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Glycoside hydrolase family 19

Glycoside hydrolase family 19 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 Glycoside hydrolase family 19 rather than just read about it. In short: In molecular biology, Glycoside hydrolase family 19 is a family of glycoside hydrolases EC 3.2.1., which are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families.

Glycoside hydrolase family 19 — main illustration
Glycoside hydrolase family 19 — illustration

Key takeaways

  • Glycoside hydrolase family 19 belongs to biology; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Glycoside hydrolase family 19 to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Glycoside hydrolase family 19 from memory before moving on to harder problems.

Reference excerpt

In molecular biology, Glycoside hydrolase family 19 is a family of glycoside hydrolases EC 3.2.1., which are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families. This classification is available on the CAZy web site, and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes. y[ _]9 Glycoside hydrolase family 19 CAZY GH_19 comprises enzymes with only one known activity; chitinase (EC 3.2.1.14). Chitinases are enzymes that catalyze the hydrolysis of the beta-1,4-N-acetyl-D-glucosamine linkages in chitin polymers. Chitinases belong to glycoside hydrolase families 18 or 19. Chitinases of family 19 (also known as classes IA or I and IB or II) are enzymes from plants that function in the defence against fungal and insect pathogens by destroying their chitin-containing cell wall. Class IA/I and IB/II enzymes differ in the presence (IA/I) or absence (IB/II) of a N-terminal chitin-binding domain. The catalytic domain of these enzymes consist of about 220 to 230 amino acid residues.

Active site

GH19 enzymes has a conserved sequence motif ([FHY]-G-R-G-[AP]-ζ-Q-[IL]-[ST]-[FHYW]-[HN]-[FY]-[NY], ζ= hydrophilic amino acid) in its active site.

References

Illustrations

Glycoside hydrolase family 19 illustration
Glycoside hydrolase family 19: Active site of gycoside hydrolase family 19 papaya chitinase (PDB: 3cql​).[10] Conserved residues are shown surrounding the catalytic acid, Glu67. A GlcNAc2 unit binding in the -1 and +1 subsites is shown in narrow stick representation and an arrow indicates the position of the glycosidic oxygen.
Active site of gycoside hydrolase family 19 papaya chitinase (PDB: 3cql​).[10] Conserved residues are shown surrounding the catalytic acid, Glu67. A GlcNAc2 unit binding in the -1 and +1 subsites is shown in narrow stick representation and an arrow indicates the position of the glycosidic oxygen.

Worked examples

Example 1 — a first encounter with Glycoside hydrolase family 19

Start with the simplest possible case. Write down what Glycoside hydrolase family 19 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 Glycoside hydrolase family 19 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 Glycoside hydrolase family 19 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 Glycoside hydrolase family 19

In research
Glycoside hydrolase family 19 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 Glycoside hydrolase family 19 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
Glycoside hydrolase family 19 is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 3.2.1, Glycoside hydrolase families, Protein families, so understanding it makes those chapters shorter.
In everyday life
Look for Glycoside hydrolase family 19 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 Glycoside hydrolase family 19 in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Glycoside hydrolase family 19 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 Glycoside hydrolase family 19 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Glycoside hydrolase family 19 in simple terms?

In molecular biology, Glycoside hydrolase family 19 is a family of glycoside hydrolases EC 3.2.1., which are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glyco…

Why does Glycoside hydrolase family 19 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 Glycoside hydrolase family 19?

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 Glycoside hydrolase family 19.

Tags

  • EC 3.2.1
  • Glycoside hydrolase families
  • Protein families

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