Patent ID: 6849404

Claim:
A process for preparing a library of DNA fragments of which terminal sequences are known by using a DNA of which base sequence is completely unidentified, which comprises: i) digesting a DNA into fragments which have single-strand cohesive ends by using a restriction enzyme, ii) preparing a series of hairpin loop adapters which have single-strand cohesive ends of which base sequence is known; iii) ligating the DNA fragments with the hairpin loop adapters prepared in the above step ii) by using a DNA ligase; iv) removing DNA fragments and hairpin loop adapters which have not participated in the ligation reaction by using an exonuclease; and (v) eliminating a hair pin loop structure only from the DNA fragments which contain the hairpin loop adapters, obtained in step iii), by using an alkaline solution, am RNase or a single strand specific exonuclease.