Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q86TM3 (cage)
 29,987 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new polyamine macrobicyclic compound was synthesised through a [1+1] "tripod-tripod coupling" strategy and using a Schiff base condensation reaction, followed by sodium borohydride reduction. The resulting compound is a heteroditopic cage (btpN(7)) in which one of the head units is appropriate for the coordination of copper(II), whereas the other head is available for additional hydrogen-bonding and electrostatic interactions with substrates. The acid-base behaviour of the new compound, the stability constants of its complex with the Cu(2+) ion and the association constants of the copper(II) cryptate with oxalate (oxa(2-)), malonate (mal(2-)), succinate (suc(2-)), maleate (male(2-)) and fumarate (fum(2-)) were determined by potentiometry at 298.2 K in aqueous solution and at an ionic strength of 0.10 mol dm(-3) in KNO(3). These studies revealed a clear preference of the receptor [CuH(h)btpN(7)H(2)O]((2+h)+) for oxa(2-) over the other dicarboxylate substrates. This arises from co-operativity between metal-anion coordination and electrostatic and hydrogen-bonding interactions, in accordance with the ideal size of this dicarboxylate, which allow it to take full advantage of the potential binding sites of the receptor. A qualitative indicator-displacement study, in agreement with the potentiometric studies, demonstrated that the copper cryptate receptor can be used as a selective visual sensor for oxalate.
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PMID:Recognition of oxalate by a copper(II) polyaza macrobicyclic complex. 2155 58

Two chiral cage clusters built from uranyl polyhedra and (HPO(3))(2-) groups have been synthesized in pure yield and characterized structurally and spectroscopically in the solid state and aqueous solution. Synthesis reactions under ambient conditions in mildly acidic aqueous solutions gave clusters U(22)PO(3) and U(28)PO(3) that contain belts of four uranyl peroxide pentagonal and hexagonal bipyramids, in contrast to earlier reported uranyl peroxide cage clusters that are built from four-, five-, and six-membered rings of uranyl hexagonal bipyramids. U(22)PO(3) and U(28)PO(3) are also the first chiral uranyl-based cage clusters, the first that contain uranyl pentagonal bipyramids that contain no peroxide ligands, and the first that incorporate (HPO(3))(2-) bridges between uranyl ions. They are built from 22 uranyl polyhedra and 20 (HPO(3))(2-) groups, or 28 uranyl polyhedra and 24 (HPO(3))(2-) groups, with the outer and inner surfaces of the cages passivated by the O atoms of uranyl ions. Small-angle X-ray scattering (SAXS) profiles demonstrated that U(22)PO(3) clusters formed in solution within 1 h after mixing of reactants, and remained in solution for 2 weeks prior to crystallization. Time-resolved electrospray ionization mass spectrometry and SAXS demonstrated that U(28)PO(3) clusters formed in solution within 1 h of mixing the reactants, and remained in solution 1 month before crystallization. Crystallization of U(22)PO(3) and U(28)PO(3) is accelerated by addition of KNO(3). Clusters of U(22)PO(3) with and without encapsulated cations exhibit markedly different aqueous solubility, reflecting the importance of cluster surface charge in fostering linkages through counterions to form a stable solid.
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PMID:Time-resolved assembly of chiral uranyl peroxo cage clusters containing belts of polyhedra. 2323 90