»Apotheken Umschau«, published November 2008

Amino acids (proteins): structure and functions of an extremely versatile group of substances

All the proteins in our bodies are made up of individual amino acids. Amino acids are thus the building blocks of protein. Some background information first: all the proteins in our bodies are made up of individual amino acids. Amino acids are thus the building blocks of protein.

Proteins are very important. After all, they make up around 50 percent of our dry body weight and thus participate in nearly every metabolic process in our body. A protein is made up of different sequences of building blocks, namely, amino acids. These form extremely complex structures. A protein comprising only 100 building blocks – and which is thus comparatively small – can have 10¹³² theoretical variants. This is many times more possible combinations than there are atoms in the universe.

Every protein is a high-precision tool and the shape must be 100% correct, for even one wrong building block may stop it working. This can result in a serious illness such as sickle-cell disease. Not only the sequence of the individual units is important, for external factors such as temperature, must also be right for the protein to take up the correct three-dimensional structure. If these parameters go beyond certain limiting values, the protein loses its shape and functionality. This comes into play when we have a fever for instance. The higher temperature has a negative effect on the pathogen's metabolic proteins.

What proteins do in the body

• They are the basic components of muscles, ligaments, skin and connective tissue.
• They confer shape and structure to the cells e.g. in skin and bones.
• As enzymes, they speed up or enable certain metabolic processes.
• They regulate the transport of substances in and out of the cells.
• As receptors, they pass on messages from hormones from the outside of the cell into the interior.
• They are an important part of the immune system.
• They transport oxygen in the blood.

Take insulin as an example: how a protein is assembled

Like all proteins, amino acids represent the basic building blocks of this hormone, which regulates the blood sugar level. There are 20 different amino acids. In the first step, they are linked to form a chain. The correct sequence is specified by the genetic material, which is nothing less than the building instructions for insulin – and for all the other proteins in the body.

Just like a lock and key, the insulin molecule fits exactly onto the protrusion on its counterpart, the insulin receptor (which is also a protein). This docking triggers a series of reactions in the cell that lead to uptake of glucose from the blood into the cell interior.