biology

L-xylulose reductase

L-xylulose reductase 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 L-xylulose reductase rather than just read about it. In short: Dicarbonyl/L-xylulose reductase, also known as carbonyl reductase II, is an enzyme that in human is encoded by the DCXR gene located on chromosome 17. Structure The DCXR gene encodes a membrane protein that is approximately 34 kDa in size and composed of 224 amino acids.

Key takeaways

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

Reference excerpt

Dicarbonyl/L-xylulose reductase, also known as carbonyl reductase II, is an enzyme that in human is encoded by the DCXR gene located on chromosome 17.

Structure The DCXR gene encodes a membrane protein that is approximately 34 kDa in size and composed of 224 amino acids. The protein is highly expressed in the kidney and localizes to the cytoplasmic membrane.

Function DCSR catalyzes the reduction of several L-xylylose as well as a number of pentoses, tetroses, trioses, alpha-dicarbonyl compounds. The enzyme is involved in carbohydrate metabolism, glucose metabolism, the uronate cycle and may play a role in the water absorption and cellular osmoregulation in the proximal renal tubules by producing xylitol. In enzymology, L-xylulose reductase (EC 1.1.1.10) is an enzyme that catalyzes the chemical reaction

Its two substrates are xylitol and the oxidised cofactor nicotinamide adenine dinucleotide phosphate (NADP+). The products are L-xylulose, reduced NADPH, and a proton. This enzyme belongs to the superfamily of short-chain oxidoreductases, specifically those acting on the CH-OH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is xylitol:NADP+ 2-oxidoreductase (L-xylulose-forming).

Clinical significance A deficiency is responsible for pentosuria. The insufficiency of L-xylulose reductase activity causes an inborn error of metabolism disease characterized by excessive urinary excretion of L-xylulose. Over-expression and ectopic expression of the protein may be associated with prostate adenocarcinoma.

Illustrations

Worked examples

Example 1 — a first encounter with L-xylulose reductase

Start with the simplest possible case. Write down what L-xylulose reductase 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 L-xylulose reductase 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 L-xylulose reductase 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 L-xylulose reductase

In research: L-xylulose reductase 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 L-xylulose reductase 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: L-xylulose reductase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 1.1.1, EC 1.1.1 stubs, Enzymes of known structure, so understanding it makes those chapters shorter.
In everyday life: Look for L-xylulose reductase 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 L-xylulose reductase in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what L-xylulose reductase 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 L-xylulose reductase out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is L-xylulose reductase in simple terms?

Dicarbonyl/L-xylulose reductase, also known as carbonyl reductase II, is an enzyme that in human is encoded by the DCXR gene located on chromosome 17. Structure The DCXR gene encodes a membrane protein that is approximately 34 kDa in size and composed of 224 amino acids.

Why does L-xylulose reductase 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 L-xylulose reductase?

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 L-xylulose reductase.