Amino Acid Chemistry

Question 1

Gibbs free energy

Answer 1

Negative is favorable. DeltaG=deltaH-TdeltaS.

Release of heat is favorable

Question 2

SP2 formation

Answer 2

Planar and trigonal. Peptide bonds

Question 3

Ionic bonds

Answer 3

Coulombic. Strength is 1/R^2.

Question 4

Hydrogen bonds

Answer 4

Length 1.5 to 2.5 A. Proton shared between electronegative ions. Strongest involve O

Question 5

Van der Waals

Answer 5

Electrostatic. 1/R^6.

Question 6

Hydrophobic effect

Answer 6

Not attractive, driven by entropy.

Question 7

Carbonyl with aldehyde.

Answer 7

Glucose involved. Beta beside and alpha away.

Question 8

Glucose conformation

Answer 8

99% ring. 2/3 if that beta form.

Question 9

Maillard reaction

Answer 9

Glucose + amino acid

Cataracts

Question 10

Acids pka

Answer 10

Less than seven

Question 11

Base pka

Answer 11

More than seven

Question 12

pH definition

Answer 12

pKa when acid=conjugate base

Question 13

Henderson Hasselbach equation

Answer 13

pH=pKa + log(A-/HA)

Question 14

Buffers

Answer 14

Made of acid and conjugate base. pKa=-log(Ka).

Plus or minus one best buffer

Question 15

Major biochem buffer

Answer 15

Bicarbonate. Not great, because dynamic pH needed for reactions.

Question 16

Amino acids

Answer 16

Are L isomers in bio. Have amine group, carboxyl group, and R group.

Question 17

Dicarboxylic acids

Answer 17

Oxalic, Malonic, succinic, glutaric

Question 18

pKa values in amino acids

Answer 18

Carboxyl-3
Aspartic and glutamic-4
Histidine-6
Amino group, and cysteine-8
Tyrosine and lysine-11
Arginine-12

Question 19

Groups charged at physio pH

Answer 19

Carboxyl, aspartic, glutamic, negative. Amino, lysine arginine positive.

Question 20

Zwitterions

Answer 20

Positively and negative charged. Have N +1 protonation states. N is number of ionizeable groups.