Oxazoles in carboxylate protection and activation

Wasserman, Harry H.; McCarthy, Keith E.; Prowse, K. S.

doi:10.1021/cr00075a008

Cited by 84 publications

(41 citation statements)

References 24 publications

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Section: Introductionmentioning

confidence: 99%

“…Over the last several years, a great deal of effort has been directed towards understanding the properties and functions of these enzymes. Most work with glucan syntheses has been performed using isolated membrane fractions from various plant and microbial sources (5, 9,16,27,28, 30).To date, glucan syntheses have proven to be extremely difficult to purify. One problem has been stability in detergent (2,12,13,21,26 Membrane Isolation.…”

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confidence: 99%

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Partial Purification of Digitonin-Solubilized β-Glucan Synthase from Red Beet Root

Eiberger

Wasserman²

1987

Plant Physiol.

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An enriched glucan synthase fraction was obtained from red beet root microsomes by sequential extraction with the detergents 3-1(3-cholamidopropyl)dimethylammoniol-l-propanesulfonate and digitonin. The digitonin suspension was centrifuged on a glycerol gradient, where a glucan synthase peak with a specific activity of 30-to 40-fold over microsomes was recovered. Most protein contaminants were found in the gradient pellet. The glucan synthase-containing fraction was largely free of plasma membrane and tonoplast-derived ATPase activity and was enriched with a protein subunit of 68 kilodaltons.Membrane-bound f,-glucan syntheses are a class of enzymes believed to be important in cell wall biosynthesis. Over the last several years, a great deal of effort has been directed towards understanding the properties and functions of these enzymes. Most work with glucan syntheses has been performed using isolated membrane fractions from various plant and microbial sources (5, 9,16,27,28, 30).To date, glucan syntheses have proven to be extremely difficult to purify. One problem has been stability in detergent (2,12,13,21,26 Membrane Isolation. Microsomes were isolated as previously described (8, 30).Glucan Synthase Assay. Glucan synthase assays were conducted in 100 ul assay mixtures containing 1 mm UDP-['4C] glucose (0.1 mCi per mmol), 5 mM MgCl2, 5 mm cellobiose, and 50 mM Tris-HCl (pH 7.0). The level of protein used varied between 2 and 50 tig, depending on the relative purity of the sample to be assayed. The mixtures were incubated at 30°C for 5 min and the reactions were then terminated by heating at 90 to 100°C for 10 min. Glucose incorporation was measured by the method of Smith and Stone (1975) as follows: Each reaction mixture was spotted on a Whatman GF/A filter disk (2.4 cm diameter), dried, and placed in a culture tube.The tubes were placed on ice and washed successively with 10 ml of 66% (w/v) ethanol containing 0.85 mm EDTA, 10 ml of 66% (w/v) ethanol, and 10 ml of 70% ethanol. Filters were rinsed with acetone, air dried, and counted. Quenching was corrected by counting known amounts of UDP-['4C]glucose that had been spotted on filters.Protein Determinations. Protein concentrations were measured by the Coomassie blue protein assay (7).Extraction of Microsomes with Digitonin. To solutions containing microsomes (0.85-2.0 ml) at protein concentrations of 2.4 to 5.3 mg per ml, an equal volume of a buffer containing 2% (w/v) digitonin, 5 mM MgCl2, and 50 mM Tris-HCl (pH 7.0) was added dropwise with stirring. The Glycerol Density Gradient Centrifugation. Linear gradients were made by combining 1.75 ml each of 12% (w/w) and 60% (w/w) glycerol in 5 mM MgCl2, 0.1 % digitonin, and 50 mM Tris-HCI (pH 7.0) on a gradient maker. In one experiment (Fig. 1), a www.plantphysiol.org on May 10, 2018 -Published by Downloaded from

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Partial Purification of Digitonin-Solubilized β-Glucan Synthase from Red Beet Root

Eiberger

Wasserman²

1987

Plant Physiol.

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“…[1][2][3][4][5][6][7][8][9][10] Gledano kroz povijest oksazoli su prisutni od 1887. godine kada je A. R. Hantzsch dao ime do tada maloj skupini spojeva. Oksazoli su peteročlani heterocikli s dva heteroatoma u prstenu, kisikom na položaju 1 te duši-kom na položaju 3 ili položaju 2 (slika 1).…”

Section: Uvod **unclassified

“…1 -Structures of oxazole (1), isoxazole (2), benzoxazole (3) and benzisoxazole (4) Većina sinteza oksazola tijekom sljedećih stotinu godina bila je usmjerena na sinteze alkilnih i arilnih derivata. Vrlo važna prekretnica u kemiji oksazola dogodila se 1940. godine kad je počelo opsežno istraživanje penicilina.…”

Section: Uvod **unclassified

Reakcije oksazola i njihovih derivata u pobuđenom stanju. I. dio: Fototranspozicije u prstenu

Šagud

Šindler‐Kulyk

2018

Kem. Ind.

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Heterocyclic compounds are a very important part of organic chemistry. Oxazole is a five-membered heterocycle with nitrogen and oxygen atoms in the ring. Oxazole is part of complex structures used in medicinal chemistry, pharmacology, and material chemistry. In the excited state, the oxazole ring can rearrange itself via several reaction mechanisms. In this paper, an extensive literature overview is given for photoisomerisations (phototranspositions) in oxazole, isoxazole, and benzisoxazole ring. A literature review is also given for phototransformations of the ring in the presence of oxygen (photooxygenation reactions), as well as for photoformation of the oxazole ring.

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“…The well-known occurrence of substituted pyrrole shape amongst biologically important natural products and pharmaceuticals has stimulated great interest in its synthetic methods [31]. Oxazoles continue to hold a center stage in organic synthesis, although the structure of the first oxazole was reported over a century ago [32]. The field of oxazoles is extensive and includes natural products, medicinal chemistry, and materials science.…”

Section: Introductionmentioning

confidence: 99%

Computational Studies and Energies for the Dioxa-Pentaazaheptacyclo-Hentriaconta-Octaen-One through Density Functional Theory and Natural Bond Orbital

Shahbazi¹,

Ghammamy²

2014

UCMS

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Abstract:In this paper, the molecular structure and electronic properties of 2, 18,19,20,20.01,8.03,7.09,14.024,11,13,17(31),18,24,26, were calculated by the B3LYP density functional model using 6-31G, 6-311G, 6-311++G and 6-311++G(d,p) basis sets. B3LYP calculation results indicated some selected bond length and bond angle values for this molecule. The optimized geometries and frequencies of the stationary point and the minimum-energy of this structure were recognized. The obtained results were compared with the corresponding experimental data. Trustworthiness of this results is confirmed by good agreement with the experimental analyzes of this structure. The results obtained by different basis sets were compared and the necessity of correlation methods for studying these systems is discussed.

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Oxazoles in carboxylate protection and activation

Cited by 84 publications

References 24 publications

Partial Purification of Digitonin-Solubilized β-Glucan Synthase from Red Beet Root

Partial Purification of Digitonin-Solubilized β-Glucan Synthase from Red Beet Root

Reakcije oksazola i njihovih derivata u pobuđenom stanju. I. dio: Fototranspozicije u prstenu

Computational Studies and Energies for the Dioxa-Pentaazaheptacyclo-Hentriaconta-Octaen-One through Density Functional Theory and Natural Bond Orbital

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