Organic Chemistry

Section 23.1 Classification and Nomenclature of Amino Acids 961

Sulfur-containing

amino acids

Cysteine Cys C 2.8%

Methionine* Met M 1.7%

Acidic amino acids Aspartate Asp D 5.5%

(aspartic acid)

Glutamate Glu E 6.2%

(glutamic acid)

Amides of acidic

amino acids

Asparagine Asn N 4.4%

Glutamine Gln Q 3.9%

Basic amino acids Lysine* Lys K 7.0%

Arginine* Arg R 4.7%

Benzene-containing

amino acids

Phenylalanine* Phe F 3.5%

Tyrosine Tyr Y 3.5%

Heterocylic

amino acids

Proline Pro P 4.6%

*Essential amino acids

O

CO−

N

Η Η

+

+NH

3

O

HO CH 2 CHCO−

+NH

3

O

CH 2 CHCO−

+NH

3

O

CHCO−

NH 2

H 2 NCNHCH 2 CH 2 CH 2

+

+NH

3

O

H 3 NCH 2 CH 2 CH 2 CH 2 CHCO−

+

+NH

3

O O

H 2 NCCH 2 CH 2 CHCO−

+NH

3

O O

H 2 NCCH 2 CHCO−

+NH

3

−OCCH 2 CH 2 CHCO−

O O

O O

+NH

3

−OCCH 2 CHCO−

O

+NH

3

CH 3 SCH 2 CH 2 CHCO−

O

+NH

3

HSCH 2 CHCO−

Average relative

abundance

Formula Name Abbreviations in proteins

Table 23.1 (continued)

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