Product Name:	Human Xanthine dehydrogenase/oxidase (XDH) ELISA Kit
Product Code:	HUEB0843
Alias:	Xanthine dehydrogenase/oxidase, XDH, XDHA
Uniprot:	P47989
Reactivity:	Human
Range:	0.156-10 ng/mL
Detection Method:	Sandwich
Size:	96 Assay
Storage:	Please see kit components below for exact storage details
Note:	For research use only

UniProt Protein Function:	XDH: Key enzyme in purine degradation. Catalyzes the oxidation of hypoxanthine to xanthine. Catalyzes the oxidation of xanthine to uric acid. Contributes to the generation of reactive oxygen species. Has also low oxidase activity towards aldehydes (in vitro). Defects in XDH are the cause of xanthinuria type 1 (XU1). Xanthinuria is characterized by excretion of very large amounts of xanthine in the urine and a tendency to form xanthine stones. Uric acid is strikingly diminished in serum and urine. XU1 is due to isolated xanthine dehydrogenase. XU1 patients can metabolize allopurinol. Belongs to the xanthine dehydrogenase family.
UniProt Protein Details:	Protein type:EC 1.17.1.4; Secondary Metabolites Metabolism - caffeine; Xenobiotic Metabolism - drug metabolism - other enzymes; Nucleotide Metabolism - purine; EC 1.17.3.2; Oxidoreductase Chromosomal Location of Human Ortholog: 2p23.1 Cellular Component: cytosol; extracellular space Molecular Function:2 iron, 2 sulfur cluster binding; FAD binding; molybdopterin cofactor binding; oxidoreductase activity, acting on the aldehyde or oxo group of donors; protein homodimerization activity; xanthine dehydrogenase activity; xanthine oxidase activity Biological Process: caspase activation; negative regulation of endothelial cell differentiation; negative regulation of endothelial cell proliferation; negative regulation of protein amino acid phosphorylation; negative regulation of protein kinase B signaling cascade; purine nucleotide catabolic process; xanthine catabolic process Disease: Xanthinuria, Type I
NCBI Summary:	Xanthine dehydrogenase belongs to the group of molybdenum-containing hydroxylases involved in the oxidative metabolism of purines. The encoded protein has been identified as a moonlighting protein based on its ability to perform mechanistically distinct functions. Xanthine dehydrogenase can be converted to xanthine oxidase by reversible sulfhydryl oxidation or by irreversible proteolytic modification. Defects in xanthine dehydrogenase cause xanthinuria, may contribute to adult respiratory stress syndrome, and may potentiate influenza infection through an oxygen metabolite-dependent mechanism. [provided by RefSeq, Jan 2014]
UniProt Code:	P47989
NCBI GenInfo Identifier:	2506326
NCBI Gene ID:	7498
NCBI Accession:	P47989.4
UniProt Secondary Accession:	P47989,Q16681, Q16712, Q4PJ16,
UniProt Related Accession:	P47989
Molecular Weight:	146,424 Da
NCBI Full Name:	Xanthine dehydrogenase/oxidase
NCBI Synonym Full Names:	xanthine dehydrogenase
NCBI Official Symbol:	XDH
NCBI Official Synonym Symbols:	XO; XOR
NCBI Protein Information:	xanthine dehydrogenase/oxidase
UniProt Protein Name:	Xanthine dehydrogenase/oxidase
UniProt Synonym Protein Names:	Xanthine oxidoreductase; XOR
Protein Family:	Xanthine dehydrogenase
UniProt Gene Name:	XDH
UniProt Entry Name:	XDH_HUMAN

Component	Quantity (96 Assays)	Storage
ELISA Microplate (Dismountable)	8×12 strips	-20°C
Lyophilized Standard	2	-20°C
Sample Diluent	20ml	-20°C
Assay Diluent A	10mL	-20°C
Assay Diluent B	10mL	-20°C
Detection Reagent A	120µL	-20°C
Detection Reagent B	120µL	-20°C
Wash Buffer	30mL	4°C
Substrate	10mL	4°C
Stop Solution	10mL	4°C
Plate Sealer	5	-

Other materials and equipment required:

Microplate reader with 450 nm wavelength filter
Multichannel Pipette, Pipette, microcentrifuge tubes and disposable pipette tips
Incubator
Deionized or distilled water
Absorbent paper
Buffer resevoir

*Note: The below protocol is a sample protocol. Protocols are specific to each batch/lot. For the correct instructions please follow the protocol included in your kit.

Allow all reagents to reach room temperature (Please do not dissolve the reagents at 37°C directly). All the reagents should be mixed thoroughly by gently swirling before pipetting. Avoid foaming. Keep appropriate numbers of strips for 1 experiment and remove extra strips from microtiter plate. Removed strips should be resealed and stored at -20°C until the kits expiry date. Prepare all reagents, working standards and samples as directed in the previous sections. Please predict the concentration before assaying. If values for these are not within the range of the standard curve, users must determine the optimal sample dilutions for their experiments. We recommend running all samples in duplicate.

Step
1.	Add Sample: Add 100µL of Standard, Blank, or Sample per well. The blank well is added with Sample diluent. Solutions are added to the bottom of micro ELISA plate well, avoid inside wall touching and foaming as possible. Mix it gently. Cover the plate with sealer we provided. Incubate for 120 minutes at 37°C.
2.	Remove the liquid from each well, don't wash. Add 100µL of Detection Reagent A working solution to each well. Cover with the Plate sealer. Gently tap the plate to ensure thorough mixing. Incubate for 1 hour at 37°C. Note: if Detection Reagent A appears cloudy warm to room temperature until solution is uniform.
3.	Aspirate each well and wash, repeating the process three times. Wash by filling each well with Wash Buffer (approximately 400µL) (a squirt bottle, multi-channel pipette,manifold dispenser or automated washer are needed). Complete removal of liquid at each step is essential. After the last wash, completely remove remaining Wash Buffer by aspirating or decanting. Invert the plate and pat it against thick clean absorbent paper.
4.	Add 100µL of Detection Reagent B working solution to each well. Cover with the Plate sealer. Incubate for 60 minutes at 37°C.
5.	Repeat the wash process for five times as conducted in step 3.
6.	Add 90µL of Substrate Solution to each well. Cover with a new Plate sealer and incubate for 10-20 minutes at 37°C. Protect the plate from light. The reaction time can be shortened or extended according to the actual color change, but this should not exceed more than 30 minutes. When apparent gradient appears in standard wells, user should terminatethe reaction.
7.	Add 50µL of Stop Solution to each well. If color change does not appear uniform, gently tap the plate to ensure thorough mixing.
8.	Determine the optical density (OD value) of each well at once, using a micro-plate reader set to 450 nm. User should open the micro-plate reader in advance, preheat the instrument, and set the testing parameters.
9.	After experiment, store all reagents according to the specified storage temperature respectively until their expiry.

When carrying out an ELISA assay it is important to prepare your samples in order to achieve the best possible results. Below we have a list of procedures for the preparation of samples for different sample types.

Sample Type	Protocol
Serum	If using serum separator tubes, allow samples to clot for 30 minutes at room temperature. Centrifuge for 10 minutes at 1,000x g. Collect the serum fraction and assay promptly or aliquot and store the samples at -80°C. Avoid multiple freeze-thaw cycles. If serum separator tubes are not being used, allow samples to clot overnight at 2-8°C. Centrifuge for 10 minutes at 1,000x g. Remove serum and assay promptly or aliquot and store the samples at -80°C. Avoid multiple freeze-thaw cycles.
Plasma	Collect plasma using EDTA or heparin as an anticoagulant. Centrifuge samples at 4°C for 15 mins at 1000 × g within 30 mins of collection. Collect the plasma fraction and assay promptly or aliquot and store the samples at -80°C. Avoid multiple freeze-thaw cycles. Note: Over haemolysed samples are not suitable for use with this kit.
Urine & Cerebrospinal Fluid	Collect the urine (mid-stream) in a sterile container, centrifuge for 20 mins at 2000-3000 rpm. Remove supernatant and assay immediately. If any precipitation is detected, repeat the centrifugation step. A similar protocol can be used for cerebrospinal fluid.
Cell culture supernatant	Collect the cell culture media by pipette, followed by centrifugation at 4°C for 20 mins at 1500 rpm. Collect the clear supernatant and assay immediately.
Cell lysates	Solubilize cells in lysis buffer and allow to sit on ice for 30 minutes. Centrifuge tubes at 14,000 x g for 5 minutes to remove insoluble material. Aliquot the supernatant into a new tube and discard the remaining whole cell extract. Quantify total protein concentration using a total protein assay. Assay immediately or aliquot and store at ≤ -20 °C.
Tissue homogenates	The preparation of tissue homogenates will vary depending upon tissue type. Rinse tissue with 1X PBS to remove excess blood & homogenize in 20ml of 1X PBS (including protease inhibitors) and store overnight at ≤ -20°C. Two freeze-thaw cycles are required to break the cell membranes. To further disrupt the cell membranes you can sonicate the samples. Centrifuge homogenates for 5 mins at 5000xg. Remove the supernatant and assay immediately or aliquot and store at -20°C or -80°C.
Tissue lysates	Rinse tissue with PBS, cut into 1-2 mm pieces, and homogenize with a tissue homogenizer in PBS. Add an equal volume of RIPA buffer containing protease inhibitors and lyse tissues at room temperature for 30 minutes with gentle agitation. Centrifuge to remove debris. Quantify total protein concentration using a total protein assay. Assay immediately or aliquot and store at ≤ -20 °C.
Breast Milk	Collect milk samples and centrifuge at 10,000 x g for 60 min at 4°C. Aliquot the supernatant and assay. For long term use, store samples at -80°C. Minimize freeze/thaw cycles.