Protein Structure Tutorials
A protein needs to adopt a final and stable 3-dimensional shape in order to function properly. The Tertiary Structure of a protein is the arrangement of the secondary structures into this final 3-dimensional shape.
The sequence of amino acids in a protein (the primary structure) will determine where alpha helices and beta sheets (the secondary structures) will occure. These secondary structure motifs then fold into an overall arrangement that is the final 3-dimensional fold of the protein (the tertiary structure).Each unique sequence of amino acids gives rise to a unique protein type, with a unique shape and function.
A summary of primary, secondary and tertiary structure is shown below.
Most proteins fold into their tertiary structure in an aqueous environment - a cell is, after all, 60% water. The chemical properties of the various R-groups (sidechains) of the amino acids within the protein chain will influence the way that the protein folds in its environment.
When a protein is surrounded by water:
Click the buttons below to see each of these four groupings of amino acid types shown in the insulin protein in the display to the right. Click Here to download a chart summarizing all 20 amino acids and their R-group shapes.
Positive and Negative
Proteins are amazing molecules because they come in a huge variety of sizes and shapes; each shape suited to perform a specific task. The primary sequence of amino acids in a protein determines its 3-dimensional shape which, in turn, determines how the protein will function. This structure-function relationship is key to appreciating proteins and protein structure.
The same sequence of amino acids in an amino acid chain will fold into the same 3-dimensional shape each time it is made, allowing the body to produce millions of identical copies of any particular type of protein. This pattern is due to the properties of its unique sequence of amino acids (primary structure). As long as the sequence of amino acids is the same, the protein will fold into the same 3-dimensional shape.
If a protein does not fold correctly it will not function properly. Therefore, researching a protein's structure is very important when trying to understand what it does and how it works.
When scientists study a protein they must first determine the sequence of amino acids in the protein chain (primary structure). They use this sequence to predict the presence of any alpha helices or beta sheets (secondary structure). They can then use X-ray crystallography and NMR to determine a protein's full 3-dimensional shape (tertiary structure). Knowing the tertiary structure of a protein is often crucial to understanding how it functions and how to target it for drug therapy or other medical uses.
© Copyright 1995- - MSOE Center for BioMolecular Modeling