Amino Acids

Front 1

Cite the general structure of alpha amino acids

Back 1

NH2-CH(R)-COOH

Front 2

Define zwitterion.
What physical properties do they have?

Back 2

a species with separated opposite internal charges.
High melting point, high solubility in water, low solubility in organic solvents

Front 3

Name the R group in Glycine

Back 3

-H

Front 4

Name the R group in Alanine.

Back 4

-CH3
(neutral & hydrophobic)

Front 5

Name the R group in Phenylalanine

Back 5

-CH2-benzene
(neutral & hydrophobic)

Front 6

Name the R group in Tyrosine

Back 6

-CH2-benzene-OH

Front 7

Name the R group in Cysteine

Back 7

-CH2SH

Front 8

Name the R group in Aspartic Acid

Back 8

-CH2COOH
(ionized at physiological pH, hydrophilic)

Front 9

Write the full structure of beta-alanine.
Which carbon is alpha and which is beta?

Back 9

NH2CH2CH2COOH
The carbon attached to the carboxylate group is the alpha carbon.

Front 10

Recall the structure of GABA and its full name.

Back 10

gamma-aminobutyric acid
NH2CH2CH2CH2COOH
The carbon attached to the carboxylate group is the alpha carbon

Front 11

Discuss Huntington's chorea.

Back 11

A deficiency of GABA will result in neurological disorders including speech disturbance, irregular movements and mental deterioration

Front 12

All alpha amino acids are ____.
(regarding structure)

Back 12

With the exception of glycine, all alpha amino acids are optically active about the alpha carbon. All have an S configuration except glycine and cysteine

Front 13

Discuss PKU
(Cause, Result, Symptoms, Treatment)

Back 13

Phenylketonuria
Cause - Genetic disease
Result - absence or deficiency of phenylalanine hydroxylase which converts Phe to Tyr. Accumulation of Phe in body fluids and Phenylpyruvate in urine
Symptoms - severe mental retardation, death
Treatment - low Phe diet

Front 14

Discuss methods of diagnosing PKU

Back 14

1. Newborn urine screened for phenylpyruvate.
2. Guthrie blood test for babies
3. Prenatal diagnosis with DNA probes (genetic screening)

Front 15

Why do PKU patients have high levels of phenylpyruvate in their urine?

Back 15

Pyridoxal phosphate converts Phe to Phenylpyruvate (a metabolite) with the deficiency of Phe hydroxylase.

Front 16

Recall the metabolism of Phe to Phenypyruvate.

Back 16

1. Condensation: Phe reacts with the aldehyde of pyridoxal phosphate and yields an imine (CH=N) and water.
2. Tautomerisation: C=N shifts to the alpha carbon of Phe and the H from the alpha carbon shifts to counteract.
3. Hydrolysis: addition of water to cleave phenylpyruvate from pyridoxamine phosphate

Front 17

At which points on a pH titration curve does pH = pKa?

Back 17

At the 1st and 2nd neutralization regions where two structures (one being the zwitterion) exist in equilibrium

Front 18

What is an isoelectric point (pI)?

Back 18

This is the point at which the amino acid has an overall charge of zero.

Front 19

How can phenylpyruvate be complexed to iron?

Back 19

In a 3:1 complex with three 5-membered rings. Iron here is Fe(III)