1. Primary structure of proteins refers to the linear sequence of amino acids in a polypeptide chain connected by peptide bonds. Peptide bonds are covalent and rigid, adopting a planar trans configuration. 2. Glutathione is a tripeptide that contains a sulfhydryl group and plays an important role in detoxification reactions in the body by conjugating with toxins and metabolites. 3. Denaturation refers to the loss of tertiary and quaternary structure in a protein resulting in changes to its physical and chemical properties, such as decreased solubility and activity, though the primary structure remains intact. Denaturation can be caused by physical factors like heat or chemicals and is usually irreversible

1. Structure of Proteins
PRIMARY STRCUTURE

2. o Peptide bond
o Properties of proteins
o Biologically important peptides

4. Peptide bond
 covalent
 rigid and planar with partial double bond in character.
 trans configuration.
 Both -C=O and –NH groups of peptide bonds are polar
 involved in hydrogen bond formation.
Peptides containing >10 amino acids - polypeptides.

5. Glutathione

6. WHAT IS THE AVERAGE NUMBER OF HIGH ENERGY BONDS REQUIRED
FOR THE SYNTHESIS OF ONE PEPTIDE BOND
A 1
B 2
C 3
D 4

8. OVAL ALBUMIN GLOBULAR
INSULIN
SHAPE

9. ratio Lys + Arg/( glu + Asp)
ratio > 1 Basic proteins.
Acidic proteins, ratio <1 .

10. Precipitation of proteins

12. . Milk forms a solid curd on standing
· bacteria in milk grows
· forms lactic acid
pl 4.6 For casein
· becomes isoelectric
· coagulates into a solid curd
PRECIPITATION AT pI

16. Higher is the protein molecular weight, the lower is the salt required
for precipitation
globulins are precipitated by half saturation with ammonium sulfate
albumin is precipitated by full saturation.
Salting out procedure is Used for separating serum albumins from
globulin

18. Biuret Test

19. Chemical Reaction in the Biuret test

20. NINHYDRIN REACTION GIVES A PURPLE COLOUR AND EVOLVES CO2
A WITH PEPIDE BONDS
B WITH HISTAMINE
C WITH ASPARAGINE
D WITH SEROTONIN

21. INTACT PEPTIDE BOND IS NECESSARY FOR WHICH
TEST
A UV DIFFRACTION
B NINHYDRIN
C DIAZO REACTION
D ALL

22. MILLONS TEST IS POSITIVE IN
A MAPLE SYRUP URINE
DISEASE
B HARTNUP DISEASE
C WILSONS DISEASE
D TYROSINOSIS

23. MILLONS TEST IS USED IN THE DETECTION OF
A PHENYL ALANINE
B CYSTINE
C TYROSINE
D TRYPTOPHAN

24. CYSTINURIA IS DIAGNOSED BY WHICH TEST
A FOLINS COICALTEAUS TEST
B MILLONS TEST
C XANTHOPROTEIC TEST
D CYANIDE NITROPROSSIDE TEST

25. HOPKINS COLE REACTION DETECTS AMINO
ACID CONTAINING INDOLE RING
A ARGININE
B TRYPTOPHAN
C TYROSINE
D HISTIDINE

26. BIOLOGICALLY IMPORTANT PEPTIDES

28. Meister cycle in intestine

29. Glutathione is involved in detoxication
sorganophosphates,nitro compounds are converted to
mercapturic acids

30. WHICH OF THE FOLLOWING IS TRUE ABOUT GLUTATHIONE
A CONTAINS SULFHYDRYL GROUPS
B FORMS MET Hb FROM Hb
C TRANSPORT AMINO ACID ACROSS CELL MEMBRANE
D PART OF ENZYMES

31. REGARDING GLUTATHIONE WHICH OF THE FOLLOWING IS TRUE
A IT HELPS THE ABSORPTION OF AMINO ACIDS
B IT INACTIVATES SOME ENZYMES
C IT HELPS IN MEMBRANE TRANSPORT
D IT HELPS IN CONJUGATION REACTIONS

32. IN GLUTATHIONE WHICH AMINO ACID IS REDUCING
A GLUTAMIC ACID
B GLYCINE
C CYSTEINE
D ALANINE

33. GASTRIN

34. SECRETIN

35. Vassopressin

36. Vasopressin
• Vasopressin is also called ADH (antidiuretic hormone)
• Vasopressin increases blood pressure and inhibits
diuresis.
• It constricts blood vessels rising the blood pressure and
affecting water and electrolyte balance

40. Gramicidin S
Gramicidin S is an antibiotic for topical
use and effective for gram-positive
bacterial infection.

41. TRH

43. Denaturation
LOST : quaternary , tertiary , secondary structure
INTACT : PEPTIDE BOND
DISORGANISATION OF NATIVE PROTEIN STRUCTURE
PHYSICAL , CHEMICAL , BIOLOGICAL PROPERTIES CHANGED
SOLUBILITY ↓ VISCOSITY ↑ ACTIVITY ↓
,

44. Denaturationis associated with increase in ionizable and
sulfhydryl groups of protein.
due to loss of hydrogen and disulfide bonds

45. Denaturation Usually irreversible
cooking eggs
Denatured protein is easily digested.
increased exposure of peptide bonds to enzyme
Cooking , HCL causes protein denaturation
Protein is easily digested by PEPSIN

46. haemoglobin
salicylate

47. Flocculation : protein precipitation at isoelectric pH
precipitate is referred to as flocculum.
Casein (milk protein) can be easily precipitated when adjusted
to isoelectric pH 4.6 by dilute acetic acid.
Flocculation is reversible.
On application of heat, flocculum can be converted into an
Irreversible mass, coagulum.

48. Coagulation : The term 'coagulum' refers to semi-solid
viscous precipitate of protein.
lrreversible denaturation
lowest temperature at isoelectric pH.
Albumins and globulins are coagulable proteins.
Heat coagulation test used to detect albumin in urine.

49. Agents of denaturation
Physical agents : Heat, violent shaking, X-ravs, UV rays
Chemical agents : Acids, alkalies, organic solvents (ether,
alcohol), salts of heavy metals (Pb, Hg), urea, salicylate.

50. All are true about denaturation except
A all bonds are disrupted except peptide bond
B all structures are disrupted except primary structure
C function is preserved
D on removal of denaturing force renaturation
normally does not occur

51. HEAT TEST FOR PROTEIN
 Take 2/3 of test tube full of urine sample hold the test tube from
the bottom and heat the top portion of tube.
 add a drop of 1%acetic acid .do not mix
 Normally when urine ph is acidic
 White precipitate in the heated portion
 indicating the presence of albumin

52. if urinary ph is alkaline
 proteins may not be precipitated owing to formation of
meataproteins which are not precipitated on heating
 phosphates will be precipitated and give a false positive test
 on acidification with 1% acetic acid drop by drop
 phosphate will disappear and
 precipitate of albumin will appear on acidification

53. PROTEIN ESTIMATION TEST IS CONFUSED WITH
A PHOSPHATE
B NITRATE
C SULPHATE
D BILE SALTS