Protein & Amino Acids Chemistry PDF

Protein & amino acids Chemistry ❖ By the end of this lecture, the students should be able to: 1. Describe the general structure of amino acids 2. Classify amino acids according to chemical , nutritional and metabolic classification 3. List the biological importance of proteins 4. Describe...

Protein & amino acids Chemistry ❖ By the end of this lecture, the students should be able to: 1. Describe the general structure of amino acids 2. Classify amino acids according to chemical , nutritional and metabolic classification 3. List the biological importance of proteins 4. Describe the general structure of proteins 5. Classify proteins 6. Summarize the characteristics of each type of the proteins I. Amino acids 1) Definition 2) General Structure 3) Classification a) Chemical classification b) Nutritional classification c) Metabolic classification II. Protein 1. Definition 2. General structure 3. Biological importance 4. Classification a) Simple protein b) Conjugated protein c) Derived protein A 35-year-old female came to your clinic to discuss her plans for a. new vegetarian diet. She heard from a friend about a new vegetarian diet that promised rapid weight loss. The diet consists of many leafy vegetables with no animal proteins at all. She is also planning of running a marathon within the year. After listening to her, you referred her to a nutritionist for further assistance and guidance. Amino acids 1. Definition 2. General Structure 3. Classification  1.Definition of amino acids ✓ Amino acids are the structural units (building block) of proteins. ✓They are obtained from protein by acid , alkali or enzymatic hydrolysis. ✓ There are 20 known amino acids (21 after adding selenocysteine aa) 2.General structure of amino acids Each amino acid has the following groups or chain: of amino acids general structure C O O H group NH2 group which is characteristic Side Chain ( R) for each amino acids. 3.Classification of Amino Acids Three classifications for amino acids: A)Chemical B) Nutritional C) Metabolic classification classification classification 1. Neutral 1. Essential 1. Glucogenic 2. Acidic 2. Non-essential 2. Ketogenic 3. Basic 3. Mixed glucogenic & ketogenic  A) Chemical classification of AAs According to the number of amino group and carboxylic group Neutral AA Acidic AA Basic AA NH2 = COOH COOH > NH2 NH2 > COOH (Neutral) (carry –ve charge) (carry +ve charge) 1 1 1 2 1 1 2 1 Glycine, alanine, valine, leucine, Acids: AHLy: A: Arginine isoleucine. Aspartic acid H: Histidine Cysteine, cystine, methionine Glutamic Acids L: Lysine phenylalanine, tyrosine, tryptophan] B) Nutritional classification of AA Essential AA Non-essential AA They are not synthesized in the body They are synthesized in the body. They should be taken in diet They are not essential to be taken with diet. Try This VIP Mall The rest of amino acids ✓ 1- Try: tryptophan ✓ Cysteine- cystine ✓ 2- This (threonine, histidine) ✓ Proline – hydroxyproline ✓ 3- VIP( Valine, isoleucine, phenylalanine) ✓ Aspartic- glutamic ✓ 4- Mall (Methionine, arginine, leucine, lysine) ✓ Glycine- alanine ✓ Serine –tyrosine Arginine is a semi essential AA synthesized in our body but in small, nonsufficient amount  C) Metabolic classification of AAs Ketogenic AA Mixed Glucogenic AA Glucogenic & ketogenic AA They are Ketone bodies only Carbohydrate & Carbohydrate only converted to Ketone bodies Example Only 2 AA are pure FITTT The remaining 13 AA are pure ketogenic : glucogenic F: Phenylalanine Leucine I: Isoleucine Alanine, arginine, asparagine, aspartic Lysine T: Tyrosine Glutamic, glutamine, glycine T: Tryptophan Cysteine, histidine T: Threonine Methionine, proline, serin, Valin  Protein 1. Definition 2. Biological importance 3. Classification 1.Definition & general structure of Proteins Proteins are: ❖Organic complex nitrogenous compounds ❖ Formed of C,H,O,N (+/- S) ❖Forming polymers (chains) of amino acids= (polypeptides) ❖ The amino acids are connected together by peptide link (-CO-NH-) Peptide link (where COOH gp of the 1st AA unites with the NH2 gp of the 2nd AA and so on) ❖ Ends of the polypeptide chain: ✓ COOH group: at one end → called C-terminal ✓ NH2 group: at the other end → called N-terminal 2.Biological importance of Proteins Formation of: 1. Enzymes 2. Hormones (protein hormones) 3. Hemoglobin 4. Plasma protein (lipoproteins) 5. Immunoglobulins (antibodies) 6. Supporting structure (cartilage, skin, nail, hair, etc) 3.Classification of protein Classification of proteins Conjugated Simple proteins (compound) Derived proteins proteins Product of Formed only Formed from hydrolysis of of amino protein + non simple or acids protein part compound proteins A) Simple proteins Definition: They are proteins that on hydrolysis gives only amino acids Types : (7): Albumin, Globulin, Histone, Glutelin, Prolamin, Protamine, Albuminoids Albumin Globulin Histones Albuminoids (scleroproteins) (4 not) Keratin Collagen 1. Egg: egg albumin 1. Eg g : egg globulin 1. Globin of Hair, nail, Skin, 2. milk: lactalbumin 2. milk : lactoglobulin. Hemoglobin connective tissue 3. Blood :serum 3. Blood: serum globulin 2. With Nucleic acid Tendon, bones albumin Coagulated by heat Not Coagulated by (4 NOT) Coagulation= change in the structure of protein heat Not coagulated by heat (from a liquid form to solid or a thicker liquid) Not digested by enzymes Not soluble Not in plant Supportive, protective function Gelatin** Gelatin** ✓ Obtained from collagen by boiling ✓ Forming gel by cooling ✓ Easily digested ✓ It is not adequate diet ( deficient in some AA as tryptophan). B) Conjugated (Compound) protein Definition: They are protein conjugate with non protein part (other groups) Types of conjugated proteins :(6) Types Non protein part Example Function 1. Glycoprotein Hormones(FSH,LH) Carbohydrates Antibodies, Blood gp A antigen 2. Lipoproteins Lipid Chylomicrons, VLDL, LDL,HDL Lipid transport in blood 3. Phosphoproteins Phosphoric acids Caseinogen main protein of milk 4. Metalloproteins Metals a-Ceruloplasmin(Cu) a. carry & store copper (Cu) Cu, Zn, Fe b-Insulin ( Zn ) b. Regulation of blood glucose c-Ferritin ( Fe) c. storage of Fe 5. Chromoproteins Pigment 1 Hemoproteins (red pigment) 1 Hemoglobin(HB) & Cytochromes 1HB: O2 transport& Cytochromes: electron transport 2 Flavoproteins (yellow pigment) 2 FAD/FMN 2 Reducing equivalent 6. Nucleoproteins Nucleic acids -Chromosome (Histone + DNA) 1- DNA -Ribosome (protein + RNA) 2- RNA C) Derived protein Definition: These are the denaturated or hydrolytic products of simple or conjugated proteins. Types of derived proteins: (2) 1-Primary protein derivatives 2-Secondary protein derivatives 1. Definition They are Products of protein They are Products of protein hydrolysis denaturation 2. Derived by Action of denaturing agents on protein Action of hydrolysing agents on protein (eg. heat denaturation) (eg. Enzymatic hydrolysis) 3. Peptide bond No peptide bond break Peptide bonds break (no change in molecular weight (MW)) (decrease in molecular weight) 4. Example 1. coagulated albumin 1. Proteose 2. coagulated globulin 2. peptone 3. peptide. 4. Amino acids  eg. coagulated albumin 1ry proteins derivatives 2ry proteins derivatives  REFERENCES ❑ Chatterjea’s Textbook of Medical Biochemistry, 8th edition. ❑ Vasudevan's Textbook of Biochemistry For Medical Students, 6th Edition. ❑ Lippincott’s Illustrated Reviews: Biochemistry, 8th edition