Protein Techniques

Question 1

what is the size of proteins?

Answer 1

~ 50 - 8000 aa

Question 2

how do you calculate the MW of a protein?

Answer 2

MW = # of aa x 110

Question 3

conjugated proteins contain…?

Answer 3

prosthetic groups

Question 4

what type of proteins contain lipid?

Answer 4

lipoproteins

Question 5

what type of proteins contain carbohydrates?

Answer 5

glycoproteins?

Question 6

what type of proteins contain metals?

Answer 6

metalloproteins

Question 7

what type of proteins contain flavin?

Answer 7

flavoproteins

Question 8

what type of proteins contain phosphate?

Answer 8

phosphoproteins

Question 9

lambert-beer law

Answer 9

absorbance (A) = log (Io) / I = Ecl

Question 10

what is the lambert-beer law used for?

Answer 10

to quantify how much protein is in a solution

Question 11

how does the lambert-beer law quantify protein?

Answer 11

• relies on the absorbance of aromatic aa

- Try & Trp absorb light at 280 nm

Question 12

which aa absorb light?

Answer 12

aromatic ones

Question 13

how do FDNB, Ninhydrin, Fluorescamine, & Dandsyl chloride; Dabsyl chloride quantify protein?

Answer 13

• protein reacts with the chemical reagent that binds to free amine groups
• these reagents contain large ring structures that absorb light, and thus enhance sensitivity of absorbance measurements

Question 14

1) ion exchange chromatography
2) what determines net charge?
3) anion exchange
4) cation exchange

Answer 14

1) separates proteins on the basis of electric charge
2) pH determines net charge
3) cation exchange: resin has fixed cationic (+) groups (binds anions); proteins with a more negative net charge move faster and elude earlier
4) anion exchange: resin has a fixed anion (-) groups (binds cations)

Question 15

affinity chromatography separates protein based on…?

Answer 15

binding specificity; purified protein is released by addition of ligand

Question 16

molecular sieve chromatography separates protein based on…?

Answer 16

size; small proteins are trapped in beads and move slowly while bigger proteins come out first b/c can’t enter the beads

Question 17

gel electrophoresis separates protein based on…?

Answer 17

size; in electrical field, proteins will migrate toward anode (+ pole) at rate inversely ∞ to log MW

Question 18

Isoelectric Focusing separates protein based on…?

Answer 18

pI; proteins migrate to area at which their overall charge is neutral

Question 19

2D gel electrophoresis

Answer 19

• 1st dimension: isoelectric focusing

- 2nd dimension: SDS-PAGE

Question 20

IM TIRED AND DONT FEEL LIKE DOING ANYMORE OF THESE!!!!

Answer 20

:)~