title: A novel endonuclease from kinetoplastid hemoflagellated protozoan parasite Leishmania.
abstract: A nuclease activity has been purified from the nuclei-kinetoplast fraction of Leishmania. This enzyme, termed endonuclease M (Endo M), is shown by electrophoresis in a denaturing polyacrylamide gel to be associated with a single polypeptide of molecular mass 52 kDa. Physical analysis of the enzyme indicates that it has a sedimentation coefficient S20,w of 4.5S, a Stoke's radius of 32.5 A, and a native molecular mass of 53 kDa. The final Mono Q purified Endo M possesses both DNase and RNase activities. It acts as an endonuclease by introducing random single-stranded nicks into the supercoiled DNA molecules, that often leads to its linearization due to nicking at the opposite strands, and subsequent degradation of the DNA with further incubation. Single-stranded DNA is twice preferred to double-stranded DNA as substrate. Single-stranded RNA is also degraded rapidly and is competitive as a substrate with single-stranded DNA. RNA:DNA hybrids, however, are largely resistant to the Endo M digestion.
authors.affiliation: Molecular Parasitology Laboratory, Indian Institute of Chemical Biology, Calcutta, 7000032, India.
authors.forename: B
authors.initials: B
authors.lastname: Mittra
authors.forename: P K
authors.initials: PK
authors.lastname: Sadhukhan
authors.forename: H K
authors.initials: HK
authors.lastname: Majumder
mesh_terms: D000818:Animals; D003851:Deoxyribonucleases / Q000378:metabolism; D004720:Endonucleases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D007891:Leishmania / Q000201:enzymology*; D008970:Molecular Weight; D015800:Protozoan Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism
chemical_list: D015800:Protozoan Proteins; D003851:Deoxyribonucleases; D004720:Endonucleases; D012260:Ribonucleases; C117554:endonuclease M