Protein Surprisingly little is known about protein and health but some recommendations Adults need 0.8 grams of protein/kg of body weight per day to keep from slowly breaking down their own tissues Just over 7 grams of protein are needed for every 20 pounds of body weight
Protein There's relatively little solid information on the ideal amount of protein in the diet a healthy target for calories contributed by protein the best kinds of protein.
Too Little Protein? the conditions known as Kwashiorkor and Maramus. growth failure loss of muscle mass decreased immunity weakening of the heart and respiratory system You die
Too Much Protein? Digesting it releases acids that the body usually neutralizes with calcium and other buffering agents in the blood. Eating lots of protein, such as the amounts recommended in the so-called low-carb or no-carb diets, removes lots of calcium from the body. Some of this may be pulled from bone.
What is Protein? Take away the water and about 75 percent of body weight is protein Muscle, bone, skin, hair, and virtually every other body part or tissue. (25% of muscle) Enzymes that power many chemical reactions and the hemoglobin that carries oxygen At least 10,000 different proteins make the body what it is.
What is Protein? Twenty or so basic building blocks, called amino acids, provide the raw material for all proteins. Following genetic instructions, the body strings together amino acids. Some genes call for short chains, others are blueprints for long chains that fold, origami-like, into intricate, three-dimensional structures.
What is Protein? Because the body doesn't store amino acids, as it does fats or carbohydrates, it needs a daily supply of amino acids to make new protein. It does not need a supply of dietary amino acids to make ALL the protein the body synthesizes in a day Protein the body no longer requires is broken down to its component amino acids and they may be used to synthesis another body protein
Amino Acids Side group Side group differences is how the twenty amino acids are different . O H N C C H OH H Amine Group Acid Group
The Chemist’s View of Proteins • Amino Acids • The unique side groups result in differences in the size, shape and electrical charge of an amino acid
The Chemist’s View of Proteins • Amino Acids • Nonessential amino acids, also called dispensable amino acids, are ones the body can create.
The Chemist’s View of Proteins • Amino Acids • Essential amino acids, also called indispensable amino acids, must be supplied by the foods people consume. • Essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenyalanine, threonine, tryptophan, and valine. • Conditionally essential amino acids refer to amino acids that are normally nonessential but essential under certain conditions.
The Chemist’s View of Proteins • Proteins • Amino acid chains are linked by peptide bonds in condensation reactions. • Dipeptides have two amino acids bonded together. • Tripeptides have three amino acids bonded together. • Polypeptides have more than two amino acids bonded together.
Peptide Bonding O H O H H H N C C N C C H OH H OH Side group 1 water Side group 2 Amino Acid 1 Amino Acid 2
Amino Acid Sequence • Protein is made by bonding amino acids in a specific sequence • . • Each amino acid must be but in the order specified by the genetic code responsible for synthesizing the protein • If an (essential) amino acid is unavailable, protein synthesis is limited
Amino Acid Sequence Amino acid 1 Amino acid 2
Amino Acid Sequence Amino acid3 3 Amino acid 1 Amino acid 2
Amino Acid Sequence Amino acid 3 Amino acid 1 Amino acid 4 Amino acid 2
Amino Acid Sequence Amino acid3 3 Amino acid 1 Amino acid 4 Amino acid 2 Amino acid 5 Amino acid 7 Amino acid 9 Amino acid 6 Amino acid 8 Amino acid 10 Amino acid 11 Amino acid 12 Amino acid 13 ETC>
Proteins in the Body • Protein Synthesis • Synthesis is unique for each human being and is determined by the amino acid sequence. • Delivering the instructions through messenger RNA (genetic material) • Carries a code to the nuclear membrane • Presents a list to make a strand of protein • Transfer RNA lines up the amino acids and brings them to the messenger
Proteins in the Body • Proteins are versatile and unique. The synthesis of protein is determined by genetic information. • Protein is constantly being broken down and synthesized in the body. • Researchers measure nitrogen balance to study synthesis, degradation and excretion of protein.
Proteins in the Body • Protein has many important functions in the body. • Protein can be used for energy if needed; (gluconeogenesis) and its excesses are stored as FAT. • The study of proteins is called proteomics.
Proteins in the Body • Roles of Proteins • Building Materials for Growth and Maintenance = LIFE • A matrix of collagen is filled with minerals to provide strength to bones and teeth. • Replaces tissues including the skin, hair, nails, and GI tract lining
Proteins in the Body • Roles of Proteins • Enzymes are proteins that facilitate anabolic (building up) and catabolic (breaking down) chemical reactions.
Proteins in the Body • Roles of Proteins • Hormones regulate body processes and some hormones are proteins. • An example is insulin.
Proteins in the Body • Roles of Proteins • Regulators of Fluid Balance • Plasma proteins attract water • Maintain the volume of body fluids to prevent edema which is excessive fluid • Maintain the composition of body fluids
Proteins in the Body • Roles of Proteins • Acid-Base Regulators • Act as buffers by keeping solutions acidic or alkaline • Acids are compounds that release hydrogen ions in a solution. • Bases are compounds that accept hydrogen ions in a solution. • Acidosis is high levels of acid in the blood and body fluids. • Alkalosis is high levels of alkalinity in the blood and body fluids.
Proteins in the Body • Roles of Proteins • Transporters • Carry lipids, vitamins, minerals and oxygen in the body • Act as pumps in cell membranes, transferring compounds from one side of the cell membrane to the other
Proteins in the Body • Roles of Proteins • Antibodies • are large proteins that are found in blood or other bodily fluids of vertebrates • Fight bacteria and viruses, also known as antigens, that invade the body • Provide immunity to fight an antigen more quickly the second time exposure occurs
Proteins in the Body • Roles of Proteins • Source of energy and glucose if needed • Other Roles • Blood clotting by producing fibrin which forms a solid clot • Vision by creating light-sensitive pigments in the retina
Proteins in the Body • A Preview of Protein Metabolism • Protein Turnover and the Amino Acid Pool • Protein turnover is the continual making and breaking down of protein. • Amino acid pool is the supply of amino acids that are available. • Amino acids from food are called exogenous. • Amino acids from within the body are called endogenous.
Amino Acid Pool Cellular Proteins Dietary Proteins Amino Acid Pool Cellular Proteins Amino Acids ENERGY NH3
Proteins in the Body • A Preview of Protein Metabolism • Nitrogen Balance • Zero nitrogen balance is nitrogen equilibrium, when input equals output. • Positive nitrogen balance means nitrogen consumed is greater than nitrogen excreted. • Negative nitrogen balance means nitrogen excreted is greater than nitrogen consumed.
Proteins in the Body • A Preview of Protein Metabolism • Using Amino Acids to Make Proteins or Nonessential Amino Acids – Cells can assemble amino acids into the protein needed. • Using Amino Acids to Make Other Compounds • Neurotransmitters are made from the amino acid tyrosine. • Tyrosine can be made into the melanin pigment or thyroxine. • Tryptophan makes niacin and serotonin.
Proteins in the Body • A Preview of Protein Metabolism • Using Amino Acids for Energy and Glucose • There is no readily available storage form of protein. • Breaks down tissue protein for energy if needed glucose Body Protein Dietary Protein Amino Acids
Proteins in the Body • Proteins are versatile and unique. The synthesis of protein is determined by genetic information. • Protein is constantly being broken down and synthesized in the body. • Researchers measure nitrogen balance to study synthesis, degradation and excretion of protein. • Protein has many important functions in the body. • Protein can be used for energy if needed; its excesses are stored as fat. • The study of proteins is called proteomics.
Proteins in the Body • A Preview of Protein Metabolism • Deaminating Amino Acids • Nitrogen-containing amino groups are removed. • Ammonia is released into the bloodstream. • Ammonia is converted into urea by the liver. • Kidneys filter urea out of the blood. • Using Amino Acids to Make Fat • Excess protein is deaminated and converted into fat. • Nitrogen is excreted.
Proteins in the Body • A Preview of Protein Metabolism • Deaminating Amino Acids O H H • Nitrogen-containing amino groups are removed. • Ammonia is released into • the bloodstream. • Ammonia is converted into • urea by the liver. • Kidneys filter urea out of • the blood. N C C H OH Side group
Proteins in the Body • A Preview of Protein Metabolism Using Amino Acids to Make Fat • Excess protein is deaminated and converted into fat. • Nitrogen is excreted. FAT Body Protein Dietary Protein Amino Acids Ammonia Ammonia
Dietary Protein Complete protein contains all the essential amino acids needed to build new proteins. Animal sources of protein tend to be complete Incomplete proteins sources lack one or more essential amino acids that the body can't make from scratch or create by modifying another amino acid These usually come from fruits, vegetables, grains, and nuts.
Protein in Foods • Eating foods of high-quality protein is the best assurance to get all the essential amino acids. • Complementary proteins can also supply all the essential amino acids. • A diet inadequate in any of the essential amino acids limits protein synthesis. • The quality of protein is measured by its amino acid content, digestibility, and ability to support growth.
Protein in Foods • Protein Quality • Digestibility • Depends on protein’s food source • Animal proteins are 90-99% absorbed. • Plant proteins are 70-90% absorbed. • Soy and legumes are 90% absorbed. • Other foods consumed at the same time can change the digestibility
Protein in Foods • Protein Quality • Amino Acid Composition • The liver can produce nonessential amino acids. • Cells must dismantle to produce essential amino acids if they are not provided in the diet. • Limiting amino acids are those essential amino acids that are supplied in less than the amount needed to support protein synthesis. • Reference Protein is the standard by which other proteins are measured. (Egg White) • Based on their needs for growth and development, preschool children are used to establish this standard.
Protein in Foods • Protein Quality • High-Quality Proteins • Contains all the essential amino acids • Animal foods contain all the essential amino acids. • Plant foods are diverse in content and tend to be missing one or more essential amino acids. • Complementary Proteins • Combining plant foods that together contain all the essential amino acids • Used by vegetarians
Protein in Foods • Protein Quality • A Measure of Protein Quality - PDCAAS (protein digestibility-corrected amino acid score) • Compares amino acid composition of a protein to human amino acid requirements • Adjusts for digestibility
Protein in Foods • Protein Regulation for Food Labels • List protein quantity in grams • % Daily Values is not required but reflects quantity and quality of protein using PDCAAS.
Health Effects and Recommended Intakes of Protein • Protein deficiency and excesses can be harmful to health. • Protein deficiencies arise from protein-deficient diets and energy-deficient diets. • This is a worldwide malnutrition problem, especially for young children. • High-protein diets have been implicated in several chronic diseases.