Table 2.
Comparisons of live cell and in vitro assays for HGprt.
| Mutation | Live cell assay | Engineered protein assay | |||||
|---|---|---|---|---|---|---|---|
| velocity (% of normal) | velocity (% of normal) | Km of PRPP (fold of normal) | Stability after 72 h | ||||
| Hprt | Gprt | Hprt | Gprt | Hprt | Gprt | % of starting | |
|
|
|
||||||
| c.[128T>G;130 G>A] | 17.1 | 33.9 | 46.5 | 59.8 | 1.3 | 1.3 | 12 |
| c.140A>T | 2.8 | 6.2 | 75.3 | 70.4 | 3.7 | 22.5 | 32 |
| c.140A>T | 3.2 | 6.6 | 75.3 | 70.4 | 3.7 | 22.5 | 32 |
| c.143G>A | 32.7 | 54.6 | 69.9 | 107 | 2.1 | 1.6 | 49 |
| c.148G>C | 1.2 | 1.5 | NA | NA | NA | NA | NA |
| c.212G>T | 5.9 | 6.4 | 42.3 | 0.2 | 153 | 14.2 | 0 |
| c.239A>T | 20.2 | 30.9 | 53.9 | 21.7 | 3.5 | 7.2 | 16 |
| c.580G>A | 0.7 | 1.0 | NA | NA | NA | NA | NA |
| c.582C>G | 9.5 | 7.5 | 69 | 5.6 | 125.2 | 242 | 43 |
| c.582C>G | 2.4 | 1.9 | 69 | 5.6 | 125.2 | 242 | 43 |
| c.599G>C | 5.6 | 9.5 | 19.6 | 15.7 | 24 | 13.3 | 53 |
| c.601G>A | 4.8 | 9.6 | 20.6 | 7.3 | 20.6 | 28.4 | NA |
The kinetic parameters of Hprt or Gprt were normalized to the native enzyme in both live cell assay and in vitro protein assay. Data for the in vitro protein assay were derived from our prior report [8]. NA = not available.