Colored Luminosity Tryptophan synthetase, a bacterial enzyme that contains a pyr
ID: 812051 • Letter: C
Question
Colored Luminosity
Tryptophan synthetase, a bacterial enzyme that contains a pyridoxal phosphate (PLP) prosthetic group, catalyzes the synthesis of L-tryptophan from L-serine and an indole derivative.
The addition of L-serine to the enzyme produces a marked increase in teh fluorescence of the PLP group, as the adjoining graph shows. The subsequent addition of indole, the second substrate reduces this fluorescnence to a level even lower than that produced by the enzyme alone.
How do these changes in fluorescence support the notion that the enzyme interacts directly with its substrates?
Colored Luminosity Tryptophan synthetase, a bacterial enzyme that contains a pyridoxal phosphate (PLP) prosthetic group, catalyzes the synthesis of L-tryptophan from L-serine and an indole derivative. The addition of L-serine to the enzyme produces a marked increase in teh fluorescence of the PLP group, as the adjoining graph shows. The subsequent addition of indole, the second substrate reduces this fluorescnence to a level even lower than that produced by the enzyme alone. How do these changes in fluorescence support the notion that the enzyme interacts directly with its substrates?Explanation / Answer
If the serine is added to the enzyme, then it binds only with the serine group. Similalry, if the indole is added to the enzyme, then it binds to the indole group. If both are groups are added to the enzyme, then both will be binded.
So, there is no specificity for the groups which are binded. If the indole is added to the enzyme after the serine, then the peak of serine remains unchanged and the fluorescence will be increased, whereas the indole peak will be low and reduces the fluoresecence.