Dr/ Ragaa Salama1 1 Amino acids Objectives Define amino acids. Describe the chemical nature of amino acids. list the essential, semi-essential, non essential. list the glucogenic, ketogenic & mixed (glucogenic & ketogenic) ones.

Dr/ Ragaa Salama2 General Structure of Amino Acid Structure Amino end Acid End Side chain Zwitterion Form pH = 7.0

Dr/ Ragaa Salama3 3 Amino acids pool & peptide bond

Dr/ Ragaa Salama4 4 Definition and Importance of proteins Definition of proteins: - organic compounds with a high molecular weight. - polymers α-amino acids linked together by peptide bonds. Definition of amino acids: -building units of body proteins. -Formed of carbon+ oxygen + hydrogen + nitrogen ± sulfur ± phosphorus. -Only 20 aa coded by DNA.

Dr/ Ragaa Salama5 Classification of aa 1- Chemical classification: Based upon the number of amino groups or carboxyl groups in the amino acid: - Neutral aa → mono-amino, mono-carboxylic. - Acidic aa → mono-amino, dicarboxylic. - Basic aa → diamino, mono-carboxylic

Dr/ Ragaa Salama6 Neutral amino acids - They contain one amino group and one carboxyl group. They have 5 types: 1-Aliphatic amino acids:

Dr/ Ragaa Salama7 2-Hydroxy amino acids contain – OH group in their side chain e.g., serine, threonine, tyrosine, hydroxyproline and hydroxy-lysine. -Serine →choline for phospholipid and acetylcholine synthesis -OH groups of threonine and serine → protein glycosylation and phosphorylation.

Dr/ Ragaa Salama8 3. Aromatic amino acids phenylalanine, tyrosine and tryptophan. -Tyrosine is synthesized from phenyl alanine - both give triiodothyronine (T3) and thyroxin(T4), adrenaline and noradrenaline, melanin pigment

Dr/ Ragaa Salama9 4-Sulfur-containing amino acids -Cysteine gives cystine and its SH group → the active sites of enzymes. -important for intra- and inter-polypeptide disulfide bond formation that stabilizes protein structure. - S-adenosylmethionine is active form of methionine and is the main methyl donor.

Dr/ Ragaa Salama10 5-Heterocyclic amino acids -Histidine → histamine -Tryptophan → nicotinic acid, melatonin, serotonin -Proline → hydroxyproline → essential for collagen structure, called imino acids

Dr/ Ragaa Salama11 Acidic amino acids - 2 carboxyl groups and one amino group, e.g., glutamic acid and asparatic acid. -Glutamine has a major role in removing ammonia from the brain -- Glutamic acid is a neurotransmitter and essential for urea and glutathione synthesis. Asparagine → glycosylation.

Dr/ Ragaa Salama12 Basic amino acids -contain 2 amino groups and one carboxyl group, e.g., Ornithine, Arginine and Citrulline → urea synthesis from ammonia. -Arginine → nitric oxide. - Ornithine → polyamines that are important for cell cycle control. -Lysine and Hydroxy lysine → collagen structure

Dr/ Ragaa SalamaDr/ Ragaa Salama 13Dr/ Ragaa Salama13 2-Biological or Nutritional Classification A- Essential aa :- aa can not be synthesized in the human body and should be taken in the diet deficiency → a nutrition deficiency disease → affect both growth and health. The main source for these amino acids are animal proteins (milk, egg, meat, liver, fish, chicken) and a few plant proteins (bean and lintels). They are as follows (VITTAL LyMPH): B- semi-essential aa: Arginine and histidine they are mainly required in growing children, pregnant, lactating women and convalescent patients. C- Non essential amino acids: - The rest of aa can be synthesized inside the human body and their deficiency in diet does not affect the growth or the health ValineIsoleucineThreonineTryptophanArginine LeucineLysineMethioninePhenylalanineHistidine.

Dr/ Ragaa SalamaDr/ Ragaa Salama 14Dr/ Ragaa Salama14 3-Metabolic Classification KetogenicKetogenic & glucogenic Glucogenic LeucineLysineRest of amino acids Isoleucine Tyrosine Tryptophan Phenyl alanine Based upon the fate of aa inside the body: - Glucogenic amino acids, → converted to glucose. - Ketogenic amino acids → converted to ketone bodies. Mixed amino acids, → both glucose and ketone bodies