The enthalpimetric determination of inhibition constants for the competitive inhibition of serum cholinesterase by morphine, quinine and procaine

1981 ◽  
Vol 21 (2) ◽  
pp. 367-373 ◽  
Author(s):  
B. Tan ◽  
J. K. Grime
Keyword(s):  
Competitive Inhibition ◽  
Serum Cholinesterase ◽  
Inhibition Constants

scholarly journals A quick method for the determination of inhibition constants

1982 ◽  
Vol 205 (3) ◽  
pp. 631-633 ◽  
Author(s):  
S G Waley
Keyword(s):  
Competitive Inhibition ◽  
Inhibition Constant ◽  
Quick Method ◽  
Mixed Inhibition ◽  
The Common ◽  
Inhibition Constants ◽  
The Difference ◽  
The Times ◽  
Substrate Concentrations

The inhibition constant Ki in the common case of competitive inhibition can be obtained by simple comparison of progress curves in the presence and in the absence of inhibitor. The difference between the times taken for the concentration of substrate to fall to the same value is used to obtain Ki. The procedure to use when the product inhibits is described. When there is mixed inhibition, reactions at different substrate concentrations are used to obtain both inhibition constants.

Colorimetric Method for the Determination of Serum Cholinesterase*

1952 ◽  
Vol 22 (11_ts) ◽  
pp. 1126-1133 ◽  
Author(s):  
J. de la Huerga ◽  
Charlotte Yesinick ◽  
Hans Popper
Keyword(s):  
Colorimetric Method ◽  
Serum Cholinesterase

scholarly journals A Basic Program for Serum Cholinesterase Phenotyping Using a Microcomputer

1984 ◽  
Vol 21 (1) ◽  
pp. 43-44
Author(s):  
Jane F Loughlin ◽  
J F Tuckerman ◽  
A R Henderson
Keyword(s):  
Reaction Rate ◽  
Basic Program ◽  
Serum Cholinesterase ◽  
Full Account

We have modified a basic program for serum cholinesterase phenotyping using a microcomputer. This program accepts the reaction-rate result of total and inhibitor assays of activity, allows the patient to be identified and prints out a full account of the fitting process thus allowing adequate documentation. We believe that this modification enhances the usefulness of the program to laboratories engaged in the routine determination of serum cholinesterase phenotyping.

scholarly journals Effect of anti-thyroid peroxidase (TPO) antibodies on TPO activity measured by chemiluminescence assay

1997 ◽  
Vol 43 (8) ◽  
pp. 1392-1396 ◽  
Author(s):  
V Kaczur ◽  
Gy Vereb ◽  
I Molnár ◽  
G Krajczár ◽  
E Kiss ◽  
...  
Keyword(s):  
Western Blotting ◽  
Competitive Inhibition ◽  
High Sensitivity ◽  
Inhibitory Effect ◽  
Thyroid Peroxidase ◽  
Chemiluminescence Detection ◽  
Chemiluminescence Method ◽  
Blotting Technique ◽  
Hypothyroid Patients

Abstract A chemiluminescence method was developed to measure thyroid peroxidase (TPO) activity and the inhibitory effect of anti-TPO antibodies in purified porcine TPO. The TPO preparation was characterized kinetically and controlled by Western-blotting technique. The chemiluminescence method proved to be reproducible and much more sensitive than the widely used guaiacol method, being able to detect TPO concentrations of 2.21 × 10−5 g/L vs 6.63 × 10−2g/L with the latter. Otherwise, the determinations with the two methods correlated well (r = 0.76). Investigating the effect of IgGs from 23 hypothyroid patients on measured TPO activity, we detected inhibition in 19 cases with the chemiluminescence technique (15 with the guaiacol method). Anti-TPO antibodies showed competitive inhibition of TPO activity with respect to the substrate guaiacol. In both systems, the inhibition is present in the IgG F(ab′)2 fragment. We conclude that the high sensitivity of chemiluminescence detection allows routine determination of the inhibition of TPO activity by anti-TPO antibodies.

Determination of Methyl 2-Benzimidazolecarbamate in Wine by Competitive Inhibition Enzyme Immunoassay

1993 ◽  
Vol 76 (4) ◽  
pp. 851-856 ◽  
Author(s):  
Rodney J Bushway ◽  
Lance R Paradis ◽  
Lewis B Perkins ◽  
Titan S Fan ◽  
Barbara E S Young ◽  
...  
Keyword(s):  
Enzyme Immunoassay ◽  
Competitive Inhibition ◽  
White Wines ◽  
Average Recovery ◽  
Total Analysis Time ◽  
Coefficients Of Variation ◽  
Limit Of Quantitation ◽  
Total Analysis ◽  
Commercial Kit

Abstract A benomyl polyclonal enzyme immunoassay (EIA) commercial kit was used to quantitate methyl 2- benzimidazolecarbamate (MBC), a degradation product of benomyl in wine. Total analysis time, including sample preparation, was 30 min. As many as 8 samples can be analyzed simultaneously with a limit of quantitation of 5 ppb. The assay logarithmic response was linear from 0.4 to 26 ppb MBC. Intra-assay percent coefficients of variation (%CVs) ranged from 2.4 to 13 for standards and from 7.4 to 21 for actual wine samples. Interassay %CVs varied from 2.6 to 15 for the standards and from 6.9 to 23 for the samples. Average recovery from samples spiked at 10–10 000 ppb was 93% for evaporated red and white wines. MBC was determined in 134 different wines by immunoassay and liquid chromatography (LC). Of these samples, 98 were positive for MBC by both methods with a correlation coefficient (r) of 0.986. The other 36 samples had MBC levels that either were not detectable by either procedure or were below the 10 ppb limit of quantitation for LC. Concentrations of MBC in wine ranged from 5 to 1329 ppb, with the majority ranging from 10 to 300 ppb. Also, a mini-study was conducted using the plate EIA format.

A METHOD FOR THE DETECTION OF ATYPICAL FORMS OF HUMAN SERUM CHOLINESTERASE. DETERMINATION OF DIBUCAINE NUMBERS

1957 ◽  
Vol 35 (6) ◽  
pp. 339-346 ◽  
Author(s):  
W. Kalow ◽  
K. Genest
Keyword(s):  
Human Serum ◽  
Local Anaesthetic ◽  
Phosphate Buffer ◽  
Esterase Activity ◽  
Experimental Temperature ◽  
Serum Cholinesterase ◽  
Good Discrimination ◽  
Esterase Inhibition ◽  
Recording Spectrophotometer

Cases with atypical esterase activity were found by determining esterase inhibition in numerous sera. A suitable inhibitor was the local anaesthetic dibucaine (cinchocaine, TN Nupercaine, Perkain). A good discrimination between typical and atypical sera was obtained under the following conditions: The esterase activity of human serum diluted 1:100 was measured with a recording spectrophotometer at 240 mμ. The substrate was 5 × 10−5 M benzoylcholine dissolved in M/15 phosphate buffer, pH 7.4. The concentration of the inhibitor was 10−5 M. With the experimental temperature around 25 °C, the average inhibition of the typical enzyme was 78.8 ± 0.3%. The inhibition of the atypical esterases was less; in rare cases the inhibition was only 16%. For each person, the inhibition characteristics were constant over a period of several months, and independent of the esterase level. The degree of inhibition measured under these conditions and expressed in per cent has been termed "Dibucaine Number".

A METHOD FOR THE DETECTION OF ATYPICAL FORMS OF HUMAN SERUM CHOLINESTERASE. DETERMINATION OF DIBUCAINE NUMBERS

1957 ◽  
Vol 35 (1) ◽  
pp. 339-346 ◽  
Author(s):  
W. Kalow ◽  
K. Genest
Keyword(s):  
Human Serum ◽  
Local Anaesthetic ◽  
Phosphate Buffer ◽  
Esterase Activity ◽  
Experimental Temperature ◽  
Serum Cholinesterase ◽  
Good Discrimination ◽  
Esterase Inhibition ◽  
Recording Spectrophotometer

Cases with atypical esterase activity were found by determining esterase inhibition in numerous sera. A suitable inhibitor was the local anaesthetic dibucaine (cinchocaine, TN Nupercaine, Perkain). A good discrimination between typical and atypical sera was obtained under the following conditions: The esterase activity of human serum diluted 1:100 was measured with a recording spectrophotometer at 240 mμ. The substrate was 5 × 10−5 M benzoylcholine dissolved in M/15 phosphate buffer, pH 7.4. The concentration of the inhibitor was 10−5 M. With the experimental temperature around 25 °C, the average inhibition of the typical enzyme was 78.8 ± 0.3%. The inhibition of the atypical esterases was less; in rare cases the inhibition was only 16%. For each person, the inhibition characteristics were constant over a period of several months, and independent of the esterase level. The degree of inhibition measured under these conditions and expressed in per cent has been termed "Dibucaine Number".

scholarly journals Progress-curve equations for reversible enzyme-catalysed reactions inhibited by tight-binding inhibitors

1990 ◽  
Vol 265 (3) ◽  
pp. 647-653 ◽  
Author(s):  
S E Szedlacsek ◽  
V Ostafe ◽  
R G Duggleby ◽  
M Serban ◽  
M O Vlad
Keyword(s):  
Linear Regression ◽  
Competitive Inhibition ◽  
Tight Binding ◽  
The Other ◽  
First Order ◽  
Regression Methods ◽  
Progress Curve ◽  
Dead End ◽  
Non Linear ◽  
Inhibition Constants

The rate equation for a tight-binding inhibitor of an enzyme-catalysed first-order reversible reaction was used to derive two integrated equations. One of them covers the situations in which competitive, uncompetitive or non-competitive inhibition occurs and the other refers to the special non-competitive case where the two inhibition constants are equal. For these equations, graphical and non-linear regression methods are proposed for distinguishing between types of inhibition and for calculating inhibition constants from progress-curve data. The application of the non-linear regression to the analysis of stimulated progress curves in the presence of a tight-binding inhibitor is also presented. The results obtained are valid for any type of ‘dead-end’-complex-forming inhibitor and can be used to characterize an unknown inhibitor on the basis of progress curves.

scholarly journals Interaction of the lacZ β-galactosidase of Escherichia coli with some β-d-galactopyranoside competitive inhibitors

1979 ◽  
Vol 177 (1) ◽  
pp. 145-152 ◽  
Author(s):  
R. S. Thomas Loeffler ◽  
Michael L. Sinnott ◽  
Brian D. Sykes ◽  
Stephen G. Withers
Keyword(s):  
Escherichia Coli ◽  
Competitive Inhibition ◽  
Phenolic Hydroxy Group ◽  
Bivalent Metal ◽  
Transverse Relaxation ◽  
Competitive Inhibitors ◽  
Inhibition Constants ◽  
Increasing Temperature ◽  
Phenolic Hydroxy ◽  
Average Position

1. The location of the bivalent metal cation with respect to bound competitive inhibitors in Escherichia coli (!lacZ) β-galactosidase was investigated by proton magnetic resonance. 2. Replacement of Mg2+ by Mn2+ enhances both longitudinal and transverse relaxation of the methyl groups of the β-d-galactopyranosyltrimethylammonium ion, and of methyl 1-thio-β-d-galactopyranoside; linewidths are narrowed by increasing temperature. 3. The Mn2+ ion is located 8–9Å (0.8–0.9nm) from the centroid of the trimethylammonium group and 9Å (0.9nm) from the average position of the methylthio protons. 4. The effective charge at the active site was probed by measurement of competitive inhibition constants (Kio and Ki+ respectively) for the isosteric ligands, β-d-galactopyranosylbenzene and the β-d-galactopyranosylpyridinium ion. 5. The ratio of inhibition constants (Q=Ki+/Kio) obtained with 2-(β-d-galactopyranosyl)–naphthalene and the β-d-galactopyranosylisoquinolinium ion at pH7 with Mg2+–enzyme was identical, within experimental error, with that obtained with the monocyclic compounds. 6. The variation of Q for Mg2+–enzyme can be described by Q=0.1(1+[H+]/4.17×10−10)/1+[H+]/10−8). 7. This, in the theoretical form for a single ionizable group, is ascribed to the ionization of the phenolic hydroxy group of tyrosine-501. 8. The variation of Q for Mg2+-free enzyme is complex, probably because of deprotonation of the groups normally attached to Mg2+ as well as tyrosine-501.

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