Biochemistry > Chaoter 5: Proteins > Flashcards

Chaoter 5: Proteins Flashcards

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0
Q

Proteins that support cells and organisms

A

Structural proteins

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1
Q

Catalysts to aid in chemical Rx

A

Enzyme

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2
Q

Defensive proteins

A

Immune proteins

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3
Q

Proteins that carry molecules

A

Transport and storage proteins

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4
Q

Proteins that control cellular and physiological activities

A

Regulatory and receptor proteins

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5
Q

Proteins that act as functional components of the contractile system

A

Muscle contraction and mobility proteins

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6
Q

The molecular mass of proteins is quantified in units called ____. The conversion is _______.

A

Daltons. 1 Da = 1 amu

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7
Q

Made of a single polypeptide chain

A

Monomeric

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8
Q

Made of 2 or more polypeptide chains

A

Oligomeric

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9
Q

Peptide chains in a protein are called ____.

A

Subunits

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10
Q

The non protein portion of a protein. Ex) _____

A

Prosthetic group, heme -Fe group

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11
Q

Protein with a small organic molecule or metal atom

A

Conjugated

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12
Q

Water soluble protein

A

Globular

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13
Q

Water insoluble protein found in collagen and keratin

A

Fibrous

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14
Q

The final fold arrangement of the polypeptide chain in proteins

A

Conformation

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15
Q

What determines how proteins fold?

A

The hydrophobic groups minimize exposure to solvents.

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16
Q

Polypeptide chains are connected by _____ bonds.

A

Disulfide

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17
Q

What does ELISA stand for?

A

Enzyme-Linked ImmunoSorbent Assay

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18
Q

What is a sorbent?

A

Something absorbed on a surface

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19
Q

ELISA relies on ________ ________ of the antigen and antibody.

A

Binding competition

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20
Q

UV Absorbance Spectra detects proteins by using what law?

A

Beer Lambert

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21
Q

If a protein has a _______ that absorbs in the UV-VIS region of the spectrum, this absorbable can be used to ______.

A

Chromophore, assay

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22
Q

What do the variables stand for in A=ECl?

A

A - absorbance
E - molecular extinction coefficient
C - concentration of sample
l - path length of cell

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23
Q

The fluorescence wavelength of excitation is (greater than/less than) the fluorescence wavelength of emission?

A

Less than

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24
What two AA have the highest E?
Trp and Tyr
25
Coomassie brilliant blue dye must be added to the target protein in acidic conditions. Why?
So the negative charge of the dye will bind to the positive charge of the protons.
26
Bradford Assay has an absorbance of ____.
595 nm
27
In salting in, the solubility of a protein _____ as salt is added.
increase
28
In salting out, the solubility of a protein ____ as salt is added.
decrease
29
Why does the addition of salt affect the solubility of a protein?
competition between the added salt ions and the other dissolved solutes in the solvent
30
During ion exchange chromatography, proteins with opposite charge bind to the ____, or stationary phase.
resin
31
Gel filtration separates molecules by their ____.
size
32
T/F? The affinity column contains resin made of molecules that bind to the target protein.
True
33
PAGE separates molecules on a ________ gel matrix when what is applied?
polyacrylamide, electric field
34
SDS stands for?
Sodium dodecyl sulfate
35
In SDS-PAGE, what does SDS coat proteins with?
a negative charge
36
Salting out and in
solubility and charge
37
Ion exchange chromatography
charge
38
electrophoresis
charge
39
isoelectric focusing
charge
40
hydrophobic interaction chromatography
polarity
41
gel filtration
size
42
SDS-PAGE
size
43
affinity column
binding affinity
44
What happens to proteins under high salt concentrations?
form a precipitate
45
What salt is generally used in salting out?
ammonium sulfacte TCA
46
Salt precipitate is linked by what kind of interaction?
noncovalent
47
The mobile phase of ion exchange chromatography is a _______ that solubilizes proteins.
buffer
48
What method of protein purification utilizes charged beads?
ion exchange chromatography
49
What does DEAE stand for? What is its charge?
diethylaminoethyl, positive
50
What does CM stand for? What is its charge?
carboxylmethyl, negative
51
T/F? When DEAE is used, it is called cation exchange.
False, anion exchange
52
When DEAE is used, the first molecules to be eluted have what charge?
positive, then neutral
53
What method of protein purification utilizes porous beads?
Gel filtration
54
T/F? The stationary phase of gel filtration is a column of porous beads that are smaller than most of the proteins.
False, larger
55
In gel filtration, what size molecules will elute first and why?
large because they cannot enter the pores
56
Affinity chromatography utilizes binding interactions between what two things to isolate the target protein?
proteins and ligands
57
Many proteins contain ________ for substrates to bind to.
binding pockets
58
What information must you know before attempting affinity chromatography?
the pattern of binding pocket for target protein
59
PAGE stands for what?
PolyAcrylamide Gel Electrophoresis
60
T/F? There is no addition of chaotropic reagants in PAGE.
True
61
During PAGE, the ______ of a protein will differ due to their mass, shape, and charge.
electromobility
62
SDS-PAGE uses _____________ to reduce disulfide bonds.
mercaptoethanol HS-CH2-CH2-OH
63
T/F? SDS-PAGE denatures proteins and changes them all to positively charged.
False, negatively
64
The first dimension of electrophoresis is called __________.
isoelectric focusing
65
Describe the electromobility of a protien at its pI.
It stops moving.
66
The higher the densitiy of a species, the _______ the sedimentation coefficient.
higher
67
Ultracentrifugation is useful for what?
isolating cellular organelles
68
T/F? Proteins are most soluble at their pI.
False, least
69
Explain why a protein would have a high pI and how that would affect precipitation solution.
It has lots of basic aa residue. The solution would need to be basic.
70
What is necessary to sequence a protein?
It must first be cleaved into overlapping fragments.
71
The amino acid sequence of a protein can be determined by ______ ___________, a procedure for removing the N-terminal residues one at a time.
Edman degradation
72
Mass spec can identify amino acid sequences from the _________ ratio of desolvated protein fragments.
mass-to-charge
73
What are the two main enzymes used to digest a protein? What is the class of these enzymes?
trypsin and chyrotrypsin, endopeptidase
74
Which endopeptidase is specific for the C-terminus of positively charged, polar basic residues, such as R and K?
trypsin
75
Which endopeptidase is specific for the C-terminus of bulky, hydrophobic residues, such as F, W, and Y?
chyrotrypsin
76
T/F? Pepsin is nonspecific.
True
77
An unactivated precursor of an enzyme.
zymogen
78
Why is ESI necessary for Mass Spec?
only ions can be detected
79
What does ESI stand for?
Electro Spray Ionization
80
In Elisa, binding of the second antibody-enzyme complex is measured how?
By measuring the substrate conversion to product
81
Absorbance at 280 nm indicates a _______.
Protein
82
Absorbance at 260 nm indicates a ______.
Nucleic acid
83
An excited molecule emits a wavelength range of ______.
290-295 nm
84
A molecule that has not been excited emits a wavelength range of ____.
300-330 nm
85
What classification of amino acid will bind to coomassie brilliant blue? Why?
Polar basic because of extra amino group at phys pH
Biochemistry
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