BIOCHEMISTRY: PROTEINS Proteins Compounds composed of carbon, hydrogen, oxygen, and nitrogen which are arranged as strands of amino acids. Plays and essential role in the cellular maintenance, growth, and functioning of the human body. Makes up nearly 17% of the total body weight. Shapes of Protein Structure The 3-dimensional shape of proteins is derived from the sequence and properties of its amino acids and determines its function and interaction with other molecules. Amino acids are linked to the next by a peptide bond. Proteins of various lengths are made when amino acids are linked together. Dipeptide = 2 amino acids joined by a peptide bond. Tripeptide = 3 amino acids joined by a peptide bond. The unique shapes of protein enable them to perform their various tasks in the body. Denaturation happens when proteins uncoil or lose their shape impairing their ability to function. (Caused by: heat, acids, and other conditions) General Functions of Proteins Proteins acts as enzymes, hormones, and antibodies. They maintain fluid, acid, and base balance. They transport substances such as oxygen, vitamins, and minerals to target cells throughout the body. Structural Proteins (Keratin and Collagen) are responsible for the formation of bones, teeth, hair, and outer layer of skin. They also help maintain the structure of blood vessels and other tissues. Motor Proteins use energy and convert it into some form of mechanical work. Enzymes are proteins that facilitate chemical reactions without being changed in the process. Proenzyme = inactive form of an enzyme. Hormones are chemical messengers. These are proteins that travel to one or more specific target tissues or organs. Insulin = plays a key role in regulating the amount of glucose in the blood. Antibodies are giant protein molecules which combat invading antigens. Antigen = are usually foreign substances that have entered the body and could potentially be harmful. (virus and bacteria) Immunoproteins/Immunoglobins/Antibodies = defend the body from possible attacks by these invaders. Proteins help to maintain the body’s fluid and electrolyte balance. Three Fluid Compartments: Intracellular = inside the cell Extracellular = outside the cell Intravascular = in the blood The presence of blood protein molecules (albumins and globulins) are critical factors in maintaining the proper fluid balance between cells and extracellular space. Blood fluid is pulled into the capillary beds from the tissue through the mechanics of oncotic pressure. In which the pressure exerted by the protein molecules counteracts the blood pressure. Lack of blood proteins = clinical edema or tissue swelling. Proteins also help to maintain balance between acids and bases with body fluids. The body works hard to keep the pH of the blood near 7.4 (neutral). Food Sources Animal Sources Chicken, Fish, Eggs, Dairy products, Beef, and Pork Vegetarian Diet Dried beans, Peas, Soy, Nuts, and Seeds Whole Grains Rice and Legumes Classification of Proteins Simple proteins = hydrolysis yield amino acids and its derivatives. Albumin Egg albumin = Egg Serum albumin = Blood Lactaalbumin = Milk Globulin Serum globulin = Blood Lactogobulin = Egg Ovoglobulin = Egg yolk Legumin = Peas Edestin = Hemp Exelsin = Brazil nuts Glutenin Glutenins = Wheat Oryzenin = Corn Prolamines (Alcohol soluble proteins) Zein = Corn Gliadin = Wheat Histones Globulin = Hemoglobin Scrombrone = Mackerel Protamines Salmine = Salmon Sturine = Stugeron Fibrous protein/Albuminoids/Sclerins Collagen = Bones Cartilage Myosin = Muscle Keratin = Hair Fibrin = Blood Clots Conjugated proteins = hydrolysis amino acids and other type of compound (protein and nonprotein/prosthetics groups). Hemeproteins Myoglobins = found in hearth and skeletal muscle. Serves as a carrier of oxygen. Hemoglobin = RBC. Serves oxygen binder. Lipoproteins = serves as a lipid carrier LDL = Low Density Lipoprotein HDL = High Density Lipoprotein Glycoproteins Gamma globulin (immune gamma globulin) = antibody Mucin (saliva) = lubricant in mucous secretion. Interfernon = antiviral protection Osteomuccid = bones Tendomuccid = tendons Phosphoproteins Glycogen phosphorylase = enzyme in glycogen Casein = Milk Vitalin = Egg yolk Nucleoproteins Ribosomes = site for protein synthesis Viruses = self-reflection Matelloproteins/Chromoproteins Iron ferritin = storage complex for iron in liver and spleen. Hemoglobin = blood pigment Enzyme catalase, Peroxidase, and cytochrome C = iron containing enzymes. Hemocyanin = copper-protein complex. Derived proteins = proteins that are produced by the action of chemical enzymes. Primary Protein Derivatives or Hydrolysis Proteina = products of protein from the action of water and diluted acids. ­ Myosin ­ Odestan (Odestin) Metaproteins (infraproteins) = product of further action of acids and alkalies on proteins. ­ Acid albuminate ­ Alkali albuminate Coagulated Proteins = product from the action of heat or alcohol. Secondary Protein Derivatives or Extensive Hydrolysis Proteoses = Cannot be coagulated (hardened) by heating. Can be precipitated by ammonium sulfate. Peptones = Cannot be coagulated (hardened) by heating. Can be precipitated by ammonium sulfate and arsenophosphotungstic reagent (alkaloidal reagent). Peptides = combination of 2 or more amino acids. Optical activity = the ability to polarize light Acidity and Basicity Polarity and Non-polarity Hydrophilicity and Hydrophobicity There are 20 amino acids. There are 11 nonessential and 9 essential. Examples of Protein Derivatives Enzymes Contractile Muscle Hormones Neurotransmitters Storage Proteins Transport Proteins Amino Acids Are the fundamental building blocks of proteins. Consists elements such as: carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. Peptides are the long chains of amino acids. They make up the multicomponent, large complexes of protein. The arrangement of amino acids along the chain determines the structure and chemical properties of protein. General Structure: Carbon Center + 4 Substituents Amino group = NH2 Organic Acid (Carboxyl) Group = COOH Hydrogen Atom = H R-Group = that determines the structural identity and chemical properties of the amino acid. Basic Amino Acid Structure: R-CH(NH2)-COOH The biochemical properties of amino acids determine the role and function of protein in the human body. These categories offer clues to the function and reactivity of the amino acids in proteins. Non-essential (dispensable) Amino Acids. The body is able to adequately synthesize them. Provided that there are enough nitrogen, carbon, hydrogen, and oxygen available. Arginine Improved immune responses to bacteria, viruses, and tumor cells. Promotes wound healing and regeneration of liver. Causes the release of growth hormones. Crucial for optimal muscle growth and tissue repair. Tyrosine Transmits nerve impulse to the brain. Helps overcome depression. Improves memory. Increase mental awareness. Promotes the healthy functioning of the thyroid, adrenal, and pituitary glands. Glycine Helps trigger the release of oxygen to the energy-requiring cell making process. Important in the manufacturing of hormones responsible for strong immune system. Serine A storage source of glucose. Helps strengthen immune system by providing antibodies. Synthesize fatty acid sheath around the nerve fibers. Glutamic acid Considered to be nature’s brain food. Helps speed the healing of ulcers. Gives a “lift” from fatigue. Helps control alcoholism, schizophrenia, and the craving for sugar. Aspartic acid Aids in the expulsion of harmful ammonia from the body. May increase resistance to fatigue and increase endurance. Cystine Function as an oxidant and is powerful aid to the body in protecting against radiation and pollution. It can help slowdown aging process, deactivate free radicals, and neutralize toxins. Aids in protein synthesis and present cellular change. Necessary for the formation of skin, which aids in recovery from burns and surgical operations. Hair and skin are made up of 10-14% of cystine. Proline Extremely important for the proper functioning of joints and tendons. Helps maintain and strengthen heart muscle. Alanine Important source of energy for muscle tissue, brain, and central nervous system. Strengthens the immune system by producing antibodies. Helps in the metabolism of sugar and organic acids. Taurine Helps stabilize the excitability of membrane, important for epileptic seizures. Together with sulfur, they are necessary for the control of many biochemical changes that takes place in aging process. Aids in the clearing of free radical wastes. *Not part of the “non-essential” amino acids in the table. However, because it is one of the few amino acids not used in protein synthesis, taurine is often referred to as a “nonessential” amino acid, or more generously as a “conditionally essential” amino acid.* Essential (indispensable) Amino Acids. The body is unable to adequately synthesize them. These are supplied through diet. Tryptophan A natural relaxant help alleviate insomnia by inducing normal sleep. Reduces anxiety and depression. Help in the treatment of migraine. Helps the immune system. Helps reduce the risk of artery and heart spasms. Works with lysine in reducing cholesterol levels. Lysine Insure the adequate absorption of calcium. Helps form collagen. Aids in the production of antibodies, hormones, and enzymes. Maybe effective against herpes. Methionine Principle supplier of sulfur. Helps lower cholesterol levels by increasing the liver’s production of lecithin. Reduces liver fat and protects the kidneys. A natural chelating agent for heavy metals. Regulate the formation of ammonia and creates ammonia-free urine which reduces bladder irritation. Influences hair follicles and promotes hair growth. Phenylalanine Used by the brain to produce norepinephrine – a chemical that transmits signals between nerve cells and the brain. Keeps you awake and alert Reduces hunger pains Functions as an antidepressant and helps improve memory. Threonine Important constituent of collagen, elastin, and enamel proteins. Helps prevent fat build-up in the liver Helps the digestive and intestinal tracts function more smoothly Assist metabolism and assimilation Valine Promotes mental vigor, muscle coordination, and calm emotions. Leucine and Isoleucine Provide ingredient for the manufacturing of other essential biochemical components in the body. Are utilized for the production of energy. Stimulates upper brain helping us to be more alert. Histidine Is found abundantly in hemoglobin. Has been used in the treatment of rheumatoid arthritis, allergic disease, ulcer, and anemia. Antibodies Antibodies are our molecular watchdogs waiting and watching for viruses, bacteria, and other unwanted visitors. They circulate in the blood. With viruses (rhinovirus and poliovirus), a coating of bound antibodies may be enough to block infections. With bacteria, they are no match to them. They just act as a marker alerting the other powerful defensive mechanism available in the immune system. Blood contains 100,000,000 different types of antibodies. Are created by recombination of genes in the lymphocytes – blood cells that make antibodies. Ig A = the immunoglobin responsible for protecting the body surface. Ig D = found very small amount and is thought to be involved in the regulation of antibody synthesis. Ig M = first antibody produced in response to infection. Ig G = the major serum immunoglobin. Ig E = responsible for allergies and for the overblown allergies. Lipoproteins HDL (High Density Lipoproteins) = Cholesterol for healthy individual. Normal HDL for Women = 55mg/100mL of blood. Normal HDL for Men = 45mg/100mL of blood. LDL (Low Density Lipoproteins) = Bad Cholesterol. It increases cholesterol content in the circulatory system. VLDL (Very Low Density Lipoproteins) = Present in less healthy individual.
