Biochemistry Ch 3. Nonenzymatic Protein Function and Analysis

Question 1

Structural proteins

Answer 1

Compose the cytoskeleton, anchoring proteins, and much of the extracellular matrix, generally fibrous in nature

Question 2

Common structural proteins

Answer 2

Collagen, elastin, keratin, actin, and tubulin

Question 3

Motor proteins

Answer 3

Have one or more heads capable of force generation through a conformational change, have catalytic activity acting as ATPases to power movement, common applications include muscle contraction, vesicles movement within cells, and cell motility

Question 4

Common motor proteins

Answer 4

Myosin, kinesin, dynein

Question 5

Binding proteins

Answer 5

Bind a specific substrate, either to sequester it in the body or hold its concentration at steady state

Question 6

Cell adhesion molecules (CAM)

Answer 6

Allow cells to bind to other cells or surfaces

Question 7

Cadherins

Answer 7

Calcium dependent glycoproteins that hold similar cells together

Question 8

Integrins

Answer 8

Have two membrane spanning chains and permit cells to adhere to proteins in the extracellular matrix, some have signaling capabilities

Question 9

Selectins

Answer 9

Allow cells to adhere to carbohydrates on the surfaces of other cells and are most commonly used in the immune system

Question 10

Antibodies

Answer 10

aka immunoglobulins (Ig), are used in the immune system to target a specific antigen, contain a constant region and a variable region (responsible for antigen binding), formed of two identical heavy chains and two identical light chains, held together by disulfide linkages and non covalent interactions

Question 11

Antigen

Answer 11

Protein on the surface of a pathogen (invading organism) or a toxin

Question 12

Ion channels

Answer 12

Can be used for regulating ion flow into or out of a cell, three main types of ion channels

Question 13

Ungated channels

Answer 13

Always open

Question 14

Voltage gated channels

Answer 14

Open within a range of membrane potentials

Question 15

Ligand gated channels

Answer 15

Open in the presence of a specific binding substance, usually a hormone or neurotransmitter

Question 16

Enzyme linked receptors

Answer 16

Participate in cell signaling through extracellular ligand binding and initiation of second messenger cascades

Question 17

G protein coupled receptors

Answer 17

Have a membrane bound protein associated with a trimeric G protein, also initiate second messenger systems

Question 18

G protein coupled receptor steps

Answer 18

Ligand binding engages the G protein, GDP is replaced with GTP, the Alpha subunit dissociates from the beta and gamma subunits, the activated alpha subunit alters the activity of adenylate cyclase or phospholipase C, GTP is dephosphorylated to GDP, the alpha subunit rebinds to the beta and gamma subunit

Question 19

G protein

Answer 19

-

Question 20

Adenylate cyclase

Answer 20

=

Question 21

Phosphorlipase C

Answer 21

-

Question 22

Electrophoresis

Answer 22

Uses a gel matrix to observe the migration of proteins in response to an electric field

Question 23

Native PAGE

Answer 23

Maintains the proteins shape, but results are difficult to compare because the mass to charge ratio differs for each protein

Question 24

SDS PAGE

Answer 24

Denatures the proteins and maksthe native charge so that the comparison of size is more accurate, but the functional protein cannot be recaptured from the gel

Question 25

Isoelectric focusing

Answer 25

Separates proteins by their isoelectric point (pI), the protein migrations toward the electrode until it reaches a region of the gel where pH=pI of the protein

Question 26

Chromatography

Answer 26

Separates protein mixtures on the bases of their affinity for a stationary phase or a mobile phase

Question 27

Stationer phase

Answer 27

-

Question 28

Mobile phase

Answer 28

-

Question 29

Isoelectric point

Answer 29

-

Question 30

Column chromatography

Answer 30

Uses beads of a polar compound, like silica or alumina (stationary phase), with a nonpolar solvent (mobile phase)

Question 31

Ion exchange chromatography

Answer 31

Uses a charge column and a variably saline eluent

Question 32

Size exclusion chromatography

Answer 32

Relies on porous beads, larger molecules elute first because they are not trapped in the small pores

Question 33

Affinity chromatography

Answer 33

Uses a bond receptor or ligand and an fluent with free ligand or a receptor for the protein of interest

Question 34

X-ray crystallography

Answer 34

Can be used after the protein is isolated to determine protein structure

Question 35

Edman degradation

Answer 35

Sequential degradation that allows amino acid sequencing

Question 36

Analyzing protein structure

Answer 36

X-ray crystallography or NMR

Question 37

Analyzing amino acid composition

Answer 37

Simple hydrolysis

Question 38

Analyzing amino acid sequence

Answer 38

Edman degradation

Question 39

Analyzing activity levels for enzymatic samples

Answer 39

Determined by following the process of a known reaction, often accompanied by a color change

Question 40

Analyzing protein concentration

Answer 40

Can be determined colorimetrically, either by UV spectroscopy or through a color change reaction

Question 41

BCA assay, Lowry reagent assay, Bradford protein assay

Answer 41

Each test for protein and have different advantages and disadvantages, Bradford protein assay uses a color change from brown-green to blue and is the most common