PROTEIN

• Each protein folds into a unique three-dimensional structure defined by its amino acid sequence.
• Proteins are key players in our living systems.
• Proteins are polymers consisting of 20 kinds of amino acids.
• Protein can be obtained from plant and animal sources.
• Proteins are complex organic molecules made up of carbon, hydrogen, oxygen and nitrogen.
• Proteins differ from carbohydrates and fats because of the presence of nitrogen.
• Proteins are composed of α-amino acids linked together by peptide linkages.
• The name protein is derived from the Greek word proteios, which means “primary or first and are necessary for life,” as proteins are the basis of the cytoplasm of cells and are present in all living organisms.
• Proteins are the most abundant macromolecules in living cells and constitute 50% or more of their dry weight.
• Amino acids are the building units of proteins.
• The central carbon (α carbon) of an amino acid is where the amino group, carboxyl group (acid), and R group (side chain) are located.
• There are 20 different amino acids that create different combinations for specific functions in the body.
• DNA provides the instructions for how the amino acids will be linked to form the proteins in your body.
• The R group determines the amino acid.
• Abbreviation for the 20 amino acids.
• Nonessential amino acids, also known as dispensable amino acids, can be made within the body.
• Essential amino acids, also known as indispensable amino acids, must be obtained from foods.
• Conditionally essential amino acids are needed from food sources if the building blocks to make them are not available.
• Protein structure consists of monomer (amino acids), polymer (polypeptide), and large and complex molecules.
• Supportive proteins, such as keratin, collagen, and silk, are used in structures like hair, nails, and cocoons.
• Motor proteins, such as actin and myosin, make up muscle fibers and allow cell components to move from place to place.
• Quaternary (4°) structure is the arrangement of two or more tertiary folded peptide subunits bonded together to make a functional protein.
• Animal sources of protein, such as beef, pork, lamb, poultry, and fish, are the largest source of protein.
• Protein denaturation happens when a protein changes its shape, usually uncoiling, which changes its function and properties.
• Defensive proteins, such as antibodies, are produced by the immune system to combat bacteria and viruses and bind to unwanted substances to eliminate them.
• Examples of protein denaturation include an egg being mostly liquid until cooked and milk becoming yogurt or cheese when acids or enzymes are added.
• Hemoglobin and collagen are examples of proteins with quaternary (4°) structure.
• Plant sources of protein can be found in grains, nuts, seeds, and legumes.
• Regulatory proteins, such as hormones, are intercellular messengers that influence metabolism.
• Tempeh, a meat analogue, is made from soybeans and is a good source of protein, fiber, and iron.
• Transport proteins, such as hemoglobin and channel and carrier proteins in the cell membrane, allow substances to enter and exit the cell.
• Factors that cause protein denaturation include heat, acids, bases, alcohol.
• Meat is an excellent source of protein but can be high in fat and lack fiber.
• The primary structure of a protein is the order of amino acids in the chain, determined by gene (DNA), and a slight change in amino acid sequence can affect the protein’s structure and function.
• The secondary structure of a protein is “local folding,” which involves folding along short sections of polypeptide and involves interaction between adjacent amino acids.
• The tertiary structure of a protein is “whole molecule folding,” which is created when the secondary structure fold and form bonds to stabilize the structure into a unique shape, determined by interactions between R groups.
• Hardness, gumminess and chewiness are found to be exponentially correlated with egg albumen content, pH and their interaction.
• Egg albumen has a marked effect on the physico-chemical properties of analogue meat products but fat levels were least influenced by the variation in incorporation of egg albumen in the products.
• Egg albumen increases brown background color and gel like appearance on increasing temperature and pH.
• Soy protein is a good source of calcium and linoleic acid.