Amino Acids (1) IUA, 2012

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Amino Acids (1)Atif H. Khirelsied, Ph.D.   Atif H. Khirelsied, Ph.D.Department of BiochemistryFaculty of MedicineInternational University of Africa, Khartoum, SudanAmino Acids1. Amino acids (aa) are organic acids with an amine Amino acids (aa) are organic acids with an amine group.  2. They are the "building blocks" of proteins. 3. Have a wide range of diverse biological functions. 4. There are more than 300 in nature. 4 There are more than 300 aa in nature 5. Only 20 L‐α‐amino acids ar

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AminoAcids(1)AtifH.Khirelsied,Ph.D. Atif H. Khirelsied, Ph.D.DepartmentofBiochemistry

FacultyofMedicineInternationalUniversityofAfrica,Khartoum,Sudan

AminoAcids1. Amino acids (aa) are organic acids with an amine Aminoacids(aa)areorganicacidswithanamine group. 2. Theyarethe"buildingblocks"ofproteins. 3. Haveawiderangeofdiversebiologicalfunctions. 4. Therearemorethan300 innature. 4 There are more than 300 aa in nature 5. Only20Laminoacids arefoundinproteins.Atif Hassan Khirelsied

AminoAcids5. DAminoacidsoccurinbacteriaandpeptide antibiotics. ibi i 6. Severalotheraminoacidsarefoundinnonprotein 6 S l h i id f di i substances.

Atif Hassan Khirelsied

AminoAcidsStructure

Atypicalaminoacidhasaprimaryaminogroup,acarboxyl group,ahydrogenatomandasidechain (Rgroup)attachedtoa chiral carbon atom carbonatom.

Atif Hassan Khirelsied

AminoAcidsStructure

TheFunctionsofAminoAcids Theyarethe"buildingblocks"ofproteins. y g p Are important (essential) nutrients Areimportant(essential)nutrients. Componentsofvariousbiomoleculese.g.,serinein phospholipids.

Atif Hassan Khirelsied

TheFunctionsofAminoAcids Precursor for various biologic substances Precursorforvariousbiologicsubstances. Glucose. Heme. Purines andpyrimidines. Neurotransmitters. Hormones

Atif Hassan Khirelsied

Aminoacids,isomerism &opticalactivity

Enantiomers

Allstandardaminoacidsexceptglycine andproline havechiral carbons(theC),thusexistinpairsof(D)and(L)enantiomers.

Atif Hassan Khirelsied

Aminoacidsclassifications Aminoacidscanbeclassifiedaccordingto: 1. 1 ChemicalnatureofRgroups Chemical nature of R groups 2. Solubility 3. Dietaryimportance 4. Metabolicfate

Atif Hassan Khirelsied

Aminoacids;classificationbyR-group According to the chemical nature of the side chain, Accordingtothechemicalnatureofthesidechain, aminoacidscanbeclassifiedinto:1. 1 2. 3. 3 4. 5. 6. 7. Aliphaticnonpolaraminoacids. Aliphatic nonpolar amino acids Sulfurcontainingaminoacids. Hydroxylcontainingaminoacids. H d l t i i i id Aromaticaminoacids. Acidicaminoacidsandtheiramides. Basicaminoacids. Imino acid

Atif Hassan Khirelsied

Thealiphaticnonpolaraminoacids

This class include: 1. 1 Glycine 2. Alanine 3. Valine 4. Leucine 5. Isoleucine

Atif Hassan Khirelsied

Thealiphaticnonpolaraminoacids1. 1 Glycine (Gly or G).Glycine

Is the smallest amino acid. p Has the simplest structure. Does not exist as a pair of stereoisomers

Atif Hassan Khirelsied

Thealiphaticnonpolaraminoacids2. 2 Alanine ( (Ala or A) )Alanine

Is aliphatic amino acid. Has a methyl group in the side-chain position.

Hydrophobic.Atif Hassan Khirelsied

Thealiphaticnonpolaraminoacids3. Valine, Val , (V).

4. Leucine, 4 Leucine Leu, (L).

5. Isoleucine, Ile, (I).Atif Hassan Khirelsied

Thealiphaticnonpolaraminoacids6.Methionine, Met, (M).

NOTEThealiphaticsidechainsofAla,Val,Leu,Ile&Metare nonreactive,hydrophobic.

Atif Hassan Khirelsied

Thesulphur containingaminoacids7. Cysteine Cys, (C).

Methionine Met (M)

Note Met is also an aliphatic non-polar amino acidAtif Hassan Khirelsied

Thehydroxylcontainingaminoacids8. Serine Ser, (S).

9. Threonine Thr, (T).

Tyrosine T i Tyr, (Y).Atif Hassan Khirelsied

Theacidicaminoacidsandtheiramides10. Aspartic acid Asp,(D)

11. Asparagine Asn, (N).

Atif Hassan Khirelsied

Theacidicaminoacidsandtheiramides

12.Glutamic acid Glu, (E).

13. Glutamine 13 Gl t i Gln, (Q).

Atif Hassan Khirelsied

Thebasicaminoacids14. 14 Araginine Arg, (R).

15. Lysine Lys, (K).

16.Histidine His, (H). His (H)Atif Hassan Khirelsied

Thearomaticaminoacids17. Phenylalanine Phe, (F).

18. 18 Tyrosine Tyr, (Y).

19. 19 Tryptophan Trp, (W).Atif Hassan Khirelsied

Theimino acid

20. Proline Pro, (P).

Thenitrogenatomissecondarilyattachedtotheside chains. chains

Atif Hassan Khirelsied

Thecystine

Atif Hassan Khirelsied

Aminoacidsclassificationbysolubility Twoclassesofaminoacidsbaseduponwhetherthe R groupis; Rgroup is; 1. Hydrophobic 1 H d h bi 2. Hydrophilic.

Atif Hassan Khirelsied

Aminoacidclassificationbydietary importance.Someaminoacidscanbeformedfrommetabolic intermediatesinthemammaliancells,thusarenot intermediates in the mammalian cells thus are not necessarytakeninfood(Dietarynonessential) .

Otheraminoacidsmustbeobtainedfromdiet,thus theyaretermed(Dietaryessential).Atif Hassan Khirelsied

AminoacidsclassificationbymetabolicfateAminoacidscanalsobeclassifiedaccordingtothe endproductoftheircarbonskeletoncatabolisminto: p 1. 1 Gluogenic glucose producing glucoseproducing 2. Ketogenic ketones producing 3. Keto andglycogenic.

Atif Hassan Khirelsied