FOB 2 amino acids

• pH and effects on acids and bases

  a measure of the concentration of hydrogen ions present in an aqueous solution. basic - more hydroxide, acidic - more hydrogen. if something is acidic it will become more acidic in a basic solution and vice versa
• amino acid structure

  monomeric units that form peptides and proteins. carboxylic acid (weak acid) and amine group (weak base) hydrogen and r group (determines protein properties). at biological pH of 7.4 carboxylic acid is H3N+ protonated and carboxylic acid will be COO- deprotonated.
• naming amino acid

  carboxylic acid is carbon one, then alpha, beta, gamma, delta etc. named based on which carbon the amino group is on. carboxylic acid and amine group on alpha carbon - alpha-amino acid (proteinogenic amino acid, monomers for proteins).
• amino acids in the body

  amino acids make DNA then rna then protein. there are 20 standards of which 9 essential (must be from diet), and 11 are non-essential (synthesised). neurotransmitters like Glutamic acid (excitatory) GABA (inhibitory)
• chirality of amines

  L form is predominant form. coo- then h then r then Hh3 + (left to right clockwise) because enzymes have a preference towards the L form
• amino acid families

  classified by R groups: non-polar, aromatic, polar, negatively charged (acidic), positively charged (basic)
• amino acids conventions and properties table

  amino acid group (polar, nonpolar, aromatic, positively charged, negatively charged), name, abbreviation/symbol, molecular weight, pK of CooH (2), nh3+ (9) and r group (ph below pka protonated etc), pi (isoelectic point, net neutral charge), hydropathy index (- hydrophilic, + hydrophobic) and occurrence in proteins % (how common they are)
• non-polar r group example

  alanine cH3

  
• polar r group

  serine ch2oH

  
• aromatic r group

  phenylalanine Ch2 benzene ring

  
• negatively charged r group

  aspartate Ch2 coo-

  
• postivley charged r group

  lysine Ch2 x 4 + Hh3+

  
• protonated vs deprotonated functional groups


  protonated NH3+ / d NH2 - protonated COOh / d COO-
• pKa


  the log of the acid dissaciation constant. the lower the stronger the acid, the higher the stronger the base. carboxyl pka 2, main pka 9
• pI

  isoelectric point. the pH at which an amino acid carries no net charge (referred to as a zwitterion). all carboxyl groups are deprotonated and all amino groups are protenanted, so charges cancel each other out. below pI positive, above pI negative pI = 1/2(pka1 + pka2) (average of both pkas)
• residue

  amino acids bonded together once water is lost. residue average is 110g/mol
• titration for amino acid

  has two equivalence points in acidic and basic conditions due to acid and base functional groups