At the beginning structure, Primary Structure, proteins look like just strings.
At the second stage, Secondary Structure, they start folding, and coiling, forming two types of protein ingredients. One abundant part of proteins is called the Alpha Helix. Alpha Helices are common in proteins. They look like a spiral.. The other part is the Beta Sheet or Beta Pleated Sheet. They are large, thick arrows that represent the direction of where the chain is facing. One of the enzymes containing many Beta Sheets is the HIV-1 Protease.
At the third stage, Tertiary Structure, there are interactions with the unfolded parts of the protein/enzyme.
Quaternary Structures are many Tertiary Structures combined into one chain. An example of this is also Hemoglobin, made up of 4 subunits.
Proteins can be folded wrong if they fold prematurely by themselves. A hypothesis suggests that wrongly folded proteins may result in prions, a very dangerous type of protein. Therefore, a larger protein complex called a chaperonin assist with the folding. It is not known how chaperonin proteins achieve this, but correctly folded proteins are essential.