organic materials Flashcards
amino acid ‘R-group’ properties
(side chain)
polar (OH) / non-polar (CH₃)
proton donor (COOH) / proton acceptor (NH₂)
acid-base properties of amino acids
di-functional from NH₂ & COOH
∴ amphoteric depending on pH of the solution environment
NH₂ → NH₃⁺ & COOH → COO⁻
zwitterion in solution
(dipolar ion)
overall neutral amino acid containing both positive & negative change
present at isoelectric point (pH)
amino acid in low pH (pH < pI)
zwitterion + abundance of H₃O⁺ → cation + H₂O
amino acid in high pH (pH > pI)
zwitterion + abundance of OH¯ → anion + H₂O
condensation polymerization reaction of 2-amino acids (α-amino acids)
NH₂ & COOH react together to form a peptide (amide) link (CONH) + H₂O
N-terminal amino acid
end of the polypeptide chain with a free amino group
C-terminal amino acid
end of the polypeptide chain with a free carboxyl group
primary structure of protein
sequence of amino acids joined by covalent peptide bonds
secondary structure of protein
hydrogen bonding between N-H & C=O causes folding into α-helices (polypeptide coils into a spiral) or β-pleated sheets (polypeptide folds into parallel layers)
tertiary structure of protein
3D shape formed through forces between R-groups of amino acids
e.g. covalent disulfide bridge (S-S) & ionic salt bridge (NH₃⁺/COO⁻)
(hydrogen bonding, dipole-dipole attraction, dispersion forces)
interial hydrophobic & exterial hydrophilic R-groups
quarternary structure of protein
multiple polypeptide chains (& sometimes non-protein molecules) form large complex functional units held together by dispersion forces
(e.g. haemoglobin)
hydrogen bonding, dipole-dipole attraction & ionic interactions may also be present
characteristics of biological enzymes
proteins that catalyze biochemical reactions by providing an alternate reaction pathway with lower activation energy
sensitive as changes in temperature or pH may disrupt the forces that determine their tertiary structure
active sites are substrate specific
describe the effect of changing temperature/pH on an enzyme ?
enzymes are are temperature/pH specific
changes can disrupt the forces that determine their tertiary structure
active sites no longer binds to the substrate
triglycerides
condensation reaction between glycerol (propane-1,2,3-triol) & 3 fatty acids
OH (glycerol) + COOH (fatty acid) → ester link (COO) + H₂O
saturated fatty acids
hydrocarbon chains with only C-C bonds