Abstract
(I) Human RBC-PK which appeared homogeneous on disc gel electrophoresis was prepared, and its specific activity was 192 U. SDS disc gel electrophoresis of this preparation also showed single band which suggested that the RBC-PK consisted of the subunit of homogeneous molecular weight. 6 M-urea acrylamidegel electrophoresis on this preparation was carried out to examine whether RBC-PK consists of the subunit heterogeneous on electric charge. However, the examination failed of success because of the technical problem.
(II) The PK activities which seemed likely normal L-M2 hybrids on electrophoresis were isolated from rat kidney homogenate by P-cellulose chromatography. Five fractions, I, II III, IV and V in order of elution were almost identical immunologically (by anti-M1 serum) to L-4, L-3·M2-1, L-2·M2-2, L-1·M2-3 and M2-4, respectively. On the other hand, artificial L-M2hybrids was made up from L- and M2-PK according to Cardenas et al. This preparation was chromatographically separated into fractions which seemed to correspond to L-4, L-3·M2-1, L-2·M2-2, L-1·M2-3 and M2-4, respectively. Acrylamide gel electrophoretic patterns of this preparation showed binominal distribution of PK activities according to the formula (L+M2)4. Furthermore, electrophoretic migration of RBC-PK on the same experiment was almost equal to that of hybrid L-3·M2-1. It was already reported that about 25% of RBC-PK activity was neutralized by anti-M1 serum. Therefore, these results described above further extended progressively our hypothesis that RBC-PK could be hybrid form of L and M2 subunit of PK isozymes.
