TABLE II.
Ndpk, histidine kinase and exonuclease activities of Nm23-H1 variants
| Protein | NDPK1 | Histidine kinase2 | Exonuclease3 |
|---|---|---|---|
| WT | 627 ± 36d (100) | 9.9 (100) | 28.4 ± 4.0 (100) |
| E5A | 438 ± 31c (70) | 8.2 (83) | 3.4 ± 1.5* (12) |
| K12Q | 14 ± 0.9a (2) | 0.9 (9) | 5.2 ± 3.5* (18) |
| Q17N | 516 ± 10c (82) | 6.5 (66) | 31.4 ± 6.0 (110) |
| Y52A | B.D.a | 0.4 (4) | 25.3 ± 3.9 (89) |
| P96S | 127 ± 5b (20) | 1.1 (11) | 24.9 ± 5.1 (88) |
| H118F | B.D.4 | B.D. | 33.0 ± 9.0 (116) |
NDPK activity is expressed in units/mg (mean ± S.E.), derived from at least three replicate measurements and three independent protein preparations. Activity expressed relative to wild-type is displayed in parentheses.
Histidine kinase activity is expressed as the percent of 32P radiolabeled NM23-H2 substrate converted to a phosphorylated per minute.
Exonuclease activity is expressed in fmol of 32P liberated from radiolabeled nucleotide substrate per 5 min (mean ± SE) as determined with three replicate measurements for at least three independent protein preparations.
B.D., below detection.
Means not bearing a common superscript are significantly different (p ≤ 0.01), as determined by one-way ANOVA and mean separation by Student’s t-Test.
Means bearing an asterisk within a column are significantly different (p ≤ 0.05), as determined by one-way ANOVA and mean separation by Student’s t-Test.