Formation of Proteins in the Lab

Question 1

steps

Answer 1

protect aa f.g. then react c terminus

after 1st peptide bond formed, remove PG

add next n-terminus protected aa

Question 2

2 steps condensed

Answer 2

peptide bond formation

removal of PG

Question 3

method name

Answer 3

Merrifield solid-phase technique (automated)

Question 4

Merrifield info

Answer 4

solid phase x-linked PS beads (hydrophobic/insoluble)

solvated NP solvents (CH2Cl2, DMF)

x-linked with 1-2% divinyl benzene

functionalized linker

Question 5

Friedal Crafts rxn

Answer 5

PS-benzene ortho attacks CH2Cl2 with AlCl3’s help

then add peptide w/ protected N terminus (tboc)

Cl- leaves the CH2Cl2 and deprotonates new ester

Question 6

what to do with coupling agents?

Answer 6

must wash to remove coupling agents

remove the PG

couple–> wash –> deprotect repeat

Question 7

protecting groups

Answer 7

n-terminus t-boc + NaHCO3

c-terminus is bound to PS-benzene-CH2

side chains: benzyl, benzoyl, silyl ether

Question 8

deprotection of tboc

Answer 8

Hbr, CH3C=OOH, anhydrous

NH protonated by Hbr

T boc decomposes to v. stable CO2 + CH(CH3)3

Question 9

scavenger

Answer 9

C(CH3)3 cation reactive.. sometimes forms double bond

add scavenger to be sure ANISOLE

benzene with OCH3 at top

Question 10

last step

Answer 10

add PS-benzene-stuff-free NH2 + DCC with excess peptide with free c-terminus and protected N terminus