinum(II) hexachloroplatinate(IV) bis(N,N'-dimethylformamide) solvate.

The structures of the title compounds, [PtCl(2)(C(7)H(5)N(3)O(2)S)(2)].4C(3)H(7)NO, (I), and [Pt(C(3)H(5)N(3)S)(4)][PtCl(6)].2C(3)H(7)NO, (II), respectively, comprise square-planar Pt(II) centres. In the cation and anion of (II), the Pt atoms lie on independent inversion centres. For (I), the metal atom is N-bonded to two trans organic ligands and also bonded to two Cl atoms, whereas in (II), the Pt atom is N-bonded to four organic ligands, the charge being balanced by the presence of an additional [PtCl(6)](2-) species (from the starting material). Both structures contain dimethylformamide solvate molecules, four in the asymmetric unit of (I) and one in (II), which are involved in the hydrogen-bonding network via N-H.X and C-H.X associations.

Tetrakis(2-amino-5-methyl-1,3,4-thiadiazole-N3)chlorocopper(II) chloride monohydrate and tetrakis(2-amino-5-ethyl-1,3,4-thiadiazole-N3)chlorocopper(II) chloride.

The structures of the title compounds, [CuCl(C(3)H(5)N(3)S)(4)]Cl.H(2)O, (I), and [CuCl(C(4)H(7)N(3)S)(4)]Cl, (II), comprise square-pyramidal Cu centres with four N-bound organic ligands filling the base positions, a Cl atom in the apical position and a Cl(-) as a free counter-ion. The cation and free chloride ion in (II) have fourfold crystallographic symmetry. Hydrogen-bonding associations from the 2-amino H atoms dominate both structures, with the principal acceptors being the chlorides, although in (I), the N4 atoms are also involved. Furthermore, (I) is a hydrate, with the water molecule participating in the hydrogen-bonding network.

2-amino-4-(4-pyridyl)pyrimidine and the 1:1 adduct with 4-aminobenzoic acid.

The structure of the title compound, C9H8N4, comprises non-planar molecules that associate via pyrimidine N--H...N dimer R2(2)(8) hydrogen-bonding associations [N...N 3.1870 (17) A] and form linear hydrogen-bonded chains via a pyrimidine N--H...N(pyridyl) interaction [N...N 3.0295 (19) A]. The dihedral angle between the two rings is 24.57 (5) degrees. The structure of the 1:1 adduct with 4-aminobenzoic acid, C9H8N4*C7H7NO2, exhibits a hydrogen-bonding network involving COOH...N(pyridyl) [O...N 2.6406 (17) A], pyrimidine N--H...N [N...N 3.0737 (19) and 3.1755 (18) A] and acid N--H...O interactions [N...O 3.0609 (17) and 2.981 (2) A]. The dihedral angle between the two linked rings of the base is 38.49 (6) degrees and the carboxylic acid group binds to the stronger base group in contrast to the (less basic) complementary hydrogen-bonding site.

2-Amino-5-chloro-1,3-benzoxazol-3-ium 2-(3,4-dichlorophenoxy)acetate.

The 1:1 organic salt of the title compound, C(7)H(6)ClN(2)O(+). C(8)H(5)Cl(2)O(3)(-) or [(2-ABOX)(3,4-D)], comprises the two constituent molecules associated by an R(2)(2)(8) graph-set interaction through the carboxylate group of 3,4-D across the protonated N/N sites of 2-ABOX [N.O 2.546 (3) and 2.795 (3) A]. Cation/anion pairs associate across an inversion centre forming discrete tetramers via an additional three-centre hydrogen-bonding association from the latter N amino proton to a phenoxy O atom [N.O 3.176 (3) A] and a carboxylate O atom [N.O 2.841 (3) A]. This formation differs from the polymeric hydrogen-bonded chains previously observed for adduct structures of 2-ABOX with carboxylic acids.

The 1:1 adduct of 4-aminobenzoic acid with 4-aminobenzonitrile.

The 1:1 adduct of 4-aminobenzoic acid (PABA) with 4-am-inobenzonitrile (PABN), C(7)H(7)NO(2).C(7)H(6)N(2), consists of a primary centrosymmetric cyclic hydrogen-bonded PABA dimer interaction [O.O 2.640 (3) A] peripherally linked into chains by weaker hydrogen bonds via a head-to-tail PABN interaction [N.N 3.179 (4) and N.O 3.062 (4) A], and is linked between the chains by amine-N (PABN) to amine-N (PABA) interactions [N.N 3.233 (5) A]. No proton transfer occurs.

Crystal structure of a calcium-phospholipid binding domain from cytosolic phospholipase A2.

Cytosolic phospholipase A2 (cPLA2) is a calcium-sensitive 85-kDa enzyme that hydrolyzes arachidonic acid-containing membrane phospholipids to initiate the biosynthesis of eicosanoids and platelet-activating factor, potent inflammatory mediators. The calcium-dependent activation of the enzyme is mediated by an N-terminal C2 domain, which is responsible for calcium-dependent translocation of the enzyme to membranes and that enables the intact enzyme to hydrolyze membrane-resident substrates. The 2.4-A x-ray crystal structure of this C2 domain was solved by multiple isomorphous replacement and reveals a beta-sandwich with the same topology as the C2 domain from phosphoinositide-specific phospholipase C delta 1. Two clusters of exposed hydrophobic residues surround two adjacent calcium binding sites. This region, along with an adjoining strip of basic residues, appear to constitute the membrane binding motif. The structure provides a striking insight into the relative importance of hydrophobic and electrostatic components of membrane binding for cPLA2. Although hydrophobic interactions predominate for cPLA2, for other C2 domains such as in "conventional" protein kinase C and synaptotagmins, electrostatic forces prevail.

A ternary metal binding site in the C2 domain of phosphoinositide-specific phospholipase C-delta1.

We have determined the crystal structures of complexes of phosphoinositide-specific phospholipase C-delta1 from rat with calcium, barium, and lanthanum at 2.5-2.6 A resolution. Binding of these metal ions is observed in the active site of the catalytic TIM barrel and in the calcium binding region (CBR) of the C2 domain. The C2 domain of PLC-delta1 is a circularly permuted topological variant (P-variant) of the synaptotagmin I C2A domain (S-variant). On the basis of sequence analysis, we propose that both the S-variant and P-variant topologies are present among other C2 domains. Multiple adjacent binding sites in the C2 domain were observed for calcium and the other metal/enzyme complexes. The maximum number of binding sites observed was for the calcium analogue lanthanum. This complex shows an array-like binding of three lanthanum ions (sites I-III) in a crevice on one end of the C2 beta-sandwich. Residues involved in metal binding are contained in three loops, CBR1, CBR2, and CBR3. Sites I and II are maintained in the calcium and barium complexes, whereas sites II and III coincide with a binary calcium binding site in the C2A domain of synaptotagmin I. Several conformers for CBR1 are observed. The conformation of CBR1 does not appear to be strictly dependent on metal binding; however, metal binding may stabilize certain conformers. No significant structural changes are observed for CBR2 or CBR3. The surface of this ternary binding site provides a cluster of freely accessible liganding positions for putative phospholipid ligands of the C2 domain. It may be that the ternary metal binding site is also a feature of calcium-dependent phospholipid binding in solution. A ternary metal binding site might be a conserved feature among C2 domains that contain the critical calcium ligands in their CBR's. The high cooperativity of calcium-mediated lipid binding by C2 domains described previously is explained by this novel type of calcium binding site.