Proteins

• Back bone of any protein chain is the combination N - C (alpha) - C
• Peptide bond is formed between amino group of one amino acid and carboxyl group of another amino acid
• Peptide bond is formed during the dehydration reaction of 2 amino acids
• To break peptide bond, hydrolysis reaction has to occur
• Glycine is the only achiral amino acid
• In all amino acids except 1 alpha-C is chiral because it has 4 distinct groups attached to it
• Proteins are synthesized in N to C direction
• Nonpolar amino acids are: glycine, alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, proline
• Acidic amino acids are aspartic acid, glutamic acid
• Basic amino acids are histidine, lysine, arginine
• Polar amino acids are serine, threonine, cysteine, asparagine, tyrosine, glutamine
• This is structure of glycine or G

  
• This is structure of alanine or A

  
• This is structure of valine or V

  
• This is structure of phenylalanine or F

  
• This is structure of leucine or L

  
• This is a structure of isoleucine or I

  
• This is a structure of tryptophan or W

  
• This is a structure of methionine or M

  
• This is a structure of proline or P

  
• This is a structure of serine or S

  
• This is a structure of threonine or T

  
• This is a structure of Cysteine or C

  
• This is a structure of asparagine or N

  
• This is a structure of tyrosine or Y

  
• This is a structure of glutamine or Q

  
• This is a structure of aspartic acid or D

  
• This is a structure of histidine or H

  
• This is a structure of glutamic acid or E

  
• This is a structure of lysine or K

  
• This is a structure of arginine or R

  
• Secondary structure of proteins are alpha-helix and beta-pleated sheet
• Secondary structure are formed from hydrogen bond between O of carboxyl group and H of amino group of another amino acid
• If there are many acidic amino acids, then active site is probably negatively charged
• If there are many basic amino acids, active site is probably positively charged
• Tertiary structure is formed by 5 forces: hydrogen bonds, ionic bonds (between acids&bases), disulphide bridges, hydrophobic interactions and van der waals
• Amino acid proline causes kinks in structure because it cannot act as a hydrogen donor d/t its structure
• Solvation layer: when hydrophobic amino acids are forced inside the protein to avoid water around it. It increases entropy of the system
• Urea disrupts hydrogen bonds in proteins
• Salts or change in pH disrupts electrostatic bonds in proteins