The enzyme hypoxanthine guanine phosphoribosyl transferase (HGPRT) isolated from a child with Lesch-Nyhan syndrome is compared with HGPRT isolated from a healthy control individual. The results are shown in the graph below (Lineweaver-Burk plot showing Lesch-Nyhan patient HGPRT has higher Km than control). Which of the following is the best conclusion about the HGPRT from the child with Lesch-Nyhan disease?

1. A)There is more HGPRT in the Lesch-Nyhan cells.
2. B)There is an activating mutation in the HGPRT from the Lesch-Nyhan patient.
3. C)The enzyme has a lower affinity for guanine than the control enzyme.GABARITO
4. D)The gene for HGPRT is repressed in the Lesch-Nyhan patient.
5. E)A competitive inhibitor was added to the enzyme from the Lesch-Nyhan patient.