Table 1. Specific activities of human wild-type and mutant DGUOK enzymes with the phosphate acceptors.
Samples containing 5 μg of mitochondrial protein were assayed under standard conditions (see the Subjects and methods section). The phosphate acceptor concentrations were 50 μM for both dG and dA. The ATP/MgCl2 concentration was fixed at 5 mM/6 mM. For patients and carriers, assays were performed on two different mitochondria-enriched preparations and mean values are shown with the range in parentheses. V is given in picomoles of dG or dA phosphorylated per hour per milligram of protein. Also shown is the percentage of the mean control value.
| V50 μM | ||
|---|---|---|
| dG | dA | |
| Controls (up to 1 year of age) | ||
| Mean | 769 | 2145 |
| Range (n) | 670–905 (6) | 1580–2825 (6) |
| Patients | ||
| Patient 1 (N46S, L266R) | 107 (105–110) (14%) | 214 (197–231) (10%) |
| Patient 2 (c.142+1G>A, c.591G>A) | 21 (16–27) (2.7%) | 26 (25–27) (1.2%) |
| Patient 3 (c.763_766dupGATT) | 20 (4–36) (2.6%) | 22 (17–27) (1%) |
| Controls (36–42 years of age) | ||
| Mean | 808 | 2035 |
| Range (n) | 655–975 (6) | 1546–2682 (6) |
| Carriers | ||
| Mother (N46S) | 495 (475–515) (61%) | 1201 (1128–1274) (59%) |
| Father (L266R) | 337 (314–361) (42%) | 834 (807–861) (41%) |
| Brother (N46S) | 361 (344–378) (45%) | 895 (864–926) (44%) |
| Mother (c.763_766dupGATT) | 355 (336–374) (44%) | 855 (817–893) (42%) |