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Holocarboxylase synthetase

Holocarboxylase synthetase 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 Holocarboxylase synthetase rather than just read about it. In short: Holocarboxylase synthetase (biotin—(propionyl-Coenzyme A-carboxylase (ATP-hydrolysing)) ligase)), also known as protein—biotin ligase, is a family of enzymes (EC 6.3.4.10). This enzyme is important for the effective use of biotin, a B vitamin found in foods such as liver, egg yolks, and milk.

Key takeaways

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

Reference excerpt

Holocarboxylase synthetase (biotin—(propionyl-Coenzyme A-carboxylase (ATP-hydrolysing)) ligase)), also known as protein—biotin ligase, is a family of enzymes (EC 6.3.4.10). This enzyme is important for the effective use of biotin, a B vitamin found in foods such as liver, egg yolks, and milk. In many of the body's tissues, holocarboxylase synthetase activates other specific enzymes (called biotin-dependent carboxylases) by attaching biotin to them. These carboxylases are involved in many critical cellular functions, including the production and breakdown of proteins, fats, and carbohydrates. The catalyzed reaction:

ATP + biotin + apo-propionyl-CoA:carbon-dioxide ligase (ADP-forming) ⇌ {\displaystyle \rightleftharpoons } AMP + diphosphate + propionyl-CoA:carbon-dioxide ligase (ADP-forming) The 3 substrates of this enzyme are ATP, biotin, and [[apo-[propionyl-CoA:carbon-dioxide ligase (ADP-forming)]], whereas its 3 products are AMP, diphosphate, and propionyl-CoA:carbon-dioxide ligase (ADP-forming). Holocarboxylase synthetase may also play a role in regulating the activity of genes. In the nucleus, the enzyme likely attaches biotin molecules to histones, which are structural proteins that bind to DNA and give chromosomes their shape. Changing the shape of histones may help determine whether certain genes are turned on or off; however, it is not known how adding biotin affects gene regulation. The HLCS gene is located on the long (q) arm of chromosome 21 at position 22.1, from base pair 37,045,059 to base pair 37,284,372.

Related conditions Holocarboxylase synthetase deficiency: About 30 mutations in the HLCS gene have been identified in people with holocarboxylase synthetase deficiency. Most of these mutations substitute one amino acid (a building block of proteins) for another amino acid in the holocarboxylase synthetase enzyme. Many of the known mutations occur in a region of the enzyme that binds to biotin. These mutations reduce the enzyme's ability to attach biotin to carboxylases and histones. Without biotin, carboxylases remain inactive and are unable to process proteins, fats, and carbohydrates. A lack of holocarboxylase synthetase activity may also alter the regulation of certain genes that are important for normal development. Researchers believe that these disruptions in important cellular functions lead to breathing problems, skin rashes, and the other characteristic signs and symptoms of holocarboxylase synthetase deficiency.

See also Biotinylation

References Siegel L, Foote JL, Coon MJ (March 1965). "The enzymatic synthesis of propionyl coenzyme A holocarboxylase from d-biotinyl 5'-adenylate and the apocarboxylase". The Journal of Biological Chemistry. 240 (3): 1025–31. doi:10.1016/S0021-9258(18)97532-0. PMID 14284697.

External links holocarboxylase+synthetases at the U.S. National Library of Medicine Medical Subject Headings (MeSH)

Worked examples

Example 1 — a first encounter with Holocarboxylase synthetase

Start with the simplest possible case. Write down what Holocarboxylase synthetase 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 Holocarboxylase synthetase 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 Holocarboxylase synthetase 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 Holocarboxylase synthetase

In research
Holocarboxylase synthetase 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 Holocarboxylase synthetase 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
Holocarboxylase synthetase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 6.3.4, Enzymes of unknown structure, Genes on human chromosome 21, so understanding it makes those chapters shorter.
In everyday life
Look for Holocarboxylase synthetase 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 Holocarboxylase synthetase in 20 minutes

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

Frequently asked questions

What is Holocarboxylase synthetase in simple terms?

Holocarboxylase synthetase (biotin—(propionyl-Coenzyme A-carboxylase (ATP-hydrolysing)) ligase)), also known as protein—biotin ligase, is a family of enzymes (EC 6.3.4.10). This enzyme is important for the effective use of biotin, a B vitamin found in foods such as liver, egg yolks, and milk.

Why does Holocarboxylase synthetase 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 Holocarboxylase synthetase?

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 Holocarboxylase synthetase.

Tags

  • EC 6.3.4
  • Enzymes of unknown structure
  • Genes on human chromosome 21
  • Human genes
  • Ligase stubs

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