Characterization of the deoxyribonuclease determined by lambda reverse as exonuclease VIII of Escherichia coli. |
| |
Authors: | J R Gillen A E Karu H Nagaishi A J Clark |
| |
Affiliation: | Department of Molecular Biology and Department of Biochemistry University of California, Berkeley, Cal. 94720, U.S.A. |
| |
Abstract: | Gottesman et al. (1974) detected a new DNAase in Escherichia coli infected with λ reverse, a recombination-proficient substitution mutant of phage λ which is deleted for the λ recombination genes. We have purified this enzyme, using the procedure developed for the purification of exonuclease VIII (Kushner et al., 1974), a DNAase produced by E. coli K-12 strains carrying sbcA? mutations. The λ reverse exonuclease (Exoλrev) is identical to exonuclease VIII by several criteria. The two enzymes elute at similar salt concentrations from DEAE-cellulose and DNA-cellulose; sediment at the same velocity in glycerol gradients, corresponding to a molecular weight of about 1.4 × 105; migrate at the same RF in sodium dodecyl sulfate/polyacrylamide gels, indicating a polypeptide molecular weight of 1.4 × 105; exhibit maximum activity at 20 mm-Mg2+ and pH 8 to 9; and are much more active on double-stranded DNA than on heat-denatured DNA. Both enzymes are rendered sedimentable by antiserum against Exoλrev. This evidence supports the hypothesis that the non-λ DNA substitution in λ reverse includes recE, the structural gene for exonuclease VIII. |
| |
Keywords: | SDS sodium dodecyl sulfate |
本文献已被 ScienceDirect 等数据库收录! |
|