Serratia marcescens nuclease' (, endonuclease (Serratia marcescens), barley nuclease, plant nuclease I, nucleate endonuclease) is an enzyme. This enzyme catalyses the following chemical reaction

: Endonucleolytic cleavage to 5´-phosphomononucleotide and 5´-phosphooligonucleotide end-products

Hydrolyses double- or single-stranded