Abstract
Deoxyribonuclease (DNase) activities have been partially purified from human serum and pancreas. Several of their physical and enzymatic characteristics were determined and compared in order to evaluate their relatedness. Human serum deoxyribonuclease has an isoelectric point in the range of 3.9 to 4.3 and a molecular weight of 33,000 to 38,000. Optimal enzymatic activity at pH 7.0 was dependent on both Mg2+ and Ca2+, whereas a pH optimum of from 5.5 to 5.8 was observed in the presence of Mg2+ and ethylene glycol bis(beta-aminoethyl ether)N,N,N',N'-tetraacetic acid (EGTA). The proportion of single strand or double strand breakage products at early stages of DNA digestion were variable functions of the composition of the buffers employed for the reactions. Single strand break age was predominant under all reaction conditions. Double strand breakage occurred with greatest frequency under neutral conditions in the presence of Mg2+ and Ca2+, was inhibited by the inclusion of 0.15 M NaCl, and did not occur at pH 5.8 in the presence of Mg2+, EGTA, and 0.15 M NaCl. Human pancreas deoxyribonuclease exhibited essentially the same physical properties and enzymatic characteristics as those of the human serum enzyme. Thus, human serum deoxyribonuclease may originate in this pancreas.
Highlights
Deoxyribonuclease (DNase) activities have been partially purified from human serum and pancreas
Human serum deoxyribonuclease has an isoelectric point in the range of 3.9 to 4.3 and a molecular weight of 33,000 to 38,000
DNase Assay-In order to aid the enzyme purification and make quantitative measurements of DNase activity in different samples, we developed a new fluorometric
Summary
Deoxyribonuclease (DNase) activities have been partially purified from human serum and pancreas. Several of their physical and enzymatic characteristics were determined and compared in order to evaluate their relatedness. Double strand breakage occurred tith greatest frequency under neutral conditions in the presence of M&+ and Ca’+, was inhibited by the inclusion of 0.15 M NaCl, and did not occur at pH 5.8 in the presence of Mg’+, EGTA, and 0.15. Strong and Hewitt [1] have observed at least five neutral, cofactor-dependent isozymes of deoxyribonuclease (DNase) activity in human serum and plasma which are distinguishable by their electrophoretic mobilities in DNA-polyacrylamide gels [2]. Preliminary characterization of the cofactor dependence and the pH optimum of the activities indicated similarities with those previously reported for the activity in unfractionated serum [3] or partially purified from human serum [4, 5]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have