Qualitative Reaction of Proteins

Question 1

polypeptides with at least
50 amino acid residues and could
have hundreds and even thousands
of amino acid residues

Answer 1

proteins

Question 2

structure of
protein is largely determined by their
amino sequence as postulated by this
dogma

Answer 2

Anfinsen’s dogma

Question 3

Hierarchy of structural organization
of proteins

Answer 3

➢ Primary structure (1o
➢ Secondary structure (2o
➢ Tertiary structure (3o
➢ Quaternary structure (4o

Question 4

amino acid
sequence of polypeptide which starts
at the N-terminal amino acid and
ends with C-terminal amino acid

Answer 4

primary structure

Question 5

refers to the
local folding of a short segment of a
peptide into specific configurations
such as α-helix, β-sheet, or random
coil

Answer 5

secondary stucture

Question 6

over-all threedimensional shape of the protein
which can either be globular or
fibrous in conformation

Answer 6

tertiary structure

Question 7

– association of
the various sub-units of a multimeric
protein

Answer 7

quaternary structure

Question 8

play countless roles
throughout the biological world, from catalyzing chemical reactions to
building structures of all living things

Answer 8

protein

Question 9

made up of carbon,
oxygen, nitrogen, hydrogen, and
sulfur atoms

Answer 9

amino acid

Question 10

– interact with
oppositely charged amino acid or
water

Answer 10

charged amino acid

Question 11

protein chian fold into this
can form regular patterns of
hydrogen bonds between the
backbone atoms of nearby amino
acids

Answer 11

alpha-helix

Question 12

backbone atoms of the
chain can interact side-by-side to
form

Answer 12

beta-sheets

Question 13

forms a pocket to hold
heme, a small molecule with an iron
atom at the center that binds oxygen

Answer 13

hemoglobin

Question 14

its flexible arms protect
the body from disease by recognizing
and binding to foreign molecules and
thus preventing the viral RNA or DNA
to enter the cell

Answer 14

antibodies

Question 15

forms a strong triple helix
that is used throughout the body for
structural support

Answer 15

collagen

Question 16

moves ions across
cell membranes allowing the
synchronized contraction of muscles

Answer 16

calcium pump

Question 17

small, stable protein that
can easily maintain its shape while
travelling through the blood to
regulate blood sugar level

Answer 17

insulin

Question 18

enzyme that has a
catalytic site that begins the
breakdown of carbohydrates in our
saliva

Answer 18

alpha-amylase

Question 19

forms a hollow shell that
stores iron from our food

Answer 19

ferritin

Question 20

put together a model
of myoglobi

Answer 20

John Kendrew

Question 21

proteins are made up
of these

Answer 21

amino acid

Question 22

used to detect the
presence of a peptide bond and uses
alkaline/basic copper sulfate reagent

Answer 22

biuret test

Question 23

what does biuret test uses as an reagent

Answer 23

alkaline
basic copper sulfate

Question 24

forms a
coordination complex with the
nucleophilic nitrogen atom of
the peptide bond which
manifests as violet complex

Answer 24

copper ion

Question 25

violex complex is called what in biuret test

Answer 25

biurety complex

Question 26

color of biuret when negative

Answer 26

blue

Question 27

color of biuret when positive

Answer 27

deep purple

Question 28

– used for the detection of free amine on amino acids or peptides where ninhydrin reagent forms an intense violet colored complex called Ruhemann’s purple

Answer 28

Ninhidyrin test

Question 29

violet colored complex in ninhydrin test

Answer 29

Ruhemann's purple

Question 30

is a chemical test that can differentiate between an alpha-amino group and a free amino acid.

Answer 30

ninhydrin test

Question 31

In this test, ninhydrin is used as an oxidizing/reducing agent that reacts with the amino group of the analyte

Answer 31

oxidizing

Question 32

positive ninhydrin test is what color

Answer 32

purple-colored complex

Question 33

what is the color of ninhydrin when proline is present

Answer 33

yellow

Question 34

Proline is an _____ and it reacts with ninhydrin to form a yellow-colored complex

Answer 34

imino acid

Question 35

This is because the reaction of proline with ninhydrin yields an ___ salt, which is yellow-orange in colo

Answer 35

iminium

Question 35

used to distinguish the presence of tryptophan or tyrosine which forms yellow-colored product with nitric acid

Answer 35

Xanthoproteic test

Question 36

tryptophan or tyrosine forms a yellow-coloredp roduct with what reagent

Answer 36

nitric acid

Question 37

what structure of these amino acids reacts with nitric acid forming a yellow by-product

Answer 37

benzene ring

Question 38

used to confirm the presence of tyrosine by the formation of reddish-brown product with mercury in nitrous acid

Answer 38

Millons test

Question 39

reagent that tyrosine reacts with in Millons test

Answer 39

acificied mercuric sulphate solution

Question 40

Detects tyrosine by the reaction of its phenolic group with the reagents, producing a reddish-brown complex

Answer 40

millons test

Question 41

used for the detection of tryptophan which forms a violet ring upon reaction with glyoxylic acid and conc. Sulfuric acid

Answer 41

hopkins-cole test

Question 42

Detects tryptophan by the reaction of its indole ring reacts with the reagents

Answer 42

hopkins-cole test

Question 43

Manifested in the formation of violet ring in between the layer of the sample and sulfuric acid

Answer 43

positive hopkins-cole test

Question 44

reagent in Hopkins-cole test

Answer 44

glyoxylic acid

Question 45

disruption of these stabilizing forces and bonds in a protein that results to the disruption of its native conformation and subsequent loss of its biological function

Answer 45

denaturation

Question 46

Physical manifestations that can denature a protein

Answer 46

mechanical agitation heat

Question 47

Chemical agents that can denature a protein:

Answer 47

➢ Acids ➢ Bases ➢ Salts ➢ Organic solvents ➢ Detergent ➢ Alkaloids ➢ Heavy metals

Question 48

Chaotropic agents include (5)

Answer 48

– guanidine HCl urea, βmercaptoethanol, dithioeitol

Question 49

can disrupt specific stabilizing bonds or forces in the protein which leads to alternation in its structure as manifested by the precipitation of the protein from the solution

Answer 49

chaotropic agents

Question 50

Stabilizing bonds or force in proteins

Answer 50

H-bond Salt bridge Hydrophobic interaction disulfide bond

Question 51

Fill in the blanks Carefully separate egg white from yolk of one medium-sized chicken egg. Discard _____. Measure the volume of egg using a ______ . Transfer to a 250 ml beaker and dilute with equal volume of _____ ______. Use as a sample for subsequent analysis

Answer 51

yolk graduated cylinder phosphate buffer

Question 52

Transfer _____ mL of the egg white solution to _____separate test tubes and label them properly. Add the ff reagents to the respective test tubes:

Answer 52

2 mL 5 test tubes

Question 53

Test tube 1 – 2.00 ml of ____solution, heat for 5 minutes in water bath or until a color change is observed

Answer 53

ninhydrin solution

Question 54

test tube 2 – 5 drops of concentrated ___ _____ (xanthoproteic test), heat for 5 minutes in water bath or until a color change is observed

Answer 54

nitric acid

Question 55

Test tube 3 – 5 drops of ______ _____, heat for 5 minutes in water bath or until precipitate is formed

Answer 55

Millon's reagent

Question 56

Test tube 4 – 5 drops of _____ ____ (HopkinsCole reagent), tilt the tube slightly and carefully add 2.0 mlo of concentrated sulfuric acid to form two layers. Wait for color change

Answer 56

glyoxylic acid

Question 57

Test tube 5 – 2 mL of ______ solution and 1 mL of 0.200 M _____. Shake vigorously and incubate until a color change is observed

Answer 57

biuret NaOH

Question 58

Transfer 2 mL of the egg white solution to _ separate test tubes and label them properly. Add the following reagents to the respective test tubes

Answer 58

8

Question 59

Test tube 1 – 0.200 M ___ drop by drop until change occurs

Answer 59

HCl

Question 60

test tube 2 – 0.200 M ____ drop by drop until change occurs

Answer 60

NaOH

Question 61

Test tube 3 – 0.200 M _____ ____drop by drop until change occurs

Answer 61

lead acetate

Question 62

Test tube 4 – 0.200 M _____ drop by drop until change occurs

Answer 62

urea

Question 63

Test tube 5 – 0.200 M ____ acid drop by drop until change occurs

Answer 63

tannic

Question 64

test 6 – 70% ____ drop by drop until change occurs

Answer 64

ethanol

Question 65

Test tube 7 – _____in water bath until change occurs

Answer 65

heat

Question 66

Test tube 8 – ______ vigorously until change occurs

Answer 66

shake

Question 67

– increases kinetic energy, causing atoms of proteins to vibrate. The vibrating motion disrupts or breaks the weak hydrogen bonds and dispersion forces

Answer 67

heat

Question 68

The accelerated vibration can disrupt the _____ ______ , _______ ______, as well as ___ _____forces, causing the unfolding of protein’s 3D structure

Answer 68

hydrogen bond hydrophobic interactions van der waals

Question 69

a hydrogen bonds to polarized areas of charge, such as peptide groups.

Answer 69

urea

Question 70

Mutual influence weakens the intermolecular bonds and interactions, weakening the overall secondary and tertiary structure

Answer 70

urea

Question 71

capable of engaging in intermolecular hydrogen bonding with protein molecules, disrupting intramolecular hydrogen bonding within the protein

Answer 71

ethanol

Question 72

combine with positively charged amino groups in proteins to disrupt ionic bonds

Answer 72

tannic acid

Question 73

normally, a person hav

Answer 73

protein

Question 74

– large amount of protein in urine may mean that you have a problem with your kidneys

Answer 74

proteinuria

Question 75

Early sign of chronic kidney diseases (CKD

Answer 75

proteinuria

Question 76

Needed for the synthesis of proteins

Answer 76

phenylalanine

Question 77

Important precursor of amino acid Ltyrosine (Tyr)

Answer 77

phenyalanine

Question 78

Used as an energy fuel

Answer 78

phenylalanine

Question 79

too much of this when converted into phenylpyruvate, and the individual usually develops seizures, brain damage, and mental retardation

Answer 79

phenyalanine

Question 80

too little of this causes growth failure, loss of muscle mass, and organ damage

Answer 80

phenylalanine

Question 81

Play a significant role in the regulation of energy metabolism, locomotor activity, and eating behavior

Answer 81

tyrosine

Question 82

too much of this can cause migraine headaches and hyperthyroid conditions

Answer 82

tyrosine

Question 83

too little of this is associated with behavioral and learning disorders, depression, anxiety, and inability to deal with stress

Answer 83

tyrosine

Question 84

role in brain serotonin synthesis is an important factor involved in mood, behavior, and cognition

Answer 84

tryptophan

Question 85

high levels is associated with headaches and selective serotonin reuptake inhibitor treatmen

Answer 85

tryptophan

Question 86

Low levels are commonly correlated with depression, insomnia, and schizophrenia

Answer 86

tryptophan