Chemistry

Proteins and the genetic code


The folding of a protein

The sequence of the individual amino acids, i.e. the primary structure, is not the only relevant factor for the function of a protein. Every protein is folded in a very specific way, and it is only in this way that it can fulfill its function in the cell. At the molecular level, this means that charged amino acids in the protein come into contact with other, oppositely charged amino acids or that in certain areas of the protein, e.g. hydrophobic amino acids, form an anhydrous space. These anhydrous protein areas are mostly located inside the protein and are often involved in enzyme reactions.

When a protein is folded, regular folding patterns, the secondary structures, can arise, which can look like a spiral (α-helix) or a folded sheet (β-sheet). These secondary structures play an important role in the properties of proteins: predominantly helical proteins are firm structures with varying degrees of flexibility (horn, fingernails, collagen), while proteins consisting mainly of β-sheet components are soft and flexible (silk).

For this purpose, covalent bonds can be formed between cysteine ​​side chains, which stabilize the folding of the protein as a whole (tertiary structure), or several polypeptide chains are joined together by non-covalent bonds to form a large protein (quaternary structure).

If this natural fold is destroyed, the protein is denatured and no longer active. Cooking, frying or baking are everyday processes in which the quaternary, tertiary and secondary structure of a protein is irretrievably dissolved without the amino acid sequence itself changing. In other processes, only the tertiary structure is dissolved, while the secondary structure remains intact - e.g. in the case of permanent waves.

Would you like to know more about the folding of proteins and the four levels of protein structure? Link to the learning material "The structure of proteins"


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