Chapter 4- Amino acids

What is the generic structure of an amino acid?

-Alpha carbon - Amino group -Carboxyl group -Hydrogen -R group

Disulfide bond is most abundant as an________

-amid

What is the net charge at isoelectric point?

0=no charge

Ibuprofen has how many chiral carbons? Which configuration is active? S or R?

1. S is active

What mixture of enantiomers exist in nature?

50/50

How many amino acids have uncharged polar side chains?

6. - Serine -Threonine -Asparagine -Glutamine -Tyrosine -Cysteine

How many amino acids have nonpolar side chains?

9. - Glycine -Alanine -Valine -Leucine -Isoleucine -Methionine -Proline -Phenylalanine -Tryptophan

If an amino acid has the same composition but different sequences they are said to be_____________from one another

Different

When determining L and S configurations you determine which substituent is most________________.

ionizable

When an amino acid is isoelectric at a certain pH, this pH is where it is__________.

neutral

The amino pH is 9.5, the carboxyl pH is 2.5. What is the isoelectric point?

pH=6 because that is the midpoint between the two

The amino acid derivative and modified amino acid is basically the_________

same

All amino acids are chiral except for?

Glycine

Which drug when you give both enantiomers causes toxicity and birth defects? How did they not know they were giving both?

Thalidomide The enantiomers are connected in this case

At physiological pH the N-terminus is protenated and the C terminus is deprotenated. True or False

True

The formation of a disulfide bond can be both intramolecular and intermolecular. True or False

True

Peptide bonds are no more than a regular__________

amide bond

Chirality has an effect on the shape of___________ and ___________

amino acids and proteins

What are consequences of amide (peptide) bond formation?

- Directionality (amino and carboxyl end) -No free rotation around the bond

Ionizable R groups are important in determining pI. Which amino acids have R groups that can be ionized?

- Lysine -Argenine -Histadine -Aspartic acid -Glutamic acid

What is the difference between composition and sequence?

Composition= number of each amino acids in a peptide or protein Sequence- order in which the amino acids are in

Amino acids are linked by peptide bonds at the protenated N terminus of one amino acid and the deprotenated C terminus of another amino acid through which reaction?

Condensation-loss of water.

Which amino acid is the only one that can form disulfide bonds?

Cysteine

Amino acids cannot act as both an acid and a base. True or false

False

What does it mean for a carbon to be chiral?

Have 4 different substituents

All our amino acids are in what configuration? L or S?

L

Are amino acids most or least soluable at isoelectric point?

Least soluable

Primary structure is the sequence of amino acids from what end to what end?

N-terminus to C-terminus

Forming a disulfide bond is what kind of reaction?

Oxidation (redox) reaction between 2 cysteines

What bonds link amino acids together? These bonds are also known as?

Peptide, covalent

______________is the foundation for all other elements for protein structure

Sequence

Amino acids are the building blocks for___________.

Proteins

After amino acids are incorporated into a peptide they are now referred to as amino acid__________

Residues

Amino acid derivatives and modified amino acids are?

Taking an amino acid and adding something to it

Does forming a peptide bond require energy?

Yes

What is the isoelectric point (pI)?

where the positive and negative charge are equal to 0