Proteins are made of amino acids linked together by peptide bonds. Amino acids can be divided into essential amino acids and non – essential amino acids. Proteins and carbohydrates contain 4 kcal per gram.
Proteins are chemical compounds that contain the same atoms as carbohydrate and lipid – carbon (C), hydrogen (H) an oxygen (O) – but proteins are different in that they also contain nitrogen (N) atoms. These nitrogen atoms gives the name ‘amino’ (nitrogen containing) to the amino acids that are the links in the chains referred to as proteins.
Proteins are large molecules formed by the combination of a number of aminoacids. About 20 amino acids have been found to occur in proteins and are important from the point of view of human nutrition.
· Excellent sources of protein include tuna, shrimp, turkey, and cod.
· Very good sources of protein include snapper, venison, halibut, salmon, scallops, chicken, lamb, beef, calf ’s liver, spinach, tofu, mustard greens, mushrooms, soybeans, and mozzarella cheese.
· Good sources of protein include eggs, milk, collard greens, cauliflower and many legumes including lentils, split peas, kidney beans, black beans, pinto beans and garbanzo beans.
Production and maintenance of structural proteins
· Production of enzymes and hormones
· Production of transport proteins and lipoproteins
· Production of antibodies
· Maintenance of proper fluid balance
· Maintenance of proper acid – base balance.
Protein deficiency diseases – Maras muss and kwashiorkor