biology

Xanthine dehydrogenase

Xanthine dehydrogenase is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Xanthine dehydrogenase rather than just read about it. In short: Xanthine dehydrogenase, also known as XDH, is a protein that, in humans, is encoded by the XDH gene. Function Xanthine dehydrogenase belongs to the group of molybdenum-containing hydroxylases involved in the oxidative metabolism of purines.

Key takeaways

Xanthine dehydrogenase belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Xanthine dehydrogenase to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Xanthine dehydrogenase from memory before moving on to harder problems.

Reference excerpt

Xanthine dehydrogenase, also known as XDH, is a protein that, in humans, is encoded by the XDH gene.

Function Xanthine dehydrogenase belongs to the group of molybdenum-containing hydroxylases involved in the oxidative metabolism of purines. The enzyme is a homodimer. Xanthine dehydrogenase can be converted to xanthine oxidase by reversible sulfhydryl oxidation or by irreversible proteolytic modification. Xanthine dehydrogenase catalyzes the following chemical reaction:

The three substrates of this enzyme are xanthine, NAD+, and H2O, whereas its three products are urate, NADH, and H+. This enzyme participates in purine metabolism.

Nomenclature This enzyme belongs to the family of oxidoreductases, to be specific, those acting on CH or CH2 groups with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is xanthine:NAD+ oxidoreductase. Other names in common use include NAD+-xanthine dehydrogenase, xanthine-NAD+ oxidoreductase, xanthine/NAD+ oxidoreductase, and xanthine oxidoreductase.

Clinical significance Defects in xanthine dehydrogenase cause xanthinuria, may contribute to adult respiratory stress syndrome, and may potentiate influenza infection through an oxygen metabolite-dependent mechanism. It has been shown that patients with lung adenocarcinoma tumors which have high levels of XDH gene expression have lower survivals. Addiction to XDH protein has been used to target NSCLC tumors and cell lines in a precision oncology manner.

See also Aldehyde oxidase and xanthine dehydrogenase, a/b hammerhead domain MOCOS Xanthine oxidase

References

Illustrations

Worked examples

Example 1 — a first encounter with Xanthine dehydrogenase

Start with the simplest possible case. Write down what Xanthine dehydrogenase claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Xanthine dehydrogenase before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Xanthine dehydrogenase ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Xanthine dehydrogenase

In research: Xanthine dehydrogenase appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Xanthine dehydrogenase in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Xanthine dehydrogenase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 1.17.1, EC 1.17.3, Enzymes of known structure, so understanding it makes those chapters shorter.
In everyday life: Look for Xanthine dehydrogenase outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Xanthine dehydrogenase in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Xanthine dehydrogenase means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Xanthine dehydrogenase out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Xanthine dehydrogenase in simple terms?

Xanthine dehydrogenase, also known as XDH, is a protein that, in humans, is encoded by the XDH gene. Function Xanthine dehydrogenase belongs to the group of molybdenum-containing hydroxylases involved in the oxidative metabolism of purines.

Why does Xanthine dehydrogenase matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Xanthine dehydrogenase?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Xanthine dehydrogenase.