Amino Acid PDF

Ministry of Higher Education& Scientific research Alkunooze University College Dentistry Department Amino Acid By Dr. Mohammad Falih PhD. Clinical Biochemistry Contents 1- What are amino acid? 2- Structure of amino acid. 3- Clarif...

Ministry of Higher Education& Scientific research Alkunooze University College Dentistry Department Amino Acid By Dr. Mohammad Falih PhD. Clinical Biochemistry Contents 1- What are amino acid? 2- Structure of amino acid. 3- Clarification of amino acid. 4- Function of amino acid. AMINO ACID: STRUCTURE AND CLASSIFICATION. Amino Acids organic molecules and building units of proteins. There are about 300 amino acids occur in nature. Only 20 of them enter in proteins synthesis. Structure of amino acids: Four different groups are attached to α- carbon: 1-Amino group 2- COOH group 3- Hydrogen atom 4- side Chain (R). Introduction Structure of amino acid There are twenty (20) different naturally occurring amino acids Classification of amino acids into Essential and nonessential amino acids  Essential amino acids: are amino acids which are not synthetized by the body and must be obtained by the diet.  Nine essential amino acids, including:  phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, leucine, and lysine.  Non essential amino acids : The human body can synthesize these amino acids using only the essential amino acids.  11 of the 20 amino acids are non-essential  Classification of Amino Acids  Amino acids are classified into three groups: 1. Neutral amino acids: are the largest group which are divided into:  Aliphatic amino acids ( glycine, valine, alanine, leucine, isoleucine).  Aromatic amino acids ( tyrosine, phenylalanine).  Heterocyclic amino acids ( tryptophan, histidine).  Sulpher containing amino acid (cysteine , methionine ) 2. Acidic amino acids ( aspartic acid , glutamic acid ) 3. Basic amino acids (Lysine , arginine).  Classification of Amino Acids: Classification according to polarity of side chain (R): A- Polar amino acid Amino acids classified as polar when R hydrophilic group so can forms hydrogen bond with H2O. In those amino acids, R may contain: * OH group : as in serine, threonine and tyrosine * SH group : as in cysteine * amide group: as in glutamine and aspargine * NH2 group or nitrogen act as a base (basic amino acids ): as lysine, arginine and histidine * COOH group (acidic amino acids): as aspartic and glutamic. B- Non polar amino acids Amino acids classified as non polar when R is alkyl hydrophobic group which can’t enter in hydrogen bond formation. 9 amino acids are non-polar ( glycine, alanine, valine, leucine, isoleucine, phenyl alanine, tryptophan, proline and methionine). Functions of Amino Acids Apart from being the monomeric constituents of proteins and peptides, amino acids serve variety of functions. ❶Some amino acids are converted to carbohydrates and are called as glucogenic amino acids. ❷Specific amino acids give rise to specialized products, e.g.  Tyrsione forms hormones such as thyroid hormones, (T3, T4), epinephrine and norepinephrine  Tryptophan can synthesise a vitamin called niacin.  Glycine, arginine and methionine synthesise creatine.  Glycine and cysteine help in synthesis of Bile salts.  Glutamate, cysteine and glycine synthesis glutathione.  Histidine changes to histamine on decarboxylation.  Serotonin is formed from tryptophan.  Glycine is used for the synthesis of haem..