DNA cleavage function of seryl-histidine dipeptide and its application.

The double-stranded DNA or circular plasmid DNA can be cleaved by the Ser-His dipeptide by hydrolysis of the DNA-phospho-diester bond. The proper sequential order of the amino acids serine and histidine is apparently crucial in its unique cleavage activity as compared to the other di- or tri-peptides containing one of these amino acids. An inverted sequence of this dipeptide to a His-Ser linkage renders the peptide ineffective in the cleavage of DNA. In addition to the DNA cleavage function, Ser-His is also capable of cleaving other molecules, e.g., proteins, esters and RNAs. The cooperative actions of the hydroxyl group and the basic groups in the serine and histidine or related amino acids can be found in contemporary enzymes, such as DNase, serine proteases, lipases, esterases, chymotrypsin, trypsin, and elastase, etc. The Ser-His and related oligopeptides might have played important roles in the evolution of enzyme functions.