ENZYMATIC METHOD FOR THE EVALUATION OF XYLOSE

• Main Authors: MONSALVE HERNANDO, Carmen, GARCÍA JUNCEDA, Eduardo, SÁNCHEZ MORENO, Israel, FERNÁNDEZ MAYORALAS, Alfonso, MARTÍN MARTÍN, José Luis, HERMIDA DIAZ, Carmen
• Format: Patent
• Language: English; French; German
• Published: 31.10.2018
• Subjects: BEER; BIOCHEMISTRY; CHEMISTRY; COMPOSITIONS OR TEST PAPERS THEREFOR; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL ORENZYMOLOGICAL PROCESSES; ENZYMOLOGY; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEICACIDS OR MICROORGANISMS; METALLURGY; MICROBIOLOGY; MUTATION OR GENETIC ENGINEERING; PHYSICS; PROCESSES OF PREPARING SUCH COMPOSITIONS; SPIRITS; TESTING; VINEGAR; WINE

The invention provides an alternative sensitive and specific method for D-xylose quantification that could replace the colorimetric method without compromising detection accuracy, using xylose dehydrogenase, particularly XylB from Caulobacter crescentus NA-1000, as the only enzyme in the assay kit. This enzymatic method can be used to quantify D-xylose in urine and/or blood samples after performing a test to diagnose hypolactasia. This test is non-invasive and involves the ingestion of the disaccharide 4-O-beta-galactopyranosyl-D-xylose (4-GX or Gaxilose). This disaccharide is hydrolysed by intestinal lactase, producing D-xylose, which is absorbed into the blood and excreted in urine. D-Xylose levels in urine and blood are proportional to the quantity of intestinal lactase. Thus, the test provides an evaluation of the global intestinal lactase activity in the whole individual and it is not based on measuring the metabolic consequences derived from its deficiency. It does not require specialised equipment, does not cause apparent discomfort in patients with lactase deficiency and is very reliable, thus overcoming the drawbacks of the diagnostic tests currently in use. Moreover, the enzymatic method for D-xylose detection of invention is statistically significantly better than the xylose quantification colorimetric methods in terms of its reliability. This could allow the diagnostic test to become the reference or gold standard test for the indication of hypolactasia diagnosis.