[The physicochemical properties of the DNAse of Mycoplasma fermentans PG-18]. / Fiziko-khimicheskie svoistva DNK-azy Mycoplasma fermentans PG-18.

Physical and chemical properties, as well as polypeptide structure of DNAse from Mycoplasma fermentans PG-18, have been determined. The enzyme in a native form exists probably as a decamere (10X34 kD) and manifests maximal activity at weak alkaline pH range. The temperature optimum of the enzyme is --37 degrees C. DNAse appears to be Mg2+-dependent and has its maximal activity at 10 mM MgCl2. EDTA completely inhibits DNAse activity. The given DNAse has been determined to cleave a phosphodiether bond in 3'-position of deoxyribose and to have both exo- and endonuclease activity, since it has hydrolized both native linear doublestranded DNA and closed-circle plasmid DNA.

[The isolation and purification of a nonspecific DNAse from Mycoplasma fermentans PG-18]. / Vydelenie i ochistka nespetsificheskoi DNK-azy Mycoplasma fermentans PG-18.

Nonspecific endogenic DNAase has been isolated from biomass of Mycoplasma fermentans PG-18 cells and purified to the homogeneous state. The scheme of isolation consists of purification stages on columns with phosphocellulose, DNA-cepharose CL-8B and phenylcepharose. DNAase was not bound to phosphocellulose, its volume was equal to zero. Then this DNAase was passed through column with DEA-cepharose CL-6B (elution by gradient KCl from 0.1 to 1.8M): enzyme was eluted at KCl concentration in the eluting buffer from 0.1 to 1.2 M. The enzyme was purified to the homogeneous state on column with phenylcepharose (elution by linear gradient of ethylene glycol from 30 to 80%): enzyme was eluted at the concentration of ethylene glycol in the eluting buffer from 43 to 80%. According to data obtained using gel-electrophoresis, under the denaturing conditions molecular mass of enzyme in acrylamide gel was 34 kDa.