Proteins
- Created by: Breedelahaye2020
- Created on: 19-10-20 22:12
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- Proteins are very important class of foof moleccules because they provide an organism not only with carbon and hydrogen, but with nitrogen and sulfur.
Stereoisomers for Amino Acids
- The carbon is attached to four diffrent groups in all amino acids except glycine
- Carbon of most amin acid is therefor chiral, allowing mirror image forms, enatiomers to exit
- Glycine has two hydrogen atoms attached to the carbon and is the only amino acid commonly found in proteins that is not chiral
- The L-configuration of amino acids is isolated from proteins
- The d notation is very similar to that discussed for carbonhydrates, but instead of the OH group we use the NH group to determine the D and which is L
- Structures of amino acids at pH 70
- General structure of an amino acid
- Structures of the amino acid having hydrophobic, polar, neutral negativvely charged and positively charged R groups
- The primary structure of a protein is the amino acid sequence of the protein chain
- Results from the covalent bonding between the amino acid residues in the chain.
Secondary structure
- Repeating structures define the secondary structure of the protein
- Secondary structure is the result of hydrogen bondong between the amide hydrogens and carbonyl oxygens of the peptide bonds
- Most common type of secondary structure is a coiled, helical conformation lnown as the helix.
- The helix has several important features
B pleated sheet
- Secondary common secondary structure in protein resembles the pleated fold of drapery and is known as B pleated sheets
- All of the carbonyl oxygens and amide hydrogens in a B pleated hseet are involved in hydrogen bonds, and the polypeptide chain is exxtended.
- Polypeptide chains in a b pleated sheet can have two orientations
- N termini are heat to head, structure is known as a parallel B pleated sheet
- N terminus of one chain is aligned with the C terminus of a second chain, structure is known as an antiparallel B pleated sheet.
- The association of several polypeptides to produce a functional protein defines the quaternary structure of protein.
Myoglobin and Hemoglobin
- To overcome solubility problem, we have…
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