Proteins are very important molecules in our cells. They are involved in virtually all cell functions. Each protein within the body has a specific role. Some proteins are involved in structural support, while others are involved in bodily movement, or in defense against germs.
Proteins vary in structure as well as function. They are constructed from a set of 20 amino acids and have distinct three-dimensional shapes. Below is a list of a few types of proteins and their functions:
Antibodies defend the body from germs. Contractile proteins are responsible for movement. Enzymes speed up chemical reactions. Storage proteins store amino acids.
Proteins do more in your body than just help build strong muscles. They are present in every cell and tissue, each one with a highly specialized function necessary for normal development and function with no one role more important than the others. You obtain most of the protein your body uses through your diet, but your body can make proteins as well.
Structure Proteins can consist of a single chain of less than 100 amino acids up to a complex structure of several chains with hundreds of folds and a three-dimensional shape. These larger proteins, called structural proteins, provide structure and shape to cells, organs and connective tissue.
Muscle Contraction Actin and myosin are two specialized types of filament protein present in your muscle. When stimulated by a signal from the central nervous system, these two proteins act in unison to shorten in length, causing your muscle to contract.
Immunity Antibodies, another protein, help your body fight infection. For each antigen that enters your body, you have a separate and distinct antibody to fight it. Antibodies immobilize and sequester antigens until white blood cells can destroy them.
Enzymes Your body performs thousands of biochemical reactions a day to function properly. These reactions require energy, and many have significantly high energy thresholds that can delay essential reactions. Proteins called enzymes assist in lowering the activation energy of hundreds of reactions, helping them to proceed thousands of times faster than they would in a normal environment. A well-known example of an enzyme is lactase, which facilitates the metabolism of lactose, or milk sugar, in your small intestine to aid in digestion.
Hormones Hormones are proteins that send signals and coordinate activities throughout the body. Examples include insulin, which facilitates glucose metabolism and controls blood glucose levels; thyroid hormones, which regulate metabolism, body temperature and the synthesis of other proteins; and gonadotropins, which stimulate the production of sperm and ova.
Transport Transport proteins carry other proteins and compounds throughout the body. Hemoglobin is a type of transport protein present in red blood cells; it carries oxygen from the lungs to all tissues and cells and transports carbon dioxide, a metabolic waste product, back to the lungs for excretion from the body.
Energy Your body can use protein for its energy needs when carbohydrates are depleted. When needed, proteins degrade into their component amino acids, which are then oxidized in the same process as glucose to create energy. However, prolonged use of protein for energy can cause problems if not enough protein remains to perform its essential functions, according to “Human Physiology.”
Protein can be found in a wide range of food:
Beef Hamburger patty, 4 oz – 28 grams protein Steak, 6 oz – 42 grams Most cuts of beef – 7 grams of protein per ounce
Chicken Chicken breast, 3.5 oz - 30 grams protein Chicken thigh – 10 grams (for average size) Drumstick – 11 gramsWing – 6 grams Chicken meat, cooked, 4 oz – 35 grams
Fish Most fish fillets or steaks are about 22 grams of protein for 3 ½ oz (100 grams) of cooked fish, or 6 grams per ounce Tuna, 6 oz can - 40 grams of protein
Pork Pork chop, average - 22 grams protein Pork loin or tenderloin, 4 oz – 29 grams Ham, 3 oz serving – 19 grams Ground pork, 1 oz raw – 5 grams; 3 oz cooked – 22 grams Bacon, 1 slice – 3 grams Canadian-style bacon (back bacon), slice – 5 – 6 grams
Eggs and Dairy Egg, large - 6 grams protein Milk, 1 cup - 8 grams Cottage cheese, ½ cup - 15 grams Yogurt, 1 cup – usually 8-12 grams, check labelSoft cheeses (Mozzarella, Brie, Camembert) – 6 grams per oz Medium cheeses (Cheddar, Swiss) – 7 or 8 grams per oz Hard cheeses (Parmesan) – 10 grams per oz
Beans (including soy) Tofu, ½ cup 20 grams protein Tofu, 1 oz, 2.3 grams Soy milk, 1 cup - 6 -10 grams Most beans (black, pinto, lentils, etc) about 7-10 grams protein per half cup of cooked beans Soy beans, ½ cup cooked – 14 grams protein Split peas, ½ cup cooked – 8 grams
Nuts and Seeds Peanut butter, 2 Tablespoons - 8 grams protein Almonds, ¼ cup – 8 grams Peanuts, ¼ cup – 9 grams Cashews, ¼ cup – 5 grams Pecans, ¼ cup – 2.5 grams Sunflower seeds, ¼ cup – 6 grams Pumpkin seeds, ¼ cup – 8 grams Flax seeds – ¼ cup – 8 grams