Minerals Biochemistry Lecture Notes PDF

COURSE TITLE :BIOCHEMISTRY I COURSE CODE :FM 104 DEPARTMENT :BIOCHEMISTRY Lecture Title: Minerals Lecturer Name: Ass. Prof. Dr. Omnia Safwat El-Deeb  LECTURE OBJECTIVES: Each student at this lecture should be able to: Know the biochemical classification of Mi...

COURSE TITLE :BIOCHEMISTRY I COURSE CODE :FM 104 DEPARTMENT :BIOCHEMISTRY Lecture Title: Minerals Lecturer Name: Ass. Prof. Dr. Omnia Safwat El-Deeb  LECTURE OBJECTIVES: Each student at this lecture should be able to: Know the biochemical classification of Minerals Recognize the functions of important Minerals. Identify the signs of clinical deficiency and over production of important minerals and mechanism of thier absorption. CONTENTS: Classification of minerals Calcium (Functions & deficiency) Phosphorus (Functions) Iron (Absorption, Functions & deficiency) Zinc (important enzymes require calcium) Fluoride and tooth decay  MINERALS *Definition: - They are inorganic compounds that are essential for the normal growth and maintenance of the body. *Classification: A-Macrominerals (Bulk elements): O They are required in amounts greater than 100 mg/day. B-Microminerals (Trace elements): O They are required in amounts less than 100 mg/day. CLASSIFICATION OF MINERALS : I-CALCIUM  I-Sources: Milk and milk products are considered as the richest sources. II. Daily requirements: - An adult needs 500 mg per day and a child about 1200 mg/ day. - Requirement may be increased to 1500 mg/day during pregnancy and lactation. - After the age of 50, there is a general tendency for osteoporosis, which may be prevented by increased calcium plus vitamin D. III. Absorption & Excretion : - Absorption is taking place from the first and second part of duodenum. - Calcium is absorbed against a concentration gradient and requires energy. - Absorption requires a carrier protein, helped by calcium-dependent ATPase. - Out of the 500 mg of calcium, 400 mg is excreted in stool and 100 mg is excreted through urine IV-Distribution of body calcium: Calcium is the most abundant mineral in the body (about 1200 grams). -99% of calcium: is present in bones and teeth. - 1 % of calcium: is present in body fluids and other tissues. V. Plasma calcium: 1 Plasma calcium level ranges from: 9 - 11 mg / dl. 2 Forms: Plasma calcium is present in 2 forms: a. Diffusible Calcium: It forms 50% of total serum calcium & is present in ionized form (essential for blood clotting). b. Non-diffusible Calcium: Is present in combination with albumin & Can`t cross the cell membrane  CALCIUM AND ENZYMES ACTIVITY 1- Calmodulin is a calcium binding regulatory protein. 2- It can bind with 4 calcium ions. 3- Calcium binding leads to activation of enzymes. 4- Calmodulin is part of various regulatory kinases. - Some other enzymes are activated directly by Ca without the intervention of calmodulin; examples are - Pancreatic lipase; - Enzymes of coagulation pathway; - Rennin (milk clotting enzyme in stomach)  2-PHOSPHOROUS I-Source: 1- Milk and milk products. 2- Fish, meat, liver and kidney and Leafy vegetables and egg yolk. Phospho-protein of diet such as casein of milk and vetillin of eggs. II-Daily requirements: - Adults: 800-1000mg/d - Pregnant women: 1500- 2000mg/d III-Absorption: 1- Phosphorus (in the form of phosphate) is absorbed by an active transport mechanism. 2-Phosphorus helps filter out waste in the kidneys and plays an essential role in how the body stores and uses energy IV. Distribution in the body: -Total body phosphorus is about 700 gm, most of them (600 gm) is present in the skeleton (bones and teeth). V.Plasma phosphorous: Normal plasma inorganic phosphorus: 3-5 mg/dl. N.B. - Phosphorus holds an inverse relationship with calcium. - An excess of serum calcium or phosphate results in the excretion of the other by the kidney - Normally Ca/P ratio must be constant. - Ca x P in 50. (If plasma phosphate increases (as in renal failure) the plasma, calcium decreases to keep the ratio constant) V-Function of phosphorous: 1- Formation of bones. 2-Plasma buffers (phosphate buffers). 3- Cellular components: a -Nucleic acids: DNA, RNAs. b- Phospholipids: e.g. lecithin, cephalin. c- Phosphoproteins: e.g.: casein of milk. d- Coenzymes: e.g. NAD, NADP. e- Second messengers: Cyclic AMP f- High energy phosphate compounds e.g. ATP, GTP, creatine and phosphate. 3-SODIUM & POTASSIUM  I-IRON One of the most important trace elements I-Sources: - Meat, liver, kidney, some plant sources ( nuts, beans, dates) are good sources of iron. II- Requirements: - Adults: 10 mg/day. - Pregnant and lactating women: 30 mg/day. III-ABSORPTION & TRANSPORT: 1- Absorption of iron occurs in the duodenum and the proximal part of the jejunum. 2- Diet contains about 10-20 mg iron/day. Usually only 10- 20% of this amount is absorbed. 3. Mechanism: Mucosal block theory a) According to this theory, iron is absorbed in the ferrous state (Fe++). Inside mucosal cells, it is oxidized to ferric state (Fe+++) and combines with apoferritin to form ferritin. b) Ferritin liberates ferrous ions by the action of reductase into the capillaries (plasma) and apoferritin is regenerated again. The rate of this liberation depends on body needs. c)The intestinal content of apoferritin is limited and when all apoferritin molecules become saturated with iron, absorption is BLOCKED FORMATION OF FERRITIN IV-IRON CONTAINING PROTEINS:  CLINICAL ABNORMALITIES: A-IRON DEFICIENCY ANEMIA: O Causes: 1- Decreased intake e.g. malnutrition. 2- Decreased absorption e.g. achlorhydra (absence of HCl). 3- Increased loss as in hemorrhage, delivery and in heavy menstruation. 4- Increased requirements as in pregnancy & lactation. 5- Heavy infestation by parasitic worms (helminths) such as tapeworms, flukes, and round worms.  Clinical abnormalities: B- Iron overload O Causes: l- Repeated blood transfusion. 2- Intravenous administration of iron. 3- Hemochromatosis (bronze diabetes): a. This is a rare hereditary disease characterized by abnormal increase of iron absorption. b. Iron is deposited in the form of hemosiderin in: -Liver: causing liver cirrhosis, -Pancreas: causing fibrosis and diabetes mellitus. -Skin: causing bronze discoloration of skin.  II.ZINC A. Sources: Meat, liver, eggs, seafood, milk, and whole grain cereals. B. Absorption: Zinc absorption occurs mainly in small intestine,. C. Functions of Zinc: 1. Zinc is essential for growth and reproduction. 2. It plays a role in tissue repair and wound healing. 3. Zinc forms a complex with insulin in ꞵ islet cells of pancreas. This helps storage and release of insulin. (Insulin when stored in the beta cells of pancreas contains zinc, which stabilizes the hormone molecule. But the insulin released into the blood does not contain zinc) 4-Zinc containing protein, Gusten, in saliva is important for taste sensation. 5. Zinc is essential component of a number of enzymes e.g.: a) Alkaline phosphatase. b) Carbonic anhydrase. c) Superoxide dismutase (SOD) d) RNA polymerase. QUESTIONS 1. Classify Minerals 2. Enumerate Factors affecting Calcium absorption 3. Function of phosphorus REFERENCES: 1 Lippincott’s: Illustrated Review Biochemistry. 2 Harpers Illustrated Biochemistry Thank You SUE