Understanding Protein Structure: Primary to Quaternary Levels Explained

The shape of proteins. There are 4 different levels of protein structure, or protein shape. Primary, secondary, tertiary or the third level, and quaternary or the fourth level.

The primary or 1st level of protein structure is a chain like or linear sequence of amino acids joined by peptide bonds as you can see here. The secondary or 2nd level has 2 shapes, an alpha helix or

coil like formation, or a folded pattern called a beta sheet. In both of these structures hydrogen bonds between the R groups of the amino acids stabilize the shape of the protein.

The tertiary or 3rd level of protein structure involves more folding and bonding of the secondary structure. The coils may even touch each other as some covalent bonds form

from the sharing of electrons between different amino acids, but most of these twists and folds occur from the result of ionic bonds between positively and negatively charged R groups of the amino acids.

The quaternary or 4th level is where clusters of more than one polypeptide chain link together to form a giant molecule. Many different types of bonds may be formed within this structure.

The shape of a protein is important, for instance, fibrous proteins are extended linear proteins that are part of ligaments, tendons and muscles, and globular proteins fold into almost spherical shapes

and have their hydrophobic or water fearing R groups buried deep within the core, and their hydrophilic or water loving R groups extended out into the water when in an aqueous environment.

Proteins take their shape based on the job they are required to perform and some have moving parts that are important to their functions. Proteins can have their structure or shaped altered by denaturation.

When this happens, the protein is no longer able to carry out its job. Denaturation can take place because of change of temperature; change in pH, or the presence of certain hazardous chemicals.

And that, be the basics on the shape of proteins.