PROTEIN-CHEMISTRY-BIOLOGY-SCIENCE23.pptx

This powerpoint is about proteins. It is effective and useful. It is student friendly. It is understandable for students struggling with chemistry, specifically biochemistry. Proteins are very essential in our body.

1. PROTEINS

2. O U T L I N E Sources of Proteins Isolation and Isoelectric precipitation of proteins Elementary composition of proteins Qualitative color reaction Protein hydrolysis Denaturation

3. PROTEINS a naturally occurring, unbranched polymer in which the monomer units are amino acids. More specifically a protein is a peptide in which at least 40 amino acids residues are present.

4. GLUTEN proteins, glutenin i s a m i x t u r e o f t w o a n d gliadin. It is also the composite of a prolamin and glutelin, which exist, conjoined with starch, in the endosperm of various grass-related grains. g l u t e n i n , w h i c h is The prolamin and glutelin from wheat (gliadin, which is alcohol-soluble, and on l y s o l ub l e i n d i l u t e a c i d s or a l k a li s ) c o n s t i t u t e 80% of the a b ou t p r o t e i n contained in wheat fruit.

5. GLUTEN (from Latin gluten, "glue") is a protein composite found in wheat and related grains, including barley and rye. Gluten gives elasticity to dough, helping it rise and keep its shape and often gives the final product a chewy texture.

6. Washings remained clear after iodine test, indicating removal of all starch. The principle involved in the isolation of gluten is difference in solubility. The starch is partially soluble in water while gluten is insoluble in water. Thus, gluten can be separated from starch. Iodine solution is used to test the complete removal of starch, which involves the formation of blue-iodo starch complex. Refrigeration keeps the protein from degrading.

7. Qualitative Color Reaction

8. Qualitative Color Reaction Biuret Ninhydrin Xanthoproteic Millon’s Hopkins-cole Sakaguchi Lead acetate or lead sulphide Lieberman Molisch Sodium Nit r o prusside Follins reaction Sullivan/ sulliven cysteine rxn Pauly diazo test

9. Write the Qualitative Color Reaction test that matches with the description: Rose-pink to violet then purple – due to peptide linkages Deep blue color to violet or purple - presence of free amino group * Yellow w/ HNO3 & to orange w/ NaOH * - nitration of benzene ring of aromatic amino acids (Y,W,F) Flesh to red or brick red complex with mercurous nitrate in HNO3 , AA with phenol group, Tyrosine Reddish violet ring at the junction w/ Magnesium salts of oxalic acids – presence of indole group/ tryptophan Deep Red color w/ a- naphthol & sodium hypochlorite or bromite – arginine Black precipitate – methionine, cysteine, cystine Violet color – tryptophan Violet ring – glycoprotein (ex. gamma-globulin) Red color – cysteine Deep red color in alkaline sol’n w/ sodium 1,2 n a pth o q u in o n w -4 s ul f o n a t e – as quantitative estimation of AA Red color w/ strong reducing agent sodium hydrosulfite – cysteine and cystine quatitative estimation Red color in alkaline solution treated with diazotized sulfanilic acid – tyrosine & histidine

10. Qualitative Color Reaction Biuret Ninhydrin Xanthoproteic Millon’s Hopkins-cole Sakaguchi Lead acetate or lead sulphide Lieberman Molisch Sodium Nitroprusside Follins reaction Sullivan/ sulliven cysteine rxn Pauly diazo test

11. HYDROLYSIS OF INTACT PROTEINS

12. HYDROLYSIS chemical reaction in which water is used to break down bonds of a particular substance reaction with water/ breaking using water

13. PROTEIN HYDROLYSIS generally only used in the determination of tryptophan , since other amino acids are degraded. ALKALINE HYDROLYSIS

14. PROTEIN HYDROLYSIS cystin e , cys t eine, a n d unde rgo met h i o n ine variable d egr a da t i o n thr o ugh o x i d a t i on during acid hydrolysis Tyr osi n e lo s s e s c an also occur due to oxidation, but this may be reduced by the addition of phenol to the HCl. ACID HYDROLYSIS

15. PROTEIN HYDROLYSIS is rarely used except for the determination of gl u tamin e a nd asparagine , which are converted to aspartic and glutamic acids together with ammonia by acid hydrolysis.. ENZYMATIC HYDROLYSIS

16. ACID HYDROLYSIS -Water molecule would give away proton (water acts as BASE) -Tryptophan is destroyed -Serine and Threonine are decomposed

17. ALKALINE HYDROLYSIS -random breaking of nearly 40% of all the peptide bonds in protein -also occurs in small intestines after we eat, hydrolysed by digestive enzymes -function efficiently in slightly alkaline pH (8-8.5) -Water acts as ACID

18. ENZYMATIC HYDROLYSIS - a process in which enzymes enhance bond cleavage in molecules with the addition of the elements of water -determination of glutamine and aspargine which are converted to aspartic acid an glutamic acid ENZYMES Lipase- fats Amylase- carbohydrates Proteinases- proteins

19. ADVANTAGES & DISADVANTAGES OF ENZYMATIC HYDROLYSIS Mild process Requires less energy Produce less by-product Low reaction rate High yield of sugar monomers Usually incomplete

20. DENATURATION

21. DENATURATION i s the par t ial o r c ompl e t e di s o r g ani z a t i o n o f a p r o t ein ’ s ch a r a c t e r i s tic t h r e e - dim e ns i o na l sh a pe a s a r e s ul t of di s ru p t i o n o f i t s se c on d ar y , t er t ia r y , a n d qu a t ern a r y structural interactions Causes inactivation of protein activity Caus e s loss o f w a t er s olubi l i t y o r r ende r s the p r o t e i n insoluble at isoelectric point

22. DENATURATION the process of altering the native/low free energy conformation of a protein Peptide bonds remain intact and the protein usually retains its original primary structure Principle: Denatured protein can return to its native state and resume its specific biological activity.

23. COAGULATION vs FLOCCULATION F L O CCU L A T I O N C OA GU L A T I O N reversible clumping together of the dispersed chains of denatured proteins when the forces of mutual repulsion is at minimum. Agglomeration of destabilized particle into a large size particle known as flocs which can effectively be removed by sedimentation or floatation. – matted mass of heated flocculated protein (like in egg albumin)

24. Denaturing agents and Mode of action

25. PRECIPITATION: PRECIPITANTS BY ACIDS BY SALTS OF HEAVY METALS BY ALCOHOL

26. Organic acids trichloracetic acid phosphomolybdic acid phosphotungstic Picric acid Tannic acids

27. Organic acids: TANNIC ACID Topically, tannic acid is used for cold sores and fever blisters , diaper rash and prickly heat, poison ivy, ingrown toenails, sore throat, inflamed tonsils, spongy or receding gums, acute dermatitis, and as a styptic. Tannic acid is used orally and topically for bleeding, chronic diarrhea, dysentery, bloody urine, painful joints, persistent coughs, and cancer. Vaginally, tannic acid is used as a douche for leukorrhea. In foods and beverages, tannic acid is used as a flavoring agent. In manufacturing, tannic acid is used in hemorrhoidal ointments and suppositories, for tanning hides and manufacturing ink, and to kill dust mites on furniture.

28. TANNIC ACID Tannic acid has astringent effects I t d e h y d r a t es tis s u e, i n t e r n al l y r educing s e c r e tio n s , a n d e x t e r n al l y forming a protective layer of harder, constricted cells. T a nn ins s h o w s o m e e v i d e n ce of a nt i vi r al, a n t imic r o b ial, CNS depressant, and cariostatic effects . Some evidence suggests that tannins might cause cancer, but other evidence shows tannins might prevent it . R egu l ar c o n sum p tion of h e r b s with hi g h t a n n i n c o n c e n t r a tions correlates with increased incidence of esophageal or nasal cancer .

29. Inorganic acids : HNO3/ Nitric acids use d i n d e t e c ting p r e s ence o f p r o t e i n s in the urine through Heller’s test Results: white ppt. turning yellow

30. Salts of heavy metals reaction: proteins from an alkaline solution + salts of heavy metals = precipitation Ex. lead nitrate, silver nitrate, mercuric chloride metallic salts – used as antiseptic and germicides through precipitation. Ex. AgNO3 – used for cauterization of wounds and ulcers. Egg whites and milk – antidote for metallic poisoning

31. Factors affecting protein solubility 1. Effects of neutral salts (NaCl, MgSO4, (NH4)2SO4) salting in: increase solubility w/ low concentration salting out: aka antisolvent crystallization, precipitation as a result of high concentration of neutral salts

32. Factors affecting protein solubility 2. Effect of pH - solubility is minimum at isoelectric point and increases with increasing acidity or alkilinity.

33. Factors affecting protein solubility Effect of organic solvents organic solvents (miscible with water), ex. methanol, ethanol and acetone. decrease dielectric constant inc r ease e l ec t r o s t a t ic f o r ces b e t w e e n charged particles in solution.

34. Factors affecting protein solubility 4. Effects of Alcohol dilute solution: alcohol reduces the solubility of proteins due to an increase in the electrical forces between charged particles in solution. High alcohol concentration: protein molecules are dehydrated . More precipitation. 95 % alcohol – less germicidal 70 % alcohol – with greater germicidal effect

35. END