Summary
The overall three-dimensional shape of one polypeptide, held by side-chain interactions and disulfide bridges.
In depth
The polypeptide folds into a compact shape with hydrophobic residues buried and hydrophilic ones exposed. It is stabilised by hydrophobic interactions, hydrogen bonds, ionic bonds, van der Waals forces and covalent disulfide bridges.
The shape forms binding sites in enzymes and receptors. Domains are semi-independent folded regions.
Disulfide bridges, covalent links between two cysteines, are common in secreted proteins such as insulin and antibodies since the outside environment is oxidising. Domains are independent folding units, and many proteins combine several domains with different roles, which evolution reshuffles.
Techniques that reveal structure include X-ray crystallography, NMR spectroscopy and cryo-EM; the AI system AlphaFold now predicts shapes of most known proteins with high accuracy and was recognised by the 2024 Nobel Prize in Chemistry.
Frequently asked questions
What is Tertiary Structure?
The overall three-dimensional shape of one polypeptide, held by side-chain interactions and disulfide bridges.
Which area of biology covers Tertiary Structure, and how advanced is it?
Tertiary Structure is one of the 51 topics in Biomolecules & Biochemistry. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Quaternary Structure, Proteins, Carbon Chemistry.
Why does Tertiary Structure matter?
Drug design depends on the 3D shape of the target pocket.
Can you give an example of Tertiary Structure?
Myoglobin folds to hold a haem group that binds oxygen in muscle.
What should I learn before Tertiary Structure?
Work through the Beginner topics in Biomolecules & Biochemistry first, such as Water Properties, Carbon Chemistry, Carbohydrates, then return to Tertiary Structure. Intermediate topics assume the Beginner vocabulary.
What topics are related to Tertiary Structure?
The closest topics to Tertiary Structure are Quaternary Structure, Proteins, Carbon Chemistry, Amino Acids. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Tertiary Structure?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Tertiary Structure. To practise the whole of Biomolecules & Biochemistry, use the Biomolecules & Biochemistry quiz.
How is Tertiary Structure different from Quaternary Structure?
Tertiary Structure: The overall three-dimensional shape of one polypeptide, held by side-chain interactions and disulfide bridges. Quaternary Structure: The arrangement of multiple polypeptide subunits into one functional protein, such as haemoglobin. Read both side by side and note what each one explains.
How should I study Tertiary Structure step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Quaternary Structure and explain the difference aloud. Finally, take the Biomolecules & Biochemistry quiz and come back to this page for any question you miss.