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Buschmann, Hans‐Jürgen; Cleve, E.; Jansen, K.; Wego, Andreas; Schollmeyer, Eckhard

doi:10.1023/a:1011159119554

Cited by 98 publications

(85 citation statements)

References 11 publications

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“…37 The latter are capable, not only for CB7 but also for its homologues, of binding inorganic cations as well as the cationic sites of organic guests, mostly ammonium groups; nonpolar groups are preferentially immersed in the inner cavity. [38][39][40][41][42] CB7 and its larger homologue CB8 have been shown to bind aromatic amino acids and sequence-specifically to peptides and proteins containing phenylalanine (Phe), tryptophan (Trp), or tyrosine (Tyr) at the N-terminal positions. [43][44][45][46][47] Recognition at the N terminus is achieved via the cooperation of hydrophobic inclusion of the aromatic side chain and electrostatic stabilization of the proximal N-terminal ammonium group.…”

Section: Resultsmentioning

confidence: 99%

Determining Protease Substrate Selectivity and Inhibition by Label-Free Supramolecular Tandem Enzyme Assays

et al. 2011

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An analytical method has been developed for the continuous monitoring of protease activity on unlabelled peptides in real time by fluorescence spectroscopy. The assay is enabled by a reporter pair comprising the macrocycle cucurbit [7]uril (CB7) and the fluorescent dye acridine orange (AO). CB7 functions by selectively recognizing N-terminal phenylalanine residues as they are produced during the enzymatic cleavage of enkephalintype peptides by the metalloendopeptidase thermolysin. The substrate peptides (e.g., ThrGly-Ala-Phe-Met-NH2) bind to CB7 with moderately high affinity (K ca. 10 4 M -1 ), while their cleavage products (e.g., Phe-Met-NH2) bind very tightly (K > 10 6 M -1 ). AO signals the reaction upon its selective displacement from the macrocycle by the high affinity product of proteolysis. The resulting supramolecular tandem enzyme assay effectively measures the kinetics of thermolysin, including the accurate determination of sequence specificity (Ser and Gly instead of Ala), stereospecificity (DAla instead of LAla), endo-versus exopeptidase activity (indicated by differences in absolute fluorescence response), and sensitivity to terminal charges (-CONH2 versus -COOH). The capability of the tandem assay to measure protease inhibition constants was demonstrated on phosphoramidon as a known inhibitor to afford an inhibition constant of (17.8 ± 0.4) nM. This robust and label-free approach to the study of protease activity and inhibition should be transferable to other endo-and exopeptidases that afford products with N-terminal aromatic amino acids.2

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Section: Resultsmentioning

confidence: 99%

Determining Protease Substrate Selectivity and Inhibition by Label-Free Supramolecular Tandem Enzyme Assays

et al. 2011

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“…It is well known that metal cations coordinate to both portals of the barrel-shaped CB [6] to give a dicationic complex. One CB [6] can bind with two sodium ions by ion-dipole interaction in aqueous solution to form complex of Na + CB[6]Na + [28]. Each alginate is a long chain with hundreds of carboxyl.…”

Section: Modes Of Formation Of Alginate/cb[6] Gel Beadsmentioning

confidence: 99%

Fabrication of cucurbit[6]uril mediated alginate physical hydrogel beads and their application as a drug carriers

et al. 2008

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Abstract:A novel cucurbit [6]uril (CB[6]) mediated alginate physical hydrogel bead was prepared for the first time, which is based on the electrostatic attraction and ion-dipole interaction between sodium alginate and CB [6]. These alginate/CB[6] gel beads are useful in controlled drug delivery and other biomedical applications. The potential of alginate/CB[6] gel beads as carrier for 5-Fluorouracil (5-Fu) was studied in this paper. The properties of alginate/CB[6] gel beads were studied by FT-IR, XRD and TGA. The process of the formation of alginate/CB[6] gel beads was recorded by Digital cameras. The external morphology of the dried beads were observed using SEM. Alginate/CB[6] gel beads first was formed as a thin film on the surface of the alginate solution droplet, holding its spherical shape. The color of the alginate/CB[6] gel beads changed from almost colorless to white with the increase of gel time, and also the beads became small and compact. The dried alginate/CB[6] gel beads were about 900-1000 µm, irregular spherical and the surface of dried beads showed a corrugated surface having a uniform distribution of regular nodules and cavities.

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“…Esta banda, no entanto, costuma deslocar-se para maiores comprimentos de onda quando ligada a metais, passando a constar em torno de 200 nm 29,30 . A espectroscopia de RMN é a mais empregada na caracterização destes compostos, que são solubilizados em misturas de ácidos e água deuterados.…”

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Cucurbiturilas

Demets¹

2007

Quím. Nova

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Recebido em 7/8/06; aceito em 9/11/06; publicado na web em 17/7/07 CUCURBITURILS. This review article describes the properties and the main applications of the glicol[n]urils. These compounds are cavitands made of n glycolurilic units arranged in circles, giving rise to extremely symmetric toroidal molecules. The cucurbit [n]urils create this way variable-sized hydrophobic cavities and the glycolurilic carbonyles delimit two portals on these cavities, slightly narrower than their internal radii. Their structure, physical and chemical properties favor the formation of inclusion compounds, and turn them into important building blocks for supramolecular chemistry and nanotechnology.Keywords: cucurbiturils; cucurbitands; inclusion compounds. INTRODUÇÃOAs cucurbiturilas foram sintetizadas pela primeira vez por Behrend e colaboradores 1 em 1905, como resultado da condensação da uréia e do glioxal, formando glicolurila e análogos poliméricos na presença de formaldeído. A tecnologia da época não permitiu uma caracterização inequívoca e a estrutura peculiar destes polímeros só foi elucidada pelo grupo de Mock, 80 anos mais tarde 2 . Pela primeira vez demonstrou-se que os cucurbitandos, outra designação desta família de compostos (abreviados também por CB[n]), eram estruturas cíclicas toroidais, compostas por 6 unidades de glicolurila, ligadas por grupos -CH 2 -em suas aminas de simetria D 6H (Figura 1).A nomenclatura oficial deste composto é complexa* e a sua forma de abóbora deu origem a seu nome, de cucurbita em latim (* segundo a IUPAC, o nome da cucurbit[6]urila ou CB[6] seria: dodecaidro-1H, 4H, 14H, 17H-2, 16:3, 15-dimetano-5H, 6H, 7H, 8H, 9H, 10H, 11H, 12H, 13H, 18H, 19H, 20H, 21H, 22H, 23H, 24H, 25H, 26H-2, 3-4a, 5a, 6a, 7a, 8a, 9a, 10a, 11a, 12a, 13a, 15, 16, 17a, 18a, 19a, 20a, 21a, 22a, 23a, 24a, 2 -3 -5a, 26a -tetracosaazabispentaleno[1''',6''':5'',6'',7'']cicloocta[1'', 2'', 3'':3', 4']pentaleno(1',6':5,6,7)cicloocta(1,2,3-gh:1',2',3'-g'h')cicloocta(1, 2, 3-cd:5, 6, 7-c'd')dipentaleno-1, 4, 6, 8, 10, 12, 14, 17, 19, 21, 23, 25-dodecona).Esta estrutura, além de ser simétrica, possui uma cavidade central hidrofóbica relativamente grande, que é capaz de acomodar espécies variadas para a formação de compostos de inclusão, também chamados de caviplexos, como o fazem outras famílias de cavitandos como as ciclodextrinas ou calixarenos. Na cucurbit[6]urila, existem 12 carbonilas orientadas para fora das cavidades, 6 de cada lado, formando assim dois portais para as cavidades, e conferindo à molé-cula um caráter básico de Lewis. Os métodos mais modernos de análise constataram que não eram formados apenas anéis de 6 membros nas sínteses de cucurbiturilas, mas que outros análogos cíclicos com 5 a 11 unidades glicolurílicas também eram formados durante as sínteses. Os recentes avanços em química orgânica sintética permitiram a elaboração de novas rotas, resultando em rendimentos diferenciados na produção destes homólogos. O maior controle sobre a distribuição dos produtos síntese tornou viável a síntese de CB [7] e ...

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Cited by 98 publications

References 11 publications

Determining Protease Substrate Selectivity and Inhibition by Label-Free Supramolecular Tandem Enzyme Assays

Determining Protease Substrate Selectivity and Inhibition by Label-Free Supramolecular Tandem Enzyme Assays

Fabrication of cucurbit[6]uril mediated alginate physical hydrogel beads and their application as a drug carriers

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