Aminoacizii naturali

Categoria: Referat Chimie

Descriere:
Aminoacizii 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.

Aminoacizii naturali

Aminoacizii 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