Deoxyribonuclease I (EC 3.1.21.1) and II (EC 3.1.22.1)

From Chapter 1 on nucleases, we know that the term DNase refers to an enzyme that endonucleolytically cleaves DNA molecules. This chapter deals with those DNases that preferentially catalyze the hydrolysis of double-stranded DNA (ds DNA) and that have found a use in the various techniques employed in molecular biology, The Type II restriction endonucleases obviously fall into this category, however they are a large subject on their own and therefore are dealt with in a separate section of this book. DNases acting preferentially on single-stranded DNA (ss DNA) substrates are also dealt with in another section of this chapter.