Kinetic analyses of DNA‐linked ribonucleases H with different sizes of DNA

A series of DNA-linked ribonucleases H with DNA adducts varying in size and sequence, ranging from heptamer to nonamer, were constructed and examined for their ability to cleave the 12-base RNA (5'-CGGAGAUGACGG-3') site-specifically. The DNA-linked RNase H with the 9-base DNA (5'-GTCATCTCC-3') cleaved the 12-base RNA specifically at A6-U7. Kinetic studies revealed that the DNA-linked RNase H with the 8-base DNA (5'-TCATCTCC-3') cleaved it slightly more effectively than that with the 9-base DNA. Factors that may affect the specificity and catalytic efficiency of a DNA-linked RNase H are described.