In your job as a crime scene investigator, you are summoned to investigate a mys
ID: 163368 • Letter: I
Question
In your job as a crime scene investigator, you are summoned to investigate a mysterious death. A male in his early thirties, otherwise apparently healthy, is found dead in his home. There is no indication of foul play; in fact, there is no obvious cause of death at all. Upon closer inspection of the man’s home, you discover several small bits of what appear to be unusual mushrooms on the kitchen counter. Based on this observation, you play a hunch and perform a tox screen on what contents there are in the man’s bladder. Your hunch is rewarded, with the tox screen revealing the presence of alpha amanitin in the man’s urine. From this information, what do you conclude about the cause of death? In formulating your answer, be sure to talk in detail about the process that was affected in the victim. To aid you in this, use the following DNA sequence – discuss what would happen to this sequence under normal circumstances, and show the product(s) that would normally be produced by the affected process under normal circumstances. Discuss specifically what part of the process didn’t happen to cause the man’s death.
5'-TTCGACTCGGTATAAATGCCAGAAGTCCTAGAGACTGTCCTCACTCTCGTGACTAGTGCACCGCTAATGCTTGATGGGGCCCTGCCACAT..-3’
3’-AAGCTGAGCCATATTTACGGTCTTCAGGATCTCTGACAGGAGTGAGAGCACTGATCACGTGGCGATTACGAACTACCCCGGGACGGTGTA..-5’
Explanation / Answer
Alpha-Amanitin is a cyclic peptide of eight amino acids. It is possibly the most deadliest amatoxins, oxins found in several species of Amanita genus of mushrooms. The structure of the polypeptide is a typical polypeptide structure, due to the branching of the amino acid chain. A cross bridge between 6-hydroxy-tryptophan and cysteine allows the formation of a second "inner loop". The "outer loop" is formed by the normal peptide bond of the carboxyl terminus to the amino terminus of the peptide chain.
Unlike most cyclic peptides, amatoxins (and phallotoxins) are synthesized on ribosomes.
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