Jiménez-Díaz M, Martínez-Monge V

Language: Spanish
References: 15
Page: 91-98
PDF size: 48.54 Kb.

ABSTRACT

Introduction. A kinetic method for the determination of plasma cholinesterase, which entails the use of 6,6‘-dithiodinicotinic acid as a chromogen is validated.
Material and methods. In this procedure, the hydrolysis of propionylthiocholine liberates thiocholine, that reacts with 6-6‘-dithiodinicotinic acid (DTNA) to yield thionicotinic acid, which has an optimal absorption wavelength at 340 nm. The increase in absorbance at 340 nm is proportional to enzyme activity.
Results. The CV of the between run precision ranged from 3,5 to 4,2 per cent. Within-run precision ranged from 1,5 to 2,3 per cent. Bilirrubin and hemoglobin do not interfere. The working reagent, stored in an amber-colored bottle, is stable for at least 6 months at 4-8°C.
Comparisons with two commercial methods based on the Ellman‘s reaction, gave in the first case a linear regression of Y = 1.13 (X) - 274, with a correlation coefficient (r) of 0.987 and a standard error (S_y/x) of 345 U/L. In the second case the results were Y = 1.374 (X) + 240; r = 0.977; S_y/x = 491U/L.
Discussion. The evaluated method constitutes a precise and cheaper alternative for the determination of plasma cholinesterase. The data indicate that the method is linear and precise in the range of normal enzyme activity. Comparison with commercial methods gave a good correlation. The procedure has the great advantage that hemoglobin do not interfere.

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