1 Protein And Amino Acids

2 The Roles Of Protein Building materials Enzymes Hormones Regulators of fluid and electrolyte balance Acid-base regulators Transporters Antibodies

3 As Building Materials Proteins serve as the building blocks of most body structures. Bone and teeth contain a protein matrix. Protein collagen is the material of ligaments and tendons.

4 As Enzymes Enzymes are proteins that facilitate chemical reactions without being changed in the process; Protein catalyst.

5 As Hormones Some hormones are proteins. Growth hormone Insulin and glucagon Thyroxin. Calcitonin and parathyroid Antidiuretic hormone

6 As Regulators Of Fluid And Electrolytes Balance The body’s fluids are contained inside the blood vessels (intravascular), within the cells (intracellular), and between the cells (intercellular). Fluids flow freely between these compartments. Cells can’t move these fluids, instead they manufacture proteins. Proteins help regulate the composition of body fluids, as well as their quantity. They maintain equilibrium in the surrounding fluids by moving molecules into and out of cells.

7 As Acid-Base Regulators Acids- compounds that release hydrogen ions. Bases- compounds that accept hydrogen ions. Buffers- compounds that help keep a solution’s acidity or alkalinity constant. Normal body processes continually produce acids and bases, which the blood carries to the kidneys and lungs for excretion. Proteins act as buffers, maintaining the acid-base balance of the blood and body fluids.

8 As Transporters Proteins function as carriers for: Vitamins Minerals Lipids Oxygen

9 As Antibodies Proteins protect the body against disease. Antibodies are giant protein molecules produced by the immune system designed to combat “foreign invaders”. They combine with and inactivate the foreign invader thus protecting the body.

10 Proteins And Amino Acids Proteins- compounds composed of carbon, hydrogen, oxygen, and nitrogen atoms, arranged from amino acids linked in chains. Amino acids- building blocks of proteins: Each contain an amino group (NH 2 ), an acid group (COOH), a hydrogen atom (H), and a distinctive side group all attached to a central carbon atom (C).

11 Amino Acids There are 20 common amino acids which proteins are comprised of. 9 of them are essential, the remaining 11 are not. * Note: essential means that the human body cannot make them. We must obtain them from our diet.

12 Essential Versus Non- Essential Essential Histidine Lysine Methionine Phenylalanine Threonine Tryptophan Leucine Isoleucine Valine Non-essential Alanine Arginine Asparagine Aspartic acid Cysteine Glutamic acid Glutamine Glycine Proline Serine Tyrosine

13 Proteins Peptide bonds are the bonds that link amino acids together to form protein. Dipeptide- two amino acids bonded together. Tripeptide- three amino acids bonded together. Polypeptide- many amino acids bonded together. Condensation reactions create the bonds between amino acids.

14 Digestion Of Proteins In the stomach- Hydrochloric acid Denatures the protein structure Converts pepsinogen to pepsin Pepsin Cleaves proteins to smaller polypeptides and free amino acids

15 Digestion Of Proteins {continued} In the small intestines- Enteropeptidase Converts pancreatic trypsinogen to trypsin

16 Digestion Of Proteins {continued} Trypsin Cleaves peptide bonds for specific amino acids Converts pancreatic procarboxypepitases to carboxypeptidases Converts pancreatic chymotrypsinogen to chymotrypsin

17 Digestion Of Proteins {continued} Chymotrypsin Cleaves peptide bonds for specific amino acids Carboxypeptidases Cleave amino acids from the acid end of polypeptides Elastase and collagenase Cleaves polypeptides into smaller polypeptides into smaller polypeptides and tripeptides

18 Digestion Of Proteins {continued} Aminopeptidase Cleaves amino acids from the amino ends of small polypeptides Tripeptidase Cleaves tripeptides into dipeptides and amino acids

19 Absorption Of Amino Acids Free amino acids and some di- and tripeptides which escaped digestion enter the bloodstream from the intestinal cells.

20 Protein Quality Can determine how well children grow and how well adults maintain health Limiting amino acid- the essential amino acid found in the shortest supply relative to the amounts needed for protein synthesis in the body. The four most likely to be limiting: lysine, methionine, threonine, and tryptophan.

21 Protein Quality {continued) Complete protein- a dietary protein that contains all the essential amino acids in relatively the same amounts that human beings require. Complementary proteins- two or more incomplete proteins whose amino acid assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other.

22 Proteins In Foods Meat, fish, poultry, and dairy products are the richest sources of protein. Legumes and grain products contain moderate amounts of protein. Vegetables and fruit provide little protein.

23 Recommended Amounts Of Proteins Protein should account for ~ 15% of total daily energy intake. The RDA for adults is 0.8 grams per kilogram of body weight.

24 Protein-Energy Malnutrition- PEM PEM is a deficiency of both protein and energy. It is the world’s most widespread malnutrition problem, including kwashiorkor, marasmus, and a combination of both.

25 Kwashiorkor A form of PEM that results either from in- adequate protein intake or infections, however, with adequate calories. Usually acute in nature. Due to the lack of protein and subsequently, fluid maintenance, faces and limbs become swollen with edema. They develop fatty livers which account for the swollen belly appearance.

26 Marasmus A form of PEM that results from a chronic deficiency of calories, or impaired absorption, of energy, vitamins, and minerals. This is characterized by extreme loss of muscle and fat, wasted appearance.