Semiautomated Thiocyanate Method for Determining Peroxide Values of Lipids

Starkovich, John; Roubal, William T.

doi:10.1111/j.1365-2621.1969.tb00917.x

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…H 2 O 2 Production-The amount of H 2 O 2 formed was measured using an iron(II) thiocyanate assay as previously described (17). The standard reaction (50 mM Tris-HCl, pH 7.4) contained P450 (0.5 M), cindoxin (4 M), E. coli reductase (1 M), cineole (6 mM), and a known concentration of NADPH (ϳ1-2 mM).…”

Section: Methodsmentioning

confidence: 99%

The Critical Role of Substrate-Protein Hydrogen Bonding in the Control of Regioselective Hydroxylation in P450cin

Meharenna

Slessor

Cavaignac

et al. 2008

Journal of Biological Chemistry

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Cytochrome P450cin (CYP176A1) is a bacterial P450 isolated from Citrobacter braakii that catalyzes the hydroxylation of cineole to (S)-6␤-hydroxycineole. This initiates the biodegradation of cineole, enabling C. braakii to live on cineole as its sole source of carbon and energy. P450cin lacks the almost universally conserved threonine residue believed to be involved in dioxygen activation and instead contains an asparagine at this position (Asn-242). To investigate the role of Asn-242 in P450cin catalysis, it was converted to alanine, and the resultant mutant was characterized. The characteristic CO-bound spectrum and spectrally determined K D for substrate binding were unchanged in the mutant. The x-ray crystal structures of the substrate-free and -bound N242A mutant were determined and show that the only significant change is in a reorientation of the substrate such that (R)-6␣-hydroxycineole should be a major product. Molecular dynamics simulations of both wild type and mutant are consistent with the change in regio-and stereoselectivity predicted from the crystal structure. The mutation has only a modest effect on enzyme activity and on the diversion of the NADPHreducing equivalent toward unproductive peroxide formation. Product profile analysis shows that (R)-6␣-hydroxycineole is the main product, which is consistent with the crystal structure. These results demonstrate that Asn-242 is not a functional replacement for the conserved threonine in other P450s but, rather, is critical in controlling regioselective substrate oxidation.

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Section: Methodsmentioning

confidence: 99%

The Critical Role of Substrate-Protein Hydrogen Bonding in the Control of Regioselective Hydroxylation in P450cin

Meharenna

Slessor

Cavaignac

et al. 2008

Journal of Biological Chemistry

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“…One procedure using FIA for the automated determination of free fatty acids has been published by Lars-GSsta Ekstr~m (27). A thiocyanate method for determining the peroxide values of lipids using segmented flow was published in 1969 (28). This would lend itself readily to FIA.…”

Section: Laboratory Automationmentioning

confidence: 99%

Instrumental analytical methods for edible oil processing: Present and future

Sleeter

1983

J Americ Oil Chem Soc

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Current trends in analytical techniques for edible oil processing are reviewed. Major emphasis is placed on advances in instrumental and automated analyses. Future goals and priorities are also discussed. Some of the major analytical topics covered are: pulsed nuclear magnetic resonance, automated solid fat index, atomic absorption, automated active oxygen method, color, hydrogenation control, and gas liquid chromatography.

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“…2 ) The activity of I m mol dm -3 of I is similar to that of ascorbic acid. However, I did not show the anti oxidative activity in the auto-oxidation of linolenic acid.…”

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confidence: 92%