Question: In a certain prokaryotic organism the gene for the glycolytic
enzyme glucose-6-phosphate isomeras…
In a certain prokaryotic organism the gene for the glycolytic
enzyme glucose-6-phosphate isomerase encodes for a protein with
molecular weight of about 59,950 daltons. This enzyme uses a
glutamate residue as a general acid/base catalyst in the mechanism
of this enzyme. The average molecular weight of an amino acid is
110 daltons.
a.How many moles of glucose are required to produce one mole of
this enzyme starting with transcription and ending with the
complete translation of this protein?
b. If the codon encoding for the active site glutamate has a
point mutation such that the purine is replaced with a pyrimidine
in the third position of the codon, what will be the most likely
result for the activity of this enzyme? Why?
c. Do you think this mutation will have a greater impact on the
Km, Vmax or both for this enzyme? Why?
d. This organism has a Shine-Dalgarno sequence comparable to the
consensus sequence found in many bacteria – AGGAGGU. There is a
strain of this organism that is viable and can grow on glucose, but
it has a mutation in the Shine-Dalgarno sequence – AGGAGAA. This
strain can produce norm amounts of mRNA, but decreased amounts of
the fully functional enzyme. Explain these observations.
