Amino-acizi naturali

Amino-acizi naturali

Amino-acizii sunt combinatii organice care contin in molecula una sau mai multe grupe amino si una sau mai multe grupe carboxil. Dupa structura, amino-acizii se impart in doua mari categorii:

1.      Alifatici: unde grupele functionale sunt legate de o catena alifatica, chiar daca in molecula exista un nucleu aromatic.

2.      Aromatici: unde grupele functionale sunt legate de un ciclu aromatic.

Dupa asezarea relativa a grupelor functionale se deosebesc α-amino-acizi, β-amino-acizi, γ-amino-acizi, etc. Dintre amino-acizii alifatici, cei mai importanti sunt α-amino-acizi, adica acei amino-acizi care contin grupele functionale legate de acelasi atom de carbon. Se deosebesc mai multe categorii mari de α-amino-acizi alifatici:

1.      monocarboxilici

2.      dicarboxilici

3.      hidroxi-amino-acizi

4.      tioamino-acizi

5.      diamino-acizi

6.      amino-acizi heterociclici

Denumirea

Prescurtarea

Formula

Amino-acizi  monocarboxilici

Leucina (acidul α-aminoizocapronic)	Leu	CH3—CH—CH2—CH—COOH                  |                    |                CH3                 NH2
Izoleucina (acidul α-amino-β-metilvalerianic)	Ileu	CH3—CH2—CH — CH—COOH                              |         |                            CH3      NH2
Fenilalanina (acidul α-amino-β-fenil-propionic)	Fe	—CH2—CH—COOH                                      |                                    NH2
Glicocolul(glicina) (acidul aminoacetic)	Gli	CH2— COOH        |      NH2
Alanina (acidul α-aminopropionic)	Ala	CH3—CH—COOH                   |                 NH2
Valina (acidul α-aminoizovalerianic)	Val	CH3—CH — CH—COOH                   |         |                 CH3       NH2

Amino-acizi dicarboxilici

Acidul asparagic (acidul aminosuccinic)	Asp	HOOC—CH2—CH—COOH                                     |                                   NH2
Acidul glutamic (acidul α-aminoglutaric)	Glu	HOOC—CH2— CH2—CH—COOH                                                |                                              NH2

 

Hidroxi-amino-acizi

Treonina (acidul α-amino-β-hidroxibutiric)	Tr	CH3—CH — CH—COOH                  |           |                 OH      NH2
Tirosina (acidul α-amino-β-hidroxifenil-propionic)	Ti	HO                    —CH2—CH—COOH                                                |                                              NH2
Serina (acidul α-amino-β-hidroxipropionic)	Ser	CH2 — CH—COOH        |         |       OH     NH2

Tio-amino-acizi

Cistina (acidul di[α-amino-β-tiopropionic] )	Ci—S Ci—S	HOOC—CH—CH2—S—S-- CH2—CH—COOH                       |                                           |                  NH2                                     NH2
Metionina (acidul α-amino-γ-metiltiobutiric)	Met	CH2— CH2—CH—COOH    |                     |     S -- CH3          NH2

Cisteina (acidul α-amino-β-tiopropionic)

Cis

CH2 — CH—COOH        |          |       SH      NH2

 

 

Diamino-acizi

Ornitina (acidul α, δ-diaminovalerianic)	Or		CH2— CH2—CH2—CH—COOH      |                                |    NH2                                        NH2
Lisina (acidul α, ε-diaminocapronic)		Lis	CH2— CH2—CH2—CH2—CH—COOH     |                                            |   NH2                                                         NH2

Amino-acizi heterociclici

Prolina (acidul pirolidin-α-carboxilic)	Pro	H2C— CH2                             |         |                          H2C      CH—COOH                              \       /                                 NH
Hidroxiprolina (acidul β-hidroxipirolidin-α-carboxilic)	Hipro	HO—HC — CH2                                |           |                         H2C      CH—COOH                             \       /                                NH
Histidina (acidul α-amino-β-imidazolil-(4)-propionic) (imidazolil-(4)-alanina)	His	N — C — CH2— CH—COOH          ||       ||                        |        HC     CH                NH2           \       /              NH
Triptofanul (acidul α-amino-β-indolil-(3)-propionic) (indolil-(3)-alanina)	Tri	— CH2— CH—COOH                                              |                                            NH2