Amino Acids/Proteins Flashcards
what (ultimately) happens to the COOH in a Hell-Volhard-Zelinsky rxn?
One of the alpha carbon’s get’s replaced with NH2
so the structure goes from COOH to amino acid
what are the 3 reactants in the Hell-Volhard-Zelinsky amino acid synthesis?
- Br2, PB3
- H2O
- xs NH3
Why does Hell-Volhard-Zelinsky amino acid synthesis make racemic products?
Because the alpha carbon where the NH2 ends up becomes a chiral center
what is the general pka for NH3+ in an amino acid?
9-10
what happens to NH3+ if you raise its sln pH above 9-10?
the pH becomes high enough to make the NH3+ switch to basic NH2
what is the general pka for COOH in an amino acid?
2
what happens to COOH if you raise its sln pH above 2?
the pH becomes high enough to make the COOH switch to basic COO-
what does an amino acid’s pI represent?
The pH at which there is no net charge and the molecule is LEAST soluble.
Why can’t you protonate lone pairs that are participating in resonance when you adjust an amino acid in response to changes in pH?
the resonance lone pairs are not localized/not available. Lone pairs have to be localized to get protonated.
Which amino acid synthesis has COOH as its starting material?
Hell-Volhard Zelinsky
Which amino acid synthesis has aldehyde as its starting material?
Strecker
WTF is an amino acid residue?
what you get/have left when two or more amino acids combine to form a peptide and the elements of water are removed,
what remains of each original amino acid
what does the primary representation of protein structures look like?
a string of pearls with the animo acid’s 3 letter abbreviations written on them
read anal beads
what does the SECONDARY representation of protein structures look like?
a chain shown with 3D ball and stick model
usually only shows you sections of the chain and gives you a sense of the protein’s amino acid’s geometries
but says nothing of the overall protein’s shape
which representation of protein structures shows you alpha helix shapes and beta pleated shapes: primary, secondary, tertiary, or quaternary?
secondary
do beta pleated sheet shaped proteins look like curly fries or accordions?
accordions
do alpha helix shaped proteins look like curly fries or accordions?
curly fries
what does the TERTIARY representation of protein structures look like?
chewed up bubble gum;
refers to the 3D shape of the protein AS A WHOLE /shows how it folds over onto itself to increase stability of its weak bonds
what does the QUATERNARY representation of protein structures look like?
a colorful, curly hair ball?
most complicated representation; shows one big protein made out of a bunch of other proteins
what is an alpha halo acid?
…
Is the line structure for amino acids written in R configuration or S?
S; amine group will be on a wedge.
why is the tertiary/chewing gum structure of protein the most important one?
It shows you the 3d fold/shape of the entire protein.
what are the 4 types of interactions that hold tertiary structures of proteins together?
- disulfide bridges
- salt bridges
- hydrogen bonds
- hydrophobic interactions
what’s the difference between the sources of shapes for secondary and tertiary protein structures?
secondary shape is entirely based on hydrogen bonds.
tertiary shape is somewhat based on hydrogen bonds but mostly based on interactions between side chains/R groups
