Sasse - Amino Acids, Peptides, Proteins 1 (TBC!!!!!!!)

3 methods of amino acid synthesis

hell volhard zelinsky

gabriel synthesis

strecker synthesis

hell volhard zelinsky

bromination followed by amination convert carboxylic acids into 2- amino acids

steps in hell-volhard zelinsky

bromine introduced

easily substituted by SN2 reaction

bromine is a good leaving group and is replaced with amino group

disadvantages

low yield

get enantiomers - not sterospecific

gabriel synthesis

-An amino acid is generated from phthalimide (nucleophile) and diethyl bromomalonate

gabriel synthesis - formation of versatile intermediate

hydrolyse (ester -> carbox acid)

decarboxylate

hydrolyse - nitrogen of amide is hydrolysed

gabriel synthesis - synthesis of amino acid form 2-propanedioate

deprotonation

alkylation

hydrolysis and decarboxylation

strecker synthesis

amino acids are prepared from aldehydes in the presence of ammonia or ammonium cyanide

strecker synthesis steps

start with aldehyde

carbonyl group -> amino grp via reductive amination

ammonium cyanide reacts with aminopropantrile

aminopropantrile

v versatile

can boil in slightly acidic aqueous solution and CN -> carbox acid -> amino acid

fermentation

production process in which a specific amino acid is synthesized in large amounts by a specially selected microorganism in culture

process of fermentation

selected microorganism is cultured with carbs + ammonia

cell produces glutamate from 2-oxo-glutaration by reductive ammonia fixation

what is the product of fermentation

selective release of the L form of the amino acid into the culture medium

discuss the bacteria used in fermentation

coryneform bacteria

-> gram pos, non-spore forming, non-motile, require biotin for growth

stereochemistry of natural amino acids

L configured and S enantiomers

L configured

in a fisher projection

- COOH on top

- NH2 on the left

- R on the bottom

what are two exceptions in the natural stereochemistry of amino acids

glycine - carbon is not chiral so no L or S just glycine

cysteine - have a sulfar so it is an L cysteine with R configuration

what is the resolution of amino acids

separating out the two enantiomers or to enrich the samples with S configuration and get rid of R