Clements J E, Rogers S G, Weiss B
J Biol Chem. 1978 May 10;253(9):2990-9.
An endonuclease purified from Hemophilus influenzae made single strand breaks in DNA containing apurinic or apyrimidinic sites but had no detectable endonuclease activity on untreated native DNA. The new 5'-termini created at the cleavage sites were base-free deoxyribose 5-phosphate residues. The enzyme preparation also catalyzed the exonucleolytic release of 5'-mononucleotides from bihelical DNA and the hydrolysis of DNA 3'-terminal phosphomonoesters. The phosphatase-exonuclease activity was indistinguishable from that reported by Gunther and Goodgal (J. Biol. Chem. (1970) 245, 5341-5349) and resembled that of exonuclease III of Escherichia coli. The endonucleolytic and exonucleolytic activities could not be separated by electrophoresis, sedimentation, or gel filtration, and they were also affected simultaneously by mutation. The enzymatic activities appear to be functions of a single monomeric protein (M(r) = 30,000).
从流感嗜血杆菌中纯化得到的一种核酸内切酶，可在含有脱嘌呤或脱嘧啶位点的DNA上产生单链断裂，但对未处理的天然DNA没有可检测到的核酸内切酶活性。在切割位点产生的新的5'-末端是无碱基的脱氧核糖5-磷酸残基。该酶制剂还催化从双螺旋DNA中外切核酸酶释放5'-单核苷酸以及DNA 3'-末端磷酸单酯的水解。磷酸酶-外切核酸酶活性与Gunther和Goodgal报道的活性无法区分（《生物化学杂志》（1970年）245卷，5341-5349页），并且类似于大肠杆菌的外切核酸酶III的活性。核酸内切酶和外切核酸酶活性不能通过电泳、沉降或凝胶过滤分离，并且它们也同时受到突变的影响。这些酶活性似乎是单一单体蛋白（分子量=30,000）的功能。
