Lecute 6 Flashcards
1
Q
How many naturally occurring amino acids
A
20
2
Q
How many naturally occurring amino acids have chiral carbons
A
19
(18 have s stereochemistry)
3
Q
2 functional groups on amino acids
A
- NH2
- COOH
4
Q
A b and y amino acids
A
- when -NH2 and -COOH groups on the same C
- a amino acids
- a means that the NH2 is o the carbon next to c=o
5
Q
All the amino acids expect glycine are
A
- chairal molecuels so exist as a part of enentomers
- they have a stereogenic centre
6
Q
3D arrangement of groups of amino acids
A
- all have the same 3D arrangement apart from cysteine
- all S configuration apart from cysteine
- Fischer projection is drawn with COOH at top
- L if NH2 is on left - all natural chiral amino acids exist in the L-form
7
Q
Side chains
A
- the difference between various amino acids
8
Q
Nature of side chains
A
9
Q
Chemistry of amino acids
A
- dictated by the functional groups
- NH2 is a nucleophiles and a base
- COOH acid, nucleophillic substitution
- any additional functionality in the side chain
- a carboxylic acid is a weak acid and an amine is a weak base!!!!!!!!!
- the fact these two groups are in close proximity imparts properties on the a-amino acids
10
Q
The PI is…
A
An important structural parameter as it influences a molecules solubility and its electro mobility in analytic techniques such as electrophoresis
11
Q
Electrophoresis
A
- separation/ analytical technique that discriminates molecules on their electro mobility and thus overall charge
12
Q
Amino acids in ther charged form dominates rather then non-ionic form
A
