Peptide molecules can be classified according to the number of amino acid units joined by peptide bonds in the molecule - Scottish Highers Chemistry - Question 6 - 2016
Question 6
Peptide molecules can be classified according to the number of amino acid units joined by peptide bonds in the molecule.
Type of peptide
Example of amino acid seque... show full transcript
Worked Solution & Example Answer:Peptide molecules can be classified according to the number of amino acid units joined by peptide bonds in the molecule - Scottish Highers Chemistry - Question 6 - 2016
Step 1
Complete the table to identify the type of peptide with the following amino acid sequence
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Answer
The peptide type for the amino acid sequence alanine-glycine-valine-proline-tyrosine-serine is hexapeptide.
Step 2
Write the amino acid sequence for the original pentapeptide molecule
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Answer
The amino acid sequence for the original pentapeptide can be either isoleucine-leucine-glycine-valine-serine or serine-valine-glycine-leucine-isoleucine.
Step 3
State the term used to describe amino acids that the body cannot make
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The term used to describe amino acids that the body cannot synthesize is 'Essential'.
Step 4
Suggest why only four spots were obtained on the chromatogram of the hydrolysed pentapeptide
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Only four spots were obtained because the peptide molecule must have contained an amino acid that is repeated in the sequence, or it contained only four different amino acids.
Step 5
Draw a circle around the spot on the chromatogram that corresponds to methionine
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Answer
The Rf value for methionine in this solvent is 0.40, so draw a circle around the spot that corresponds to this distance on the chromatogram.
Step 6
Draw a structural formula for one of the amino acids that would be formed on complete hydrolysis of the above cyclic dipeptide
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A structural formula for one of the amino acids that could be formed would be:
H O
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H--N--C--C--OH
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H CH3
This represents one possible amino acid derived from the cyclic dipeptide.
Step 7
Calculate the minimum mass of death cap mushrooms that would contain the lethal dose for a 75 kg adult
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To find the minimum mass of death cap mushrooms, use the formula for the lethal dose:
Lethal dose = 100 mg/kg * 75 kg = 7500 mg
Since 1 g of mushrooms contains 250 mg of alpha-amanitin, we can set up the equation:
7500 mg = x g * 250 mg/g
Solving for x:
x = \frac{7500 mg}{250 mg/g} = 30 g
Therefore, the minimum mass of death cap mushrooms required is 30 g.
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