Biochem1: Week 1

Semester 1: Biochemistry

Proteins, Carbohydrates,

Week 1

Contact us:

Julie: julieyumi@gmail.com

Jenesha: jnarayanan@rossmed.edu.dm

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