Why We need to study About this?Protein Engineering.Structural Engineering.Growth of body.Major component of bodyCuring Different Diseases.
What is Amino Acid?• Amino acids are derivatives of carboxylic acidsformed by substitution of -hydrogen for aminofunctional group
What is Protein?The word protein came from a Greek word “Proteios”Proteins are like long necklaces with differentlyshaped beads. Each "bead" is a small moleculecalled an amino acid.Compounds composed of carbon, hydrogen, oxygen, andnitrogen and arranged as strands of amino acids
Protein Deficiency and Excess• Protein-deficiency symptoms are alwaysobserved when either protein or energy isdeficient• Extreme food energy deficiency is marasmus• Extreme protein deficiency is kwashiorkor• The two diseases overlap most of the timeand together are called PEM
Protein Deficiency and Excess• Protein-energy malnutrition (PEM)– World’s most widespread malnutrition problem– Includes both marasmus and kwashiorkor andstates of overlap• Hunger– Physiological craving for food– Progressive discomfort, illness, and pain resultingfrom the lack of food
What do Amino Acids Do?Amino acids are essential to life, have a role inmetabolism, and are important in nutrition.They form short polymer chains called peptides, aswell as longer chains that are called polypeptides orproteins.About 75 percent of the human body is made up ofchains of amino acids, which is why they are so vitalto how your system functions.All the chemical reactions that occur in the bodydepend on amino acids and the proteins they build.
Types of Amino AcidsAmino acids are classified as• Nonpolar (hydrophobic)with hydrocarbon sidechains.• Polar (hydrophilic) withpolar or ionic side chains.• Acidic (hydrophilic) withacidic side chains.• Basic (hydrophilic) with–NH2 side chains.Nonpolar PolarAcidic Basic
Metabolism of -amino acids
The Structure of Proteins• Side chain– The unique chemical structure attached to the backboneof each amino acid that differentiates one amino acidfrom another• Essential amino acids– Amino acids that either cannot be synthesized at all bythe body or cannot be synthesized in amounts sufficientto meet physiological needs
The Structure of Proteins• Conditionally essential amino acid– Amino acid that is normally nonessential, but must besupplied by the diet in special circumstances when theneed for it exceeds the body’s ability to produce it• Peptide bond– Bond that connects one amino acid with another, forminga link in a protein chain• Amino acids link into long strands that coil and foldto make a wide variety of different proteins
Peptide Linkages• Two dipeptides can result from reaction between A and S, depending on which COOH reactswith which NH2 we get AS or SA• The long, repetitive sequence of N CH CO atoms that make up a continuous chain iscalled the protein’s backbone• Peptides are always written with the N-terminal amino acid (the one with the free NH2group) on the left and the C-terminal amino acid (the one with the free CO2H group) onthe right• Alanylserine is abbreviated Ala-Ser (or A-S), and serylalanine is abbreviated Ser-Ala (or S-A)
Peptides and Proteins• Proteins and peptides are amino acid polymers in which theindividual amino acid units, called residues, are linked together byamide bonds, or peptide bonds• An amino group from one residue forms an amide bond with thecarboxyl of a second residue
Protein Types Based on Structure• The primary structure of a protein is simply the amino acid sequence.• The secondary structure of a protein describes how segments of thepeptide backbone orient into a regular pattern.• The tertiary structure describes how the entire protein molecule coilsinto an overall three-dimensional shape.• The quaternary structure describes how different protein moleculescome together to yield large aggregate structures
-Helix• -helix stabilized by H-bonds between amide N–Hgroups and C=O groups four residues away -helicalsegments in their chains
Secondary Structure: Triple HelixA triple helix• Consists of three alphahelix chains woventogether.• Contains large amountsglycine, proline, hydroxyproline, and hydroxylysinethat contain –OH groupsfor hydrogen bonding.• Is found in collagen,connective tissue, skin,tendons, and cartilage.
-Pleated Sheet• -pleated sheet secondary structure is exhibited by polypeptidechains lined up in a parallel arrangement, and held together byhydrogen bonds between chains
Denaturation of Proteins• The tertiary structure of a globular protein is the result of many intramolecularattractions that can be disrupted by a change of the environment, causing theprotein to become denatured• Solubility is drastically decreased as in heating egg white, where the albuminsunfold and coagulate• Enzymes also lose all catalytic activity when denatured