Protein is the second most abundant substance in your body, next to water, according to the University of Arkansas Division of Agriculture. It is found in every part of your body, from your hair and nails to your muscles, bones and organs. It is important to eat dietary protein to maintain the levels of proteins in your body. Without this multifunctional nutrient, you could not survive.
Protein Functions
Proteins perform more functions than any other nutrient. Proteins allow your body to build most enzymes and hormones. In fact, many hormones are proteins, according to “Nutrition and You” by Joan Salge Blake. Some proteins, called transport proteins, carry substances like oxygen, lipids, sodium and potassium, through your blood and into and out of cells. Proteins also help maintain acid-base balance and fluid balance and allow your immune system to function properly.
Protein and Calories
Protein belongs to a group of nutrients called macronutrients for two reasons – it contains calories and your body needs the nutrient in large amounts. Each gram of protein contains 4 calories per gram. Because of this, protein is able to provide you with energy, if need be. It is not ideal to rely on protein as an energy source, however, because this prevents it from performing its other functions.
Protein is also a macronutrient because your body needs large amounts of the nutrient to function properly. For every kilogram, or 2.2 pounds of body weight, you should consume 0.8 grams of protein.
Protein Components
Every protein is made up of building blocks called amino acids. The amino acid sequence, or the order in which amino acids come together, determines the type of protein that is made. Although sources differ on the exact amount of amino acids that exist, the general consensus is that there is a total of 20. Of these 20 amino acids, approximately half are nonessential, which means that your body can make them so it is not necessary to obtain them through your diet. The remaining half are essential, which means that your body can’t make them so you have to meet your needs through your diet. Proteins that contain all of the essential amino acids are classified as complete proteins. Proteins that lack adequate amounts of one or more of the essential amino acids are classified as incomplete proteins.
Protein Structure
The structure of protein, which is normally clustered or folded, can be denatured, or unfolded, with exposure to heat, acids, bases or salts. Denaturation does not change the amino acid sequence, but it changes the shape of the protein, which changes its function permanently.
Cooks rely on denaturation to improve the taste and texture of protein-rich foods. Cooking an egg denatures the protein to produce a better-tasting egg. Marinating a steak with salt helps denature the proteins to make the steak more tender.
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