Amino Acids

Question 1

What are the methods of amino acid synthesis?

Answer 1

The Strecker Synthesis

Hell-Vollhardt Zelinski reaction

both methods produce racemic mixtures unless chiral auxiliary is used
- racemates would require resolution to obtain optically pure amino acids

Question 2

What is required for the Strecker Synthesis to take place?

Answer 2

a source of ammonia
- could be from ammonium chloride

a source of cyanide ion
- could be from sodium cyanide

an aldehyde

Question 3

What is the Strecker Synthesis?

Answer 3

reaction involves the reaction of a cyanide ion with an imminium ion

Question 4

What can be done to ensure that Strecker Synthesis produces enantiomerically enriched products?

Answer 4

a chiral auxilliary approach can be used
- the one face of the imine is blocked by a large bulky group, forcing the reaction to take place on the other face of the imine
= ensuring one product predominates.

Question 5

What is the Hell-Vollhardt Zelinski reaction?

Answer 5

involves the alpha bromination of a carboxylic acid followed by displacement of the halogen by ammmonia

Question 6

What is required for Hell-Vollhardt Zelinski reaction?

Answer 6

carboxylic acid
brominne - halogen
phosphorous tribromide - catalyst
water

Question 7

How can racemic amino acids be resolved via enzyme resolution?

Answer 7

1 - N-acylation using acetic anhydride
= acetic anhydride has duel role in acetylating NH2 and protecting the amino group
2 - treat the mixture with enzyme carboxypeptidase
= removes the acyl group from only the S isomer which is water soluble. it allows the insoluble R isomer to isolated

Question 8

What is glutathione? What is its role?

Answer 8

is a tripeptide present in nearly all the tissues of the body

role is in detoxification
- removes dangerous oxidising agents from the body
= has a nucleophilic SH group which detoxes toxins by reacting with electrophiles

Question 9

How does glutathione detoxify paracetamol?

Answer 9

under normal usage paracetamol is metabolised to an hydroxylamine prior to excretion
- is unstable

glutathione reacts with the unstable hydroxyl amine to form a state derivative
- can be safely excreted

Question 10

How is glutathione incorporated into tablet formulation ?

Answer 10

is incorporated as

• acetylcystein
• methionine

are precursors to glutathione