biochem1: week 1
DESCRIPTION
Semester 1 - Biochemistry - Week 1TRANSCRIPT
Semester 1: Biochemistry
Proteins, Carbohydrates,
Week 1
Proteins L-amino acids: Zwitterions =
physiologic pH Buffer =
pKa±1 pI =
pKa average
Hydrophobic Amino Acids
Aliphatic: VAGLIP Valine (Val) Alanine (Ala) Glycine (Gly) Leucine (Leu) Isoleucine (Ile) Proline (Pro)
Hydrophobic Amino Acids
Aromatic: Form Your Wheel Phenylalanine (Phe/F) Tyrosine (Tyr/Y) Tryptophan (Trp/W)
Sulfur: Musky Crap Methionine (Met) (Cysteine (Cys)) ←(Hydrophilic)
Hydrophilic Amino Acids
Polar/Uncharged:3 Serene Gluttonous Asians
Threonine (Thr) Serine (Ser) Glutamine (Gln) Asparagine (Asn)
Hydrophilic Amino Acids
Acidic/Negative: Gluteus = Ass Glutamate (Glu) ←(Glutamine = Gln) Aspartate (Asp) ←(Asparagine = Asn)
Basic/Positive: Hiss! Lyse! Argh! Histidine (His) Lysine (Lys) ←(pKa = 7) Arginine (Arg)
Protein Structure Primary: amino acid sequence
Peptide bond = amide linkage between carboxyl group and next amine (mostly trans configuration)
Quick note: Configuration = must break bond to
change (cis vs. trans, D vs L, R vs S) Conformation = molecular motion to
change form (chair vs. boat)
Protein Structure Secondary:
Alpha-helix: (E.G., alpha-Keratin) Few bulky (Ile, Val) or tiny (Pro, Gly) R's 3.6 residues/turn
Beta-sheet: (E.G., Fibroin of silk) Backbone H-bonds = perpendicular
between sheets Not regular, repeating pattern.
Random-coil: Not random configuration Usually functional portion of protein
Protein Structure Tertiary structure: 3D folding
Domains of functionality
Types: Globular: H2O soluble (E.G., Pepsin) Fibrous: (E.G., Collagen)
Bonds: Hydrophobic (interior) Salt bridges (exterior) Disulfide links Van der waals Side-chain H-bonds
Collagen Tough and fibrous; in skin, hair, and nails Triple α-helix (R=Proline/Hydroxyproline)
Needs Vitamin C (or suffer from Scurvy) Cysteine (strong, covalent disulfide) bonds
Less cysteine = curlier hair!! ←(unimportant)
4 protofibrils→microfibril→macrofibril→hair
Protein Structure
Protein Structure Quaternary Structure:
>2 tertiary structures combine as subunits
Disulfide bonds are RARE
Prions Normal cell surface proteins gone bad Normal protein gene: PRNP (chromosome 20) Normal protein: Prpc Prion (mutated protein): Prpsc (scrapie) Infective post-mortem Diseases:
Creutzfeldt-Jakob disease (Mad Cow; Xmotor)
KURU (from cannibalism)
Spongiform Encephalopathies Alzheimer's (Xmemory) New variant Creutzfeldt-Jakob's (Xmotor) Fatal Familial Insomnia (Amyloid) Parkinson's (tremor, Xmotor)
Stereochemistry Achiral: superimposable mirror images with four
groups
Chiral: bound to four or more unique groups; implies stereoisomers (same formula but different bond placements; Z/cis vs E/trans)
Enantiomers: non-superimposable mirror images with same properties but rotates light differently (D vs. L)
Diastereomers: non-mirror image stereoisomers (D-glucose vs. D-galactose)
Carbohydrates D-glucose: 4 chiral centers
Diastereomer w/D- galactose:
Mutarotation: equilibrium between alpha and beta forms
Anomeric: linear = non-chiral, ring's C1 = chiral (E.G., fructose)
Anomers
Bonds to Know Maltose/Amylose: alpha(1-4) Lactose/Cellulose: beta(1-4) Sucrose: alphaDGlu-betaDFru Amylopectin: alpha(1-4); branches:
alpha(1-6) Also know that all monosaccharides are
reducing sugars because of OH on C1 (hemiacetal)
Love,Julie and Jenesha