Abstract: The present invention is directed to an isolated and purified DNA encoding a biologically active fragment of a thermostable, full length DNA polymerase I enzyme of Bacillus stearothermophilus. More particularly, the invention is directed to a DNA encoding an approximately 66,000 dalton DNA polymerase that lacks 273 amino acids from the N-terminus of the approximately 96,000 dalton B. stearothermophilus DNA polymerase I, and to the protein encoded thereby which has been designated the B. stearothermophilus DNA polymerase I exo- fragment. The enzyme fragments are useful in DNA sequencing, cDNA preparations, thermophilic Strand Displacement Amplification and other molecular biology applications.

Abstract: The present invention is directed to materials and methods for the quasi-random and complete fragmentation of DNA using restriction endonuclease reagents capable of cutting DNA at a dinucleotide sequence. The invention is also directed to methods for labeling DNA using template-specific oligonucleotides, for shotgun cloning, for sequencing of DNA, for epitope mapping and for anonymous primer cloning, all using fragments of DNA generated by the method of the present invention.

Abstract: DNA sequences encoding a novel restriction endonuclease (designated R.C.nu.iJI) and variants thereof are disclosed along with method and materials for production of the same by recombinant methods. A bacterial host cell line transformed with DNA encoding R.C.nu.iJI is also disclosed, as well as methods for expressing R.C.nu.iJI in the bacterial host system and subsequent materials and methods for purification of the enzyme.