Changes in the chemistry of an isoalloxazine brought about by substitution at the 7 and 8 positions by a strongly electronegative substituent

Tc, Bruice; Tw, Chan; Jp, Taulane; Yokoe, Ichiro; Dl, Elliott; Rf, Williams; Novák, Michael

doi:10.1021/ja00462a040

Cited by 40 publications

(18 citation statements)

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“…The spectral changes that were observed are similar to those of the cyanoisoalloxazine observed by Bruice et al (13) and compatible with formation of a spirohydantoin (30). As is the case with the cyanoisoalloxazine derivative, repetitive spectral scans during the hydrolysis failed to provide any evidence for the 10a-or 4a-hydroxyl adducts, which were considered as possible intermediate species during hydrolysis.…”

Section: Hydrolysis Of 8-cn-riboflavinsupporting

confidence: 82%

“…The reduction is fully reversible with oxygen. However the spectrum for reduced 8-CN-riboflavin is different from that of normal flavin, as reported previously for 8-CN-7-nor-3-methyl-lumiflavin by Bruice et al (13). Reduced 8-CN-riboflavin has two well defined peaks above the 300 nm region with maxima at 312 and 372 nm at pH 7 and at 316 and 362 nm under acidic conditions (Fig.…”

Section: Reduction Of 8-cn-riboflavinsupporting

confidence: 77%

“…Accordingly these properties have been exploited to advantage in determining the solvent accessibility of the 8-position of the flavin in various flavoproteins (9) and also for the covalent labeling of active site amino acid residues (10 -12). Elegant model studies by Bruice et al (13) with 8-CN-isoalloxazines have demonstrated that cyanylation at the 8-position affords an isoalloxazine with one of the highest known potentials along with very interesting chemical and spectral properties. Although the CN functionality is strongly electronegative, it is resistant to displacement reactions, since these would involve carbon-carbon bond breaking.…”

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confidence: 99%

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Synthesis and Properties of 8-CN-flavin Nucleotide Analogs and Studies with Flavoproteins

Murthy

Massey

1998

Journal of Biological Chemistry

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A high potential analog of riboflavin with a cyano function at the 8-position was synthesized by employing novel reaction conditions, starting from 8-amino-riboflavin. This was converted to the FAD level with FAD synthetase. The reduced 8-CN-riboflavin, unlike normal reduced flavin, has a distinctive absorption spectrum with two distinctive peaks in the near ultraviolet region. The oxidation-reduction potential of the new flavin was determined to be -50 mV, ϳ160 mV more positive than that of normal riboflavin. The 8-CN-riboflavin and 8-CN-FMN were found to be photoreactive and need to be protected from exposure to light. However such complications were not encountered with protein-bound flavins. The apoproteins of flavodoxin and Old Yellow Enzyme (OYE) were reconstituted with the 8-CN-FMN and apoDAAO was reconstituted with 8-CN-FAD. Spectral properties of the enzyme-bound neutral and anionic semiquinones were determined from these reconstituted proteins. In the case of 8-CN-FMN-OYE I, it was shown that the comproportionation reaction of a mixture of reduced and oxidized enzyme bound flavin is very rapid, compared with the same reaction with native protein, resulting in ϳ100% thermodynamically stable anionic semiquinone. In the case of 8-CN-OYE I, it was shown that the rate of reduction of the enzyme bound flavin by NADPH is ϳ40 times faster, and the rate of reoxidation of reduced enzyme bound flavin by oxygen is an order of magnitude slower than with the normal FMN enzyme. This is in accord with the high oxidation-reduction potential of the flavin, which thermodynamically stabilizes the reduced enzyme.

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Section: Hydrolysis Of 8-cn-riboflavinsupporting

confidence: 82%

Section: Reduction Of 8-cn-riboflavinsupporting

confidence: 77%

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confidence: 99%

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Synthesis and Properties of 8-CN-flavin Nucleotide Analogs and Studies with Flavoproteins

Murthy

Massey

1998

Journal of Biological Chemistry

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“…Method (i) is exemplified by (3.70)-(3.73) (Yokoe and Bruice, 1975;Bruice et al, 1977;Knappe, 1979;Shinkai etal., 1979f;Yano etal., 1984), in which the electron-withdrawing substituents enhance the electron-deficiency of the isoalloxazine ring. Method (i) is exemplified by (3.70)-(3.73) (Yokoe and Bruice, 1975;Bruice et al, 1977;Knappe, 1979;Shinkai etal., 1979f;Yano etal., 1984), in which the electron-withdrawing substituents enhance the electron-deficiency of the isoalloxazine ring.…”

Section: Flavins As Oxidation Catalystsmentioning

confidence: 99%

Enzyme Chemistry

1990

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“…We therefore made it from the amine 4a by conversion to its bis-trifluoroacetamide 4c (18). Although such amides are reported (19,20) to give secondary amines directly on treatmentwith methyl iodide-and potassium hydroxide, with this compound we isolated the N,Nr-dimethyl bis-trifluoroacetamide (4d) which afforded 46 on prolonged alkaline hydrolysis. When this was treated with N-sulfinylmethanesulfonamide we were unable to isolate any isothiazole products.…”

Section: Introductionmentioning

confidence: 99%

The preparation of some fused isothiazole derivatives

McKinnon¹,

Duncan²,

McKinnon³

et al. 1985

Can. J. Chem.

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Can. J. Chem. 63, 882 (1985). The treatment of di(2-amino-5-methy1phenyl)methane with N-sulfinylmethanesulfonamide gives two materials, 3-(2-amino-5-methylpheny1)-5-methyl-?, I -benzisothiazole and what appears to bc its tautomer, a 2,l -benzisothiazolo[2,3-b]-2, I-benzisothiazole derivative. Reaction of the former with methyl iodide gives mono-, di-, and trimethyl derivatives. The second of these also possesses the symmetrical 2, I -benzisothiazolo[2,3-b]-2, I -benzisothiazole structure. The structure of the other methylation product and of the acetylation products are discussed. Some 1.2-dithiol-3-ylidene-2-pyridylmethanes were made by condensation of 3-alkylthio-l,2-dithiolium salts with methyl 2-pyridylacetate. These demonstrate little sulfur-nitrogen interaction. 3-Methylthio-4-phenyl-I ,2-dithiolium iodide reacts anomalously with methyl 2-pyridylacetate to form a quinolizinethione. I .2-Benzisothiazolo[2,3-o]pyridinium triiodide was made by iodine oxidation of 2-(2-mercaptophenylpyridine).

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Changes in the chemistry of an isoalloxazine brought about by substitution at the 7 and 8 positions by a strongly electronegative substituent

Cited by 40 publications

References 4 publications

Synthesis and Properties of 8-CN-flavin Nucleotide Analogs and Studies with Flavoproteins

Synthesis and Properties of 8-CN-flavin Nucleotide Analogs and Studies with Flavoproteins

Enzyme Chemistry

The preparation of some fused isothiazole derivatives

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