PowerPoint Presentation On Proteins

PPT On Proteins

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Proteins Presentation Transcript:

1. Proteins- Introduction
The word protein comes from the Greek ("prota"), meaning "of primary importance" and these molecules were first described and named by the Swedish chemist Jöns Jakob Berzelius in 1838. However, proteins' central role in living organisms was not fully appreciated until 1926, when James B. Sumner showed that the enzyme urease was a protein. The first protein to be sequenced was insulin, by Frederick Sanger, who won the Nobel Prize for this achievement in 1958. The first protein structures to be solved included hemoglobin and myoglobin, by Max Perutz and Sir John Cowdery Kendrew, respectively, in 1958. Both proteins' three-dimensional structures were first determined by x-ray diffraction analysis; the structures of myoglobin and hemoglobin won the 1962 Nobel Prize in Chemistry for their discoverers.

2. Proteins
 Proteins are large complex molecules composed of long chains of amino acids called polypeptides. Proteins are polymers and amino acids are their monomers. C,H,O,S are the elements found in the proteins.

3. Amino Acids
There are 20 amino acids that are common to all life forms. The number and arrangement of these 20 amino acids yields infinite variety of proteins

4. Amino Acids are classified by their “Alkyl” “R” Group: Acidic Amino acid Basic Amino Acids Polar Amino Acids Non-Polar Amino Acids

5. Peptide Bonds Joins two amino acids into a dipeptide Bond forms between carboxyl group of one amino acid and amine group of the second amino acid Peptide bond forms by a condensation reaction losing a molecule of water with each bond

6. Primary Protein Structure

7. Helix
Most abundant 2' structure in proteins Average length = 10 aa's (~10 Angstroms) Length varies from 5-40 aa's Alignment of H-bonds creates dipole moment (positive charge at NH end) Often at surface of core, with hydrophobic residues on inner-facing side, hydrophilic on other side

8. Types of helices
"Standard" helix: 3.6 residues per turn H-bonds between C=0 of residue n and NH of residue n + 4 Helix ends are polar; almost always on surface of protein

9. Certain amino acids are "preferred" & others are rare in helices Ala, Glu, Leu, Met = good helix formers Pro, Gly Tyr, Ser = very poor Amino acid composition & distribution varies, depending on location of helix in 3-D structure

10. For more please refer our PPT. Thanks.