|Meat, fish, seafood, eggs, dairy products, dry beans and bean products are good sources of protein. Its major functions include building, repairing and maintaining healthy body tissues. That's why it's strongly advisable to take in plenty of proteins when we work out at gyms--proteins can repair broken muscle fibers and build new ones, making us stronger people.
Protein is nothing mysterious, it's just a very long, coiled chain of amino acids. Still, it's very fascinating, as each different sequence of amino acids can have distinct functions, which is why protein can perform so many tasks in our body.
Learn more about proteins: protein is so important, but why?
Protein exists in many forms in our body, and here lists a few and their functions:
Biological catalyst—enzymes. Enzymes have their special site for certain molecule to come in, known as active site. When the substrate comes into the active site, it’s activation energy will decrease a lot, and the chemical reaction turning the substrate into the product will happen much quicker. This is because that the special structure of enzyme chooses another pathway of the reaction. Without those enzymes, the rate of reaction inside our body will be too slow to maintain normal body functions.
Antibodies: “Do you think we are friendly with those enemies? No!” You must have heard of the word “antibody” especially during the covid-19 pandemic. Indeed, antibody is part of our immune system, and they response to pathogens by binding themselves with the pathogen, so that soldiers of greater power such as macrophage can identify the pathogen and kill it.
Hormones: almost all hormones in our body are proteins or protein derivatives. For example, the glucose-controlling hormone insulin: you can see that the insulin molecule is essentially two amino acid chains, with disulfide bonds (-S-S-) connecting each other. Together, their specific shape and way of connection between atoms will give them specific functions as hormones.
Transport proteins: Unlike most small, non-polar molecules, many larger and bulky molecules cannot directly pass through the cell membrane. Therefore, transport proteins are one of the carriers of those “special passengers”. They are usually much bigger than the phospholipid bilayer, which is the structure of cell membranes.
The structure of proteins:
You might have heard of another name of protein—polypeptide. Yes, this is the uncoiled structure of any protein molecule (you can see protein as just a long polypeptide chain coiled in a specific way to perform certain functions, and we call protein’s level of construction “tertiary structure”.) Polypeptides are many individual amino acids coming together.