Erratum: Assisted hydrolysis of cis-2-(3-phenylthioureido)cyclopentane-carbonitrile in alkaline solution. Solvent dependent switch from hydrolysis to rearrangement of the iminothiooxopyrimidine intermediate

The hydrolysis of maleimide has been investigated in the pH range 8.5–14. Polarographic limiting currents were well-defined, so that the bulk concentration of reactant during reduction could be clearly followed as a function of time. Logarithmic analysis of derived data indicated an arrest in the rate of reaction at circa pH 12, and a reaction scheme is proposed to explain this. In this scheme, the neutral maleimide molecule exists in equilibrium with its anion, and both of these species may undergo hydrolysis at the appropriate pH. From derived rate equations, the pKa of maleimide was found to be 10.0, whilst estimates of the rates of hydrolysis were also calculated.

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ESTIMATION OF CORTICOSTEROIDS BY THE REDUCTION OF FERRICYANIDE

Canadian Journal of Biochemistry and Physiology ◽

10.1139/y59-040 ◽

1959 ◽

Vol 37 (1) ◽

pp. 391-398 ◽

Cited By ~ 1

Author(s):

N. R. Stephenson

Keyword(s):

Prussian Blue ◽

Blood Sugar ◽

Alkaline Medium ◽

Alkaline Solution ◽

Reducing Power ◽

Hydroxyl Group ◽

Side Chain ◽

Inhibiting Effect ◽

Reducing Activity ◽

Hydrolysis Of

A procedure based on a modification of Folin's micromethod for blood sugar (1, 2) was used to investigate the reducing activity of various corticosteroids. The ferrocyanide produced as a result of the reduction of ferricyanide in alkaline solution was measured photometrically as Prussian blue. With a filter transmitting light at 620 mμ, the relation between the absorbance of the chromogen and the amount of the reducing steroid obeyed Beer's law over the range from 0.005 to 0.050 mg. The oxygen function at C-3 accounted for most of the reducing power of the non-alpha ketolic steroids studied. An oxygen function at C-11 did not affect significantly the reduction of ferricyanide by 17-desoxycorticosteroids. Although the presence of a hydroxyl at C-17 depressed the reducing activity of the alpha-ketol side chain, a fluorine at C-9 and an hydroxyl at C-11 appeared to overcome this inhibiting effect. Evidence was obtained to suggest that a C-16 hydroxyl group was able to increase the reducing action of the alpha-ketolic side chain. Esterification of the C-21 hydroxyl influenced the reduction of ferricyanide only when interference with hydrolysis of the ester in the alkaline medium was experienced.

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481. Simple and rapid methods for the estimation of bacterial phosphatases using di-sodium p–nitrophenylphosphate as substrate

Journal of Dairy Research ◽

10.1017/s002202990000649x ◽

1952 ◽

Vol 19 (3) ◽

pp. 275-287 ◽

Cited By ~ 5

Author(s):

J. Tramer

Keyword(s):

Alkaline Solution ◽

Bacterial Suspension ◽

Optimal Conditions ◽

Yellow Colour ◽

Rapid Methods ◽

Measured Amount ◽

Close Relationship ◽

Hydrolysis Of

Bacterial phosphatases of growing organisms can be simply demonstrated by incorporating di–sodium–p–nitrophenylphosphate (pNPP) into suitable media. The phosphatase content of a bacterial suspension can be assessed by incubating a measured amount of it with unbuffered or suitably buffered pNPP solutions. The yellow colour (in alkaline solution) of p-nitrophenol liberated from the substrate by phosphatase can be measured accurately and conveniently in a photoelectric absorptiometer, or estimated in a Lovibond comparator using permanent colour standards. The usefulness of the tests for differentiating between members of certain genera is demonstrated by the reactions of Bact. aerogenes and Bact. cloacae, for which a close relationship between phosphatase production and gelatine liquefaction times has been found. The optimal conditions for hydrolysis of pNPP by the phosphatase of a strain of Bact. aerogenes have been established.

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