| Abstract: | SYNOPSIS. Pyridoxine kinase enzyme activity was greatly increased in duckling erythrocytes infected with Plasmodium lophurae. Pyridoxine kinase activity in parasites freed from erythrocytes was much greater than that of uninfected erythrocytes. The apparent Km for pyridoxine of the parasite enzyme was 6.6 × 10-5 M whereas the host red cell enzyme Km was 1.9 × 10-6 M. Deoxypyridoxine inhibited host and parasite pyridoxine kinase activity with an apparent Ki of 1.5 × 10-6 and 8.6 × 10-6 M, respectively. These results suggest that the vitamin B6 metabolism of the malaria parasites is distinct and separate from that of the host erythrocytes. |
