biology

Transaminase

Transaminase 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 Transaminase rather than just read about it. In short: Transaminases or aminotransferases are enzymes that catalyze a transamination reaction between an amino acid and an α-keto acid. They are important in the synthesis of amino acids, which form proteins.

Key takeaways

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

Reference excerpt

Transaminases or aminotransferases are enzymes that catalyze a transamination reaction between an amino acid and an α-keto acid. They are important in the synthesis of amino acids, which form proteins. Two important transaminase enzymes, aspartate transaminase (AST), and alanine transaminase (ALT), are commonly used as indicators of liver and cardiac health.

Function and mechanism An amino acid contains an amino (NH2) group. A keto acid contains a keto (=O) group. In transamination, the NH2 group on one molecule is exchanged with the =O group on the other molecule. The amino acid becomes a keto acid, and the keto acid becomes an amino acid. Transaminases require the coenzyme pyridoxal phosphate, which is converted into pyridoxamine in the first half-reaction, when an amino acid is converted into a keto acid. Enzyme-bound pyridoxamine in turn reacts with pyruvate, oxaloacetate, or alpha-ketoglutarate, giving alanine, aspartic acid, or glutamic acid, respectively. Many transamination reactions occur in tissues, catalysed by transaminases specific for a particular amino/keto acid pair. The reactions are readily reversible, the direction being determined by which of the reactants are in excess. This reversibility can be exploited for synthetic chemistry applications to achieve the synthesis of valuable chiral amines. The specific enzymes are named from one of the reactant pairs, for example; the reaction between glutamic acid and pyruvic acid to make alpha ketoglutaric acid and alanine is called alanine transaminase and was originally called glutamic-pyruvic transaminase or GPT for short.

Tissue transaminase activities can be investigated by incubating a homogenate with various amino/keto acid pairs. Transamination is demonstrated if the corresponding new amino acid and keto acid are formed, as revealed by paper chromatography. Reversibility is demonstrated by using the complementary keto/amino acid pair as starting reactants. After chromatogram has been taken out of the solvent the chromatogram is then treated with ninhydrin to locate the spots.

Amino acid metabolism in animals Animals must metabolize proteins to amino acids, at the expense of muscle tissue, when blood sugar is low. The preference of liver transaminases for oxaloacetate or alpha-ketoglutarate plays a key role in funneling nitrogen from amino acid metabolism to aspartate and glutamate for conversion to urea for excretion of nitrogen. In similar manner, in muscles the use of pyruvate for transamination gives alanine, which is carried by the bloodstream to the liver (the overall reaction being termed glucose-alanine cycle). Here other transaminases regenerate pyruvate, which provides a valuable precursor for gluconeogenesis. This alanine cycle is analogous to the Cori cycle, which allows anaerobic metabolism by muscles.

Diagnostic uses The transaminase enzymes are important in the production of various amino acids, and measuring the concentrations of various transaminases in the blood is important in the diagnosing and tracking many diseases. For example, the presence of elevated transaminases can be an indicator of liver and cardiac damage. Two important transaminase enzymes are aspartate transaminase (AST), also known as serum glutamic oxaloacetic transaminase (SGOT); and alanine transaminase (ALT), also called alanine aminotransferase (ALAT) or serum glutamate-pyruvate transaminase (SGPT). These transaminases were discovered in 1954 and their clinical importance was described in 1955.

See also Valproic acid - a GABA transaminase inhibitor

References

Illustrations

Worked examples

Example 1 — a first encounter with Transaminase

Start with the simplest possible case. Write down what Transaminase 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 Transaminase 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 Transaminase 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 Transaminase

In research: Transaminase 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 Transaminase 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: Transaminase is common in secondary-school and first-year university syllabi. It links to neighbouring topics EC 2.6.1, Hepatology, Protein metabolism, so understanding it makes those chapters shorter.
In everyday life: Look for Transaminase 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 Transaminase in 20 minutes

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

Frequently asked questions

What is Transaminase in simple terms?

Why does Transaminase 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 Transaminase?

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 Transaminase.