Secondary, Tertiary and Higher Order Protein Structure
Protein structure can be characterized into different levels:
- Primary Order Structure – The sequence of amino acids in the polypeptide chain held together by peptide bonds. The primary sequence of a protein is unique to that protein, and defines the structure and function of the protein.
- Secondary Order Structure – Localized structures that form based on interactions within the protein backbone. The most common types of secondary structures are the α helix and the β pleated sheet. Both structures are held in shape by hydrogen bonds, which form between the carbonyl and amino group of the peptide bond.
- Tertiary Order Structure – The three-dimensional (3D) shape of a protein. Interactions of the amino acid side chains within a particular protein determine its tertiary structure.
- Quaternary Order Structure – The structure of a multi-protein complex such as dimer, trimer and more complex multi-protein subunit systems.
Secondary, tertiary and quaternary structure is often collectively termed as the higher order structure (HOS) of a protein. HOS is responsible for the correct folding and three-dimensional shape of a biopharmaceutical. This can be affected by different formulations, which in turn can affect protein activity. The folding and shape of the protein impacts directly on the functionality of the drug and this correlation is often termed as the “structure function relationship”.
Incorrect higher order structure can also raise safety concerns. If the overall folding and therefore 3D shape of a protein is wrong, receptor binding can be inhibited, immunogenic epitopes can be exposed and aggregation can occur. It is therefore crucial to employ a thorough characterization of the higher order structure of the protein. Biophysical characterization methods should be performed alongside functional analyses and primary structure characterization to allow a full understanding of the overall protein structure.
BioPharmaSpec offers a comprehensive range of biophysical techniques to fully characterize the higher order structure and stability of your protein.
Let us characterize the higher order structure of your molecule of interest
There is a comprehensive range of methods available at BioPharmaSpec to assess the higher order structure of your biopharmaceutical. Contact us today to request a proposal for the most appropriate and informative techniques for your product.