1. Amino acids Proof. Dr. Abdulhussien Aljebory College of pharmacy 2016 -2017

2.  Same general structure  Called alpha amino acids  L- isomer is physiologically active  Side chain or R group determines other properties  Acid-base properties Amino Acids:properties

3.  building blocks of proteins  form bonds with each other, resulting in a polypeptide chain  More than 300 different amino acids  Only 20 are found in mammalian proteins  Only 10 are essential amino acids

4.  general Structure  Alpha Carbon  Carboxylic acid group (COOH)  Amide group (NH2)  R-group  The R group (Residue group) is responsible for the unique properties of each amino acid

6.  At physiologic pH (pH 7.4) 1. the carboxyl group is dissociated, forming a negatively charged carboxylate ion -COOH  -COO - + H +

7. 2. The amide group is protonated -NH2 + H+  -NH3 +

11. 1 -Non-polar amino acids  Aliphatic  Aromatic 2. Polar-Uncharged amino acids 3. Acidic amino acids 4. Basic amino acids

13.  Similar to uncharged aliphatic groups  Have an aromatic ring (Benzyl ring)  Hydrophobic  Cluster in the interior of the protein

17.  Proton donors  Negatively charged at neutral pH

18.  Positively charged at neutral pH  Proton acceptors

19.  (Gly) Glycine – G  Alanine – A (Ala)  Valine – V (Val)  Leucine – L (Leu)  Methionine – M (Met)  Isoleucine – I (Ile)

20.  Phenylalanine – F (Phe)  Tyrosine – Y (Tyr)  Tryptophan – W (Trp)

21.  Serine – S(Ser)  Threonine – T(Thr)  Cysteine – C (Cys)  Proline – P (Pro)  Asparagine – N (Asn)  Glutamine – Q (Gln)

22.  Aspartate – D (Asp)  Glutamate – E (Glu)

23.  Lysine – K (Lys)  Arginine – R (Arg)  Histidine – H (His)

24. 24 Cysteine can form disulfide bridges

25. 25 Disulfide bridges can crosslink proteins. Disulfide bonds are broken by mercaptoethanol.

26.  All Amino acids are optically active, EXCEPT glycin  The alpha carbon is chiral  Can exist in the D form or L form  Mirror images  Almost all amino acids are L-type

28. “PVT TIM HALL” (Pro,Val,Thr, Try, Iul,Met, His, Arg, Leu, Lys) Proline, Valine, Threonine, Tryptophan, Isoleucine, Methionine Histidine, Arginine, Leucine, Lysine

29.  Amino acids in aqueous solution contain weakly acidic carbon groups and weakly basic amino groups  Both free a.a and some combined amino acids can potentially act as buffers

30.  A pH is defined as the negative logarithm of the hydrogen ion concentration. It is mathematically represented by the formula: pH= - log [H + ]

31.  Buffers stabilize a solution at a certain pH.  Henderson-Hasselbach equation pH= pKa + log __[A - ]____ [HA]  Correlation  HCO3/ H2CO3 buffer system