T-lymphoblast-specific nucleoside kinase: characterization and comparison with deoxycytidine kinase

The results of Sephadex G-100 gel filtration and sucrose density gradient centrifugation showed that T-lymphoblast-specific nucleoside kinase (TSK) purified from MOLT 4FT cell extract has a molecular weight of 26,500, while deoxycytidine kinase (dCK) 56,000. The pI value of TSK (pH 8.2) is quite different from that of dCK (4.8). TSK phosphorylated deoxycytidine, deoxyadenosine, deoxyguanosine and arabinocytidine, similar to dCK, but the respective kinetic properties were quite different. In the phosphate donor specificity and metal ion requirement, some differences were observed between TSK and dCK. dTTP was a good phosphate donor for dCK but no effect at all as phosphate donor for TSK. dCK was inhibited at very low concentration of dCTP, but TSK at much higher concentration of dCTP.