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13. CARBOXYLIC ACIDS eLearn.Punjab

For example, the simplest amino acid is glycine H2NCH2 COOH. It may be
abbreviated as Gly. Similarly, alanine CH3 CH COOH may be represented as Ala.

NH2

Names, structural formulae and other features of some amino acids are given in
Table 13.2.

Table 13.2 Names, structural formulae and other features

of amino acids

Name Nature Abbreviation Structural formula

1 Glycine Neutral Gly CH2 COOH
2 Alanine Neutral Ala NH2
3 Valine Neutral Val CH3 CH COOH
4 Proline Neutral Pro NH2
CH3 CH CH COOH
CH3 NH2
H2C CH2
H2C CHCOOH
NH

5 Aspartic acid Acidic Asp HOOC CH2 CH COOH
Gla
Lys NH2
His
6 Glutamic acid Acidic HOOC CH2 CH2 CH COOH

NH2

7 Lysine Basic CH2 (CH2)3 CH COOH

NH2 NH2

8 Histidine Basic CH = C CH2 CH COOH

N NH NH2

CH

13.8.3 Structure of Amino Acids

The amino acids exist as dipolar ion called Zwitter ion. It has positive
as well as negative ends within the same molecule. In the formation
of Zwitter ion, the proton goes from the carboxyl group to amino
group. The Zwitter ionic structure of an amino acid may be written as:

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