Nutritional Biochemistry Lecture Notes PDF

Nutritional Biochemistry BIOCH 209 (BIOCH 209) Level 4 (2nd Year, 2nd Semester) Introduction Arafat Goja, PhD Lecture 2: Clinical Nutrition Department...

Nutritional Biochemistry BIOCH 209 (BIOCH 209) Level 4 (2nd Year, 2nd Semester) Introduction Arafat Goja, PhD Lecture 2: Clinical Nutrition Department January 20, 2025 Imam Abdulrahman Bin Faisal University 1  Topic to be covered in this lecture: Definition of Biochemistry and its importance. Understand why biochemistry is important in nutrition fields Understand Biochemistry of the molecules and their processing in the living cells Outline chemistry of carbohydrates, Lipids ( Fats/Oils) and Proteins. Describe Physical & chemical properties of carbohydrates, Lipids ( Fats/Oils) and Proteins The roles and fate of macronutrients: ✓ Carbohydrates ✓ Lipids ( Fats/Oils) ✓ Proteins 2  Biochemistry: Definition Biochemistry: Definition ✓ ‘’bios’’ Greek word which means “life” ✓ Biochemistry is language of biology. ✓ It is fundamental for study and understanding all biological process. ✓ The study of biochemistry is essential to understand basic functions of the body. ✓ Biochemistry: is the study of chemical process going on in the living organism at the molecular level. ✓ Besides, also deal with the nature of chemical constituents, functions and reaction happening in the living cells of all organisms 3 Biochemistry: Scope Knowledge of biochemistry is very important in many sectors such as: ✓ Microbiology, ✓ Cell biology, ✓ Physiology, ✓ Pathology, ✓ Immunology, ✓ Molecular biology, ✓ Genetics, ✓ Botany, ✓ Nutrition, ✓ and …etc 4  Biochemistry & Nutrition Biochemistry and Nutrition “Every Nutrition Process has a biochemical basis” 5 Why biochemistry is important in nutrition fields Biochemistry and Nutrition Biochemistry Nucleic acid Proteins Lipids Carbohydrates Genetics Growth/ Energy/ Energy information Repair Protection Digestion Diseases Build cell Regulation Weight Structure Diseases Blood sugar Nutrition 6 Why we study Nutritional Biochemistry? Nutritional Biochemistry ✓ To investigate the impact of nutrition on both physical and mental health of human. ✓ To understand the interactions between diet and disease. 7 Carbohydrates Carbohydrates Introduction: Carbohydrates are widely distributed both in animal and plants tissues as glucose/glycogen and starch, respectively. Definition: known as “hydrates of carbon” A polyhydroxy aldehydes (H-C=O-) or ketones (C-C=O-) contains a number of alcohol groups (‐OH) with the empirical formula Cm(H2O)n Functions: 1- Main source of energy in the body, e.g. Glucose 2- Cell membrane components e.g. Glycoprotein and glycolipids 3- Structure components of many organism e.g. Cellulose 4- Most important in DNA& RNA nucleotides e.g. Ribose sugar 9 Classification of Carbohydrates Carbohydrates are classified into 4 groups : I. Monosaccharides: (Greek, mono = one) Sugar cannot be further hydrolyzed into smaller unit II. Disaccharides: Two monosaccharides combined with elimination of water molecules (-H2O ) III. Oligosaccharides:(Greek, oligo = a few) from 3, 4, 5, …less than/or10 sugars IV. Polysaccharides:(Greek, poly = many) more than 10 sugars units are combined 10 Classification & structure of Carbohydrates I. Monosaccharides (Cn(H2O)n): (Simple sugar) Classified according to three different characteristics: 1- Number of carbon atoms 2- The placement of its carbonyl group, 3- Chiral carbon handedness ("left-handed" form (L form) and a "right-handed" form (D) form). All Monosaccharaides can be derived from glyceraldehyde (C3). 11 Monosaccharideds I. Monosaccharides: (Simple sugar) cont… 12 Monosaccharideds L &D Sugars: Note:- only D-sugars are metabolized by the human body and all naturally occurring sugars are D- sugars 13 Disaccharides(C12H22O11) Disaccharides(C12H22O11): (Two sugars linkages with O-glycosidic bond) that can be made from same or different monosaccharides. Type of glycosidic bonds: - α-glycosidic bond: linkage between a C-1α OH and a C-4 OH - β-glycosidic bond: linkage between a C-1 β OH and a C-4 OH 14 Disaccharides(C12H22O11) Disaccharides(C12H22O11): Maltose: D-Glucose + D-Glucose ✓ Obtained by acid or enzymes hydrolysis of starch ✓ Very soluble in water and has reducing properties ✓ It is widely used in infant feeding Lactose: (β-D-Galactose+ β-D-Glucose) ✓ Milk sugar (β-D-Galactose+ β-D-Glucose) ✓ It is no very soluble and is not so sweet ✓ It has reducing properties and can form osazones Sucrose: table sugar or Cane sugar (α-D-Glucose + -β-D-Fructose) ✓ Obtained from sugarcane or sugar beet ✓ Occurs free in most fruit and vegetables ✓ It is invert sugar ✓ Very soluble and sweet ✓ It does not exhibit reducing properties, why? 15  Oligosaccharides Oligosaccharides: ✓ Is a saccharide polymer containing a small number of ( typically 3 to about of 10 or 12) monosaccharides units, that Dextrin can be made from same sugar units (homopolysaccharides) or different (Heteropolysaccharides) Example: Dextrin, Raffinose, Stachyose ✓ Dextrin: is an intermediate product in the conversation of starch to maltose ✓ Raffinose: sugar found in in legumes, whole grains, cabbage, broccoli, cotton seed, …etc. ✓ Stachyose: use as sweetener, less than sucrose, occurs naturally in numerous vegetables: green beans, soybeans and other beans 16 Polysaccharides Polysaccharides: ✓ Are a complex of carbohydrates joined together by glycosidic bond ✓ Contains more than 10-12 monosaccharides units (up to 1000) can be linear or highly branched. ✓ Can be divided to: 1- Homopolysaccharides 2- Heteropolysaccharides) 17  Polysaccharides Polysaccharides: ✓ Homopolysaccharides 1- Starch: - composed from amylose and amylopectin - It is an insoluble in cold water Amylose: 15 – 20% Amylopectin: 80 – 85% straight chain of glucose (unbranched) High branched of glucose structure. soluble in water Insoluble in water, can absorb water and swell up. include 250 to 300 D- Glucose units linked (α1- 4 18  Polysaccharides Polysaccharides: ✓ Homopolysaccharides 2- Cellulose: it is a polymer of Glucose. Very stable insoluble compound. Have no nutritional value to human body. Most abundant polysaccharide. enhance and elimination of indigestible food residue. Most abundant polysaccharide. It consider as dietetic value (add bulk to intestinal contents). β (1 - 4) glycosidic linkages 3- Dextrin: Occurs when starch hydrolyzed with acids or enzymes. Widely used in infant feeding Contain 3-8 glucose units 4- Glycogen (animal starch): It is a polymer of D-Glucose Similar to amylopectin but highly branched Storage in liver and muscle in Humans and other vertebrates 19  Polysaccharides Polysaccharides: ✓ Heteropolysaccharides: Polysaccharides conjugated with another compound (attached by glycosidic bond to non-glycosidic bond) such as protein or lipids 1- Proteins (Glycoprotein) - Heparin - Blood group substances 2- Lipids (Glycolipids) 20 Physical & Chemical Properties of Monosaccharides Physical Properties of Monosaccharides Monosaccharides are: ✓ Colorless ✓ Sweet in test ✓ Quite soluble in water ✓ Crystalline solids at room temperature ✓ Stereo isomerism D-glucose and L-glucose are mirror images of each other. 22  Reducing Sugars Reducing Sugars ✓ If the oxygen in anomeric carbon(aldehyde or ketone functional groups) is free (not attached) that sugar is reducing sugar and define as: “A sugar acts as reducing agent and can effectively donate electrons to some other molecule by oxidizing, it is called reducing sugar” ✓ All monosaccharides are reducing sugars, because the oxygen in carbonyl group is free, either cyclic or open chain form. ✓ Disaccharides , lactose and maltose (except sucrose) are reducing sugar, because there is a free anomeric carbon in one of the glucose molecules. Free reducing end 23  Reducing Sugars Reducing Sugars ✓ Disaccharides sucrose) is not reducing sugar WHY? 24 Reduction of Monosaccharaides Reduction of carbonyl carbon( Aldehyde or keto group) produces a new Sugar alcohol. Such as Glucose reduced = form sorbitol, Mannose = form mannitol, Glyceraldehyde = form glycerol. 25 Oxidation of Monosaccharaides 26  Oxidation of Monosaccharaides Oxidation of Monosaccharaides Aldoses sugars my Oxidized to 3 types of acids: 1. Aldonic acids: aldehyde group converted to carboxy group (C-OOH) Ex: Glucose - Gluconic acid, Galactose - Galctonic acid, Mannose - Mannonic acid 2. Alduronic acids: the alcohol at the end, opposite to the aldehyde is oxidation to carboxy group. EX: Glucose - Glucuronic acid, Galactose - Galacturonic acid. Mannose - Mannuronic acid 3- Saccharic acid: oxidation at both end of monosaccharaides Ex: Glucose - Glucosaccharic acid, Mannose – Mannaric acid 27