Disease relevance of KYNURAMINE

• Monoamine oxidase (MAO, E.C. 1.4.3.4) activity was determined by spectrophotofluorimetric assay of the reaction product of the artificial substrate kynuramine in platelets from venous blood samples from 50 outpatients with glaucomas and 47 sex- and age-matched controls [1].

High impact information on KYNURAMINE

• The Km value for kynuramine was essentially the same for mitochondria (0.12 mM) and enzyme after DEAE-Sepharose CL-6B chromatography (0.17 mM) [2].
• The fluorescence substrate kynuramine was used as a probe of the catalytic site of plasma amine oxidase [3].
• All mutant enzymes were expressed and exhibited lower specific activities as compared to WT MAO A using kynuramine as substrate [4].
• BP-N-methylbutylamine had a much higher affinity to MAO-A than an amine substrate, kynuramine, and it was a more potent inhibitor of MAO-A than of MAO-B [5].
• The Ki values of MAO-A and -B were determined to be 4.20 and 46.0 microM, respectively, while the Km values of MAO-A and -B with kynuramine were 44.1 and 90.0 microM, respectively [5].

Biological context of KYNURAMINE

• The method used kynuramine as a common substrate for both MAO-A and MAO-B in incubations, and the 4-hydroxyquinoline (4-HQ) resulting from deamination of kynuramine followed by intramolecular condensation was analyzed using LC/MS/MS; formation of 4-HQ was used as the marker of MAO activity to evaluate the effects of test compounds [6].
• Kynuramine increased heart rate and blood pressure in pithed rats [7].
• Unlike 5-OH-K, kynuramine, failed to evoke vasoconstriction and inhibited vascular responses to NE via alpha 1-adrenoceptors [8].
• Kynuramine: high affinity for [3H]tryptamine binding sites [9].
• TL-1 showed mixed-type inhibition of MAO in mouse liver when kynuramine was used as a substrate, and the IC50 was 6.6 microM [10].

Anatomical context of KYNURAMINE

• High concentrations of kynuramine (10(-4) M) produced modest inhibition and reduction in maximal responses to 5-HT in the jugular vein, aorta and guinea pig ileum.(ABSTRACT TRUNCATED AT 250 WORDS)[11]
• Using kynuramine as the substrate, cardiac MAO of rats was compared with that in the vas deferens and liver [12].
• The enzyme activities were measured in five brain regions, the frontal cortex, entorhinal cortex, hippocampus, hypothalamus and striatum, using kynuramine as the substrate [13].
• Similarly, kynuramine reversed clonidine-induced inhibition of the cholinergic twitch response in the guinea pig ileum [14].
• Mitochondrial monoamine oxidase (MAO) was found in human semen, showing its Km and Vmax values of 91.7 microM and 290 pmoles/mg of protein/60 min, respectively, with kynuramine as substrate [15].

Associations of KYNURAMINE with other chemical compounds

• Y444F MAO A oxidizes kynuramine with a k(cat) <2% of WT enzyme and is greater than 100-fold slower in catalyzing the oxidation of phenylethylamine or of serotonin [4].
• The properties of both enzymes with kynuramine as substrate, including Km values and pH optima at different kynuramine concentrations; the Rf values on polyacrylamide gel electrophoresis; and the thermal inactivation patterns were different [16].
• All platelet samples were investigated with 6 kynuramine concentrations as substrate (fluorometric assay) in the absence and presence of 200 mM ethanol (ETOH) in vitro [17].
• Localization of rat striatal monoamine oxidase activities towards dopamine, serotonin and kynuramine by gradient centrifugation and nigro-striatal lesions [18].
• The inhibitions of MAO in both brain and liver homogenate by RS-2232 in vitro measured with kynuramine (100 microM) were independent of the prolonged preincubation [19].

Gene context of KYNURAMINE

• Additionally, MAO A, isolated from human placenta, oxidizes MPTP to the same product at about 12% of the rate of kynuramine, again with a comparable Km value [20].
• The platelet MAO-B activity was determined fluorimetrically using kynuramine as a substrate [21].
• Coptisine competitively inhibited MAO-A activity with kynuramine [22].
• Coptisine showed an inhibitory effect on MAO-A activity in a concentration-dependent manner using a substrate kynuramine, but coptisine did not inhibit MAO-B activity [22].
• By kinetic analysis, MPP+ was found to inhibit MAO-A in competition with the substrate, kynuramine [23].

Analytical, diagnostic and therapeutic context of KYNURAMINE

• After sympathetectomy, various parts of the hearts and fractions of the hearts isolated by differential centrifugation were tested for changes in MAO activity with two different substrates (kynuramine and 14C-tryptamine) [24].
• METHODS: After platelet separation, PSL was determined fluorimetrically; PSU was measured by incubating aliquots of platelet-rich plasma with six concentrations of 14C-5-HT for 60 seconds at 37 degrees C, followed by vacuum filtration; platelet MAO-B activity (toward kynuramine as a substrate) was determined fluorimetrically [25].

References