1. BIOCHEMISTRYLABORATORY(Midterm)Geromil J. Lara, RMT, MSMT
2. ACTIVITY 1A /1B Subcellular Components of the Living Cell• 5% Trichloroacetic Acid – Suspending medium – Able to precipitate proteins – Good fixative and preservative
3. ACTIVITY 1A /1B Subcellular components of the Living Cell• Sediment 1 – Nuclear Fraction – Nuclei and Unbroken Cells• Sediment 2 – Mitochondria• Sediment 3 – Microsome – Proteins, Enzymes, Inorganic Ions
4. ACTIVITY 1A /1B Subcellular components of the Living Cell• Qualitative Tests – Carbohydrates • Molisch Test • Benedict’s Test – Proteins • Biuret Test • Xanthoproteic Test – Lipids • Sudan Test • Acrolein Test
5. ACTIVITY 1A /1B Subcellular Components of the Living Cell• Carbohydrates – Molisch Test 5 drops of the supernate + Molisch Reagent shake Layer with 1 mL conc. H2SO4Control: 1% LecithinMolisch Reagent: α-Naphthol dissolved in Ethanol
6. ACTIVITY 1A Subcellular components of the Living Cell• Carbohydrates – Molisch Test 5 drops of the supernate + Molisch Reagent shake Layer with 1 mL conc. H2SO4Principle: when sugar solution is mixed with alpha- naphthol is brought in contact with conc. H2SO4, a violet ring is formed at the junction of the 2 liquids
7. ACTIVITY 1A Subcellular components of the Living Cell• Carbohydrates – Molisch Test 5 drops of the supernate + Molisch Reagent shake Layer with 1 mL conc. H2SO4H2SO4 : acts as dehydrating agent forming furfural derivatives which interact with alpha-naphthol liberating a colored compound
8. ACTIVITY 1A /1B Subcellular Components of the Living Cell• Carbohydrates – Benedict’s Test 1 mL of Benedict’s Reagent + 2 drops of supernate Boil for 2 minutes and allow to coolBenedict’s Reagent: Sodium Citrate, Sodium Carbonate, Sodium Hydroxide, and Copper Sulfate
9. ACTIVITY 1A/1B Subcellular components of the Living Cell• Carbohydrates – Benedict’s Test• used to detect the presence of all monosaccharides, and generally all reducing sugars• Will detect the presence of aldehydes (except aromatic ones), and alpha-hydroxy-ketones, including those that occur in certain ketoses
10. Benedict’s TestCuSO4 + 2NaOH Cu(OH)2 + Na2SO42Cu(OH)2 Cu2O + 2H2O (Brick Red Precipitate)Blue = (-)Green, Yellow, Orange, Red, & then Brick Red precipitate = (+)
11. ACTIVITY 1A /1B Subcellular components of the Living Cell• Proteins – Biuret Test 5 drops of the supernate + 5 drops 10% NaOH + 0.5% CuSO4Control: 1% AlbuminBenedict’s Reagent: Sodium Hydroxide and Copper Sulfate
12. ACTIVITY 1A /1B Subcellular Components of the Living Cell• Proteins – Biuret Test• Alkaline solution of proteins treated with copper sulfate results in the production of a rose-pink to violet, then purple• Test used to detect the presence of peptide bonds by hydrolysis• (+) – a copper(II) ion is reduced to copper(I), which forms a complex with the nitrogens and carbons of the peptide bonds in an alkaline solution
13. ACTIVITY 1A /1B Subcellular Components of the Living Cell• Proteins – Xanthoproteic Test 1 mL of the supernate + 1 mL conc. HNO3 heat add 5 drops NH4OH• Proteins when treated with conc. nitric acid turn yellow to orange when neutralized with sodium hydroxide• Due to the nitration of the benzene ring present in tyrosine, tryptophan, and phenylalanine
14. Tyrosine Tryptophan Phenylalanine
15. ACTIVITY 1A /1B Subcellular components of the Living Cell• Lipids – Sudan Test 5 drops of the supernate + 5 drops of Sudan IV (Red)• Control: 1% Lecithin• Sudan IV: fat-soluble dye used for the staining of lipids, triglycerides, and lipoproteins
16. ACTIVITY 1A /1B Subcellular Components of the Living Cell• Lipids – Acrolein Test 0.5 g of KHSO4 + a drop of the supernate heat odor of burnt grease• Lipids when heated with potassium bisulfate will release acrolein• Glycerol portion is dehydrated to form unsaturated aldehyde (acrolein)
17. ACTIVITY 2A Qualitative Tests for Proteins• Millon’s Test 1 mL egg albumin + 2 drops Millon’s reagent mix and heat (+) flesh precipitate to red color• Millon’s reagent: mercurous nitrate in nitric acid• Protein is precipitated as mercury salt and after heating precipitated turns flesh to red color• Due to the phenol group contained in tyrosine
18. ACTIVITY 2A Qualitative Tests for Proteins• Glyoxylic Acid reaction (Hopkins-Cole Test) 1 mL egg albumin + 1 mL Hopkins-Cole reagent allow 10 drops pure conc. H2SO4• When protein mixed with glyoxylic acid and H2SO4, a violet ring will form beneath the protein mixture• Due to the presence of an indole nucleus in the tryptophan component• Tryptophan condenses with the aldehyde to form the colored product
19. ACTIVITY 2A Qualitative Tests for Proteins• Ninhydrin Test 1 mL egg albumin + 1 mL 0.1% Ninhydrin Reagent heat to boiling blue product• When protein is boiled with ninhydrin, a blue color is produced• Due to the presence of the alpha-amino acid• All proteins are positive except proline
20. alpha-amino acid + ninhydrin ---> reduced ninhydrin + alpha-amino acid + H2Oalpha-amino acid + H2O ---> alpha-keto acid +NH3alpha-keto acid + NH3 ---> aldehyde + CO2alpha-amino acid + 2 ninhydrin ---> CO2 + aldehyde + final complex(BLUE) + 4H2O
21. ACTIVITY 2A Qualitative Tests for Proteins• Sakaguchi Reaction for Arginine 1 mL egg albumin + 1 mL 10% NaOH add 6 drops dil. alc. alpha-naphthol + 10 drops Na hypochlorite• for the detection of a specific type of protein with the amino acid containing the guanidinium group to form a red color• Due to the presence of arginine
22. ACTIVITY 2B Precipitation Test for Proteins• Concentrated Minerals and Organic Acids – Concentrated H2SO4 – Concentrated HCl – Concentrated HNO3 – Glacial CH3COOH – Strong acids cause the carboxyl end of the protein to remain undissociated and all amino groups to become fully proteinated
23. ACTIVITY 2B Precipitation Test for Proteins• Metallic Salts – Mercuric Chloride – Lead Acetate – Copper Sulfate – Ferric Chloride – Barium Chloride – Positive charges of these cations counteract the negative charge of the carboxyl group giving a precipitate
24. ACTIVITY 2B Precipitation Test for Proteins• Alkaloidal Reagents – Picric Acid – Trichloroacetic Acid – Tannic Acid – Phosphotungstic Acid – Precipitation indicates the presence of both negative and positive charges and hence the ampotheric nature of proteins
25. ACTIVITY 2B Precipitation Test for Proteins• Alcohols – 95% Alcohol (2 tubes) – 1st tube: add diluted HCl – 2nd tube: add 10% NaOH
26. ACTIVITY 2B Precipitation Test for Proteins• Coagulation by Heat – Boiling the egg albumin – Add 2 drops acetic acid – Heat disrupts hydrogen bonds of secondary and tertiary structures while the primary structure remains unaffected• Millon’s Test, Xanthoproteic Test, Biuret Test, Hopkins Cole Test
27. ACTIVITY 3A: ENZYMES• Potato Extract – With starch and proteins – Rich in catalase and peroxidases
28. ACTIVITY 3A: ENZYMES• Biuret Test – Expected to have positive result – Hydrolysis of peptides
29. ACTIVITY 3A: ENZYMES• Test for Catalase Activity 5 mL of potato extract + 1 mL 3% H2O2 Observe for gas production Add 1 mL 0.5% benzidine Blue to Green
30. ACTIVITY 3A: ENZYMES• Test for Catalase Activity
31. ACTIVITY 3A: ENZYMES• Test for Specificity of Enzyme Action 1 mL 1 mL Starch 1% Glycogen + +1 mL salivary AMS 1 2 1 mL salivary AMSStand for 15 mins. at RT and perform iodine test
32. 1 Drop 1 DropSolution IodineIodine Test – Used for the presence of CHO – Potassium iodide – KI reacts with starch producing a deep purple color • Results of the formation of polyiodide chains
33. ACTIVITY 3A: ENZYMES• Iodine Test – Amylose (straight chain) • Forms helices where iodide molecules assemble – Blue-black color • Starch – Amylopectin (branched portion) • Forms much shorter helices and iodine are unable to assemble – orange/yellow hue • Glycogen
34. ACTIVITY 3B: Factors Affecting Enzyme Action• Effect of Temperature – 1% cooked starch + 1 mL saliva (amylase) – Test Tube 1: 40 degrees Celsius – Test Tube 2: 60 degrees Celsius – Test Tube 3: 10 degrees Celsius – Perform Iodine Test
35. ACTIVITY 3B: Factors Affecting Enzyme Action• Effect of pH – Coagulated Egg White to 4 tubes – Test Tube 1: 2% pepsin + 0.4% HCl – Test Tube 2: 2% pepsin + 0.4% Na2CO3 – Test Tube 3: 2% pancreatin + 0.4% HCl – Test Tube 4: 2% pancreatin + 0.4% Na2CO3 • Incubate at 40 degrees Celsius • Determine the pH • Perform Biuret Test – Control: 0.5% Peptone
36. ACTIVITY 3B: Factors Affecting Enzyme Action• Effect of pHTT 1: 2% pepsin + 0.4% HCl = AcidTT 2: 2% pepsin + 0.4% Na2CO3 = BasicTT 3: 2% pancreatin + 0.4% HCl = AcidTT 4: 2% pancreatin + 0.4% Na2CO3 = Basic
37. ACTIVITY 3B: Factors Affecting Enzyme Action• Effect of pH• Pepsin – Released by the chief cells in the stomach – Optimum activity at pH 1-2 – Degrades food proteins into peptides• Pancreatin – Produced by the exocrine cells of the pancreas – With AMS, LPS, protease, and trypsin – Optimum activity at pH 7-9
38. ACTIVITY 3B: Factors Affecting Enzyme Action• Effect of pHTT 1: 2% pepsin + 0.4% HCl = AcidTT 2: 2% pepsin + 0.4% Na2CO3 = BasicTT 3: 2% pancreatin + 0.4% HCl = AcidTT 4: 2% pancreatin + 0.4% Na2CO3 = Basic
39. ACTIVITY 4: NUCLEIC ACIDS• Liver is suspended in 5% TCA – To extract the acid soluble substance• Residue is extracted with alcohol-ether – To remove the lipids• Residue is resuspended with 5% TCA – To preserve the nucleic acid
40. ACTIVITY 4: Nucleic Acids• Test for Purine » 1 mL of test solution + 1 mL 2N HCl » Place in boiling water for 20 minutes to hydrolyze the nucleic acid to form free purines » Add 1 mL 2N HCl and 2 mL acetate buffer » Place in boiling water » Add 0.5 mL 10% CuSO4 – bluish-brown ppt » Add 0.5 mL sat. Na bisulfate » Heat and a white or light tan flocculent ppt
41. ACTIVITY 4: Nucleic Acids• Orcinol Test for Pentoses (Bial’s Test) Dilute 0.5 mL sample with 2.5 mL water add 3 mL Orcinol Reagent heat Blue Color
42. ACTIVITY 4: NUCLEIC ACIDS• Orcinol Reagent – HCl + FeCl3 – Pentose is dehydrated to form furfural – Furfural reacts with orcinol – Iron will produce a bluish product
43. ACTIVITY 4: Nucleic Acids• Diphenylamine Test for Deoxyribose 1.5 mL sample + 3.5 mL diphenylamine heat 10 minutes green-blue color
44. ACTIVITY 4: NUCLEIC ACIDS• Diphenylamine Test for Deoxyribose – Reaction depends on the conversion of the pentose to w-hydroxylaevulinic aldehyde which then reacts with diphenylamine to give a blue colored complex
45. ACTIVITY 4: Nucleic Acids• Test for Phosphates 2 mL sample + 2 mL Nitric Acid add ammonium molybdate yellow phospho-ammonium molybdate
46. CHARACERIZATION OF LIPIDSSOLUBILITY – Insoluble in water – Insoluble in ordinary solvents – Readily dissolve in chloroform, benzene, ether, boiling alcohol and other organic solvents
47. CHARACERIZATION OF LIPIDSFORMATION OF TRANSLUCENT SPOT – Lipids have a characteristic greasy feel – When brought in contact with a substance like paper, penetrate through it producing a translucent spot • Fats are non-volatile • In RT, the spot of water can absorb enough heat from the air and evaporized • But the spot of grease can never absorb enough heat to evaporized • When the liquid is inside the sheet of paper, it diffracts light – TRANSLUCENT PHENOMENON
48. CHARACERIZATION OF LIPIDSREACTION OF FATS – Fatty acids are carboxylic acids and are therefore weak acids – For fatty acids, the value of pKa is around 4.5. Therefore, generally speaking, fatty acids are neutral below pH 4.5 and charged above pH 4.5 – Fats containing high unsaturated fatty acids are neutral in reaction, but when exposed to air become acidic due to hydrolysis which results from the liberation of volatile fatty acids
49. CHARACERIZATION OF LIPIDSACROLEIN FORMATION - 2H2OGlycerol Acrolein (acrid odor) dehydrating agent (potassium bisulfate)
50. CHARACERIZATION OF LIPIDSEMULSIFICATION OF FATS
51. CHARACERIZATION OF LIPIDSEMULSION – Is a mixture of two or more materials that are ordinarily immiscible – Droplets of the dispersed component rapidly coalesce to form a separate layer – Emulsifying agent must be present to stabilize the emulsion – Lecithin in the egg will serve as emulsifier
52. CHARACERIZATION OF LIPIDSSAPONIFICATION OF LARD – Alcoholic Potash • KOH dissolved in ethanol • To neutralized fatty acids in the lard – A metallic salt of fatty acid is formed – Hydrophobic tails extend into the greasy droplets whereas the polar heads of the soap molecules face toward the water
53. CHARACERIZATION OF LIPIDSSAPONIFICATION OF LARD – Sodium Carbonate – to produce hard soapPalmitin Palmitate + Glycerol Soap
54. CHARACERIZATION OF LIPIDSSEPARATION OF CHOLESTEROL AND TRIGLYCERIDES – Precipitate = cholesterol digitonide after digitonin precipitation – Supernatant = triglycerides – PRECIPITATE tested for Salkowski Test and Liebermann-Burchardt Test • Test for cholesterol
55. CHARACERIZATION OF LIPIDSSALKOWSKI TEST – The presence of a double bond in one cholesterol rings is responsible for its ability to form color products in the presence of concentrated inorganic acids – Sulfuric acid • Results in dehydration of cholesterol molecule with a formation of a red bicholestadien disulphonate – Bluish color between the 1st layer (chloroform) and 2nd layer (H2SO4)
56. CHARACERIZATION OF LIPIDSLIEBERMAN-BURCHARD TEST – Deep green color (+) – due to the hydroxyl group (-OH) of cholesterol reacting with the reagents (acetic anhydride and concentrated sulfuric acid) and increasing the conjugation of the un-saturation in the adjacent fused ring
57. GOODLUCK