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BioMG 3350 Quiz 1
BioMG 3350 Amino Acid Classifications - Quiz 1
| Term | Definition |
|---|---|
| Glycine (Gly) | Nonpolar alipathic Provides least amount of steric hindrance in proteins Not particularly hydrophobic |
| Alanine (Ala) | Nonpolar alipathic Saturated hydrocarbon R group Important in hydrophobic interactions |
| Proline (Pro) | Nonpolar alipathic The only amino acid with a substituted alpha-amino group Influences protein folding by forcing a bend in the chain |
| Valine (Val) | Nonpolar alipathic Saturated hydrocarbon R group Important in hydrophobic interactions |
| Leucine (Leu) | Nonpolar alipathic Saturated hydrocarbon R group Important in hydrophobic interactions |
| Isoleucine (Ile) | Nonpolar alipathic Saturated hydrocarbon R group Important in hydrophobic interactions |
| Methionine (Met) | Nonpolar alipathic |
| Phenylalanine (Phe) | Aromatic Hydrophobic and neutral at any pH |
| Tyrosine (Tyr) | Aromatic Has -OH group that contributes polarity and H-bond capability Polar group makes it both hydrophobic and hydrophilic Can be phosphorylated |
| Tryptophan (Trp) | Aromatic Hydrophobic and neutral at any pH |
| Serine (Ser) | Polar uncharged |
| Threonine (Thr) | Polar uncharged Has -OH group that contributes polarity and H-bond capability |
| Cysteine (Cys) | Polar uncharged Can form disulfides in the right oxidizing conditions |
| Asparagine (Asn) | Polar uncharged |
| Glutamine (Gln) | Polar uncharged |
| Lysine (Lys) | Positively charged |
| Histidine (His) | Positively charged The only amino acid having an R group with a pKa near 7 Important in the active site of some proteins |
| Arginine (Arg) | Positively charged |
| Aspartate (Asp) | Negatively charged |
| Glutamate (Glu) | Negatively charged |
| Peptide bond | It is substituted amide linkage It is formed in a condensation reaction |
| Affinity chromatography | Taking advantage of unique structural or functional properties of a protein, this technique specifically removes the protein of interest from solution. |
| Electrophoresis | Proteins are separated on the basis of their ability to migrate in an electric field, an indicator of relative size. |
| Phosphorylation | The most common form of post-translational modification |
| Isometric point | Where the net charge on the amino acid is zero |
| pKa | the pH at which there is a 50:50 ratio of protonated/deprotonated species for a specific ionizable group |
| Chromatography | separate based on properties of protein charge, size, hydrophobicity |
| SDS Gel | Hydrophobic parts of the protein bind to the hydrophilic, negative parts of SDS, causing the protein to unfold. Then, a reducing agent is added to break the covalent disulfide bonds. Voltage is applied and they are ran through a gel. |
| Consensus sequences | Short stretches of highly conserved sequences |
| X-ray crystallography | Measure how the crystal diffracts x-rays main limitation: crystals can be very hard to grow |
| Nuclear magnetic resonance (NMR) | Produce the protein using heavy-isotope labeled amino acids and then measure chemical shifts of protein in solution in an NMR machine. main limitation: Currently limited to small-medium proteins <300 amino acids |
| Cryo-EM (electron microscopy) | Protein sits in different orientations in ice and is show with electron beam from above. A detector collects the shadows(electron density). Need large proteins >200kDa |
| Surface tertiary structure | Shows the solvent-accessible surface of the protein |
| Space-filling | Shows every (non-hydrogen) atom as a sphere with appropriate radius |
| Ribbon/cartoon | Traces the polypeptide backbone, highlights secondary structure |
| Hydrophobic effect | most important weak force for determining protein structure |
| two main movement constraints in peptides | planar peptide bond and steric hindrance |
| trans | 180 degrees |
| cis | 0 degrees |
| Ramachandran Plot | Shows permissible psi, phi angles |
| coil | structured but no pattern |
| loops | unstructured because of multiple configurations becomes structured when bound to other proteins |