Studies on 3′-Nucleotidase-nuclease from Potato Tubers: I. Purification and Some Properties of the Enzyme

Sugar non-specific endonucleases

“…However, nucleases from A. espejiana [81], N. crassa (mitochondria) [11] and tea leaves [42] show di¡erent pH optima for the hydrolysis of ssDNA (8.8, 6.5^7.5 and 6.0) and doublestranded DNA (dsDNA) (8.0, 5.5^6.5 and 5.5, respectively). On the other hand, 3P-nucleotidase-nuclease from potato tubers showed di¡erent pH optima for the nucleotidase (pH 8.0) and nuclease (pH 6.5^7.5) activities [41]. Similarly, nuclease I from rye germ ribosomes exhibited pH optima of 6.0 and 6.5 for the nuclease and 3P-nucleotidase activities, respectively.…”

“…During the initial puri¢cation steps, one of the primary aims is to get rid of the colored impurities contributed by pigments of the organelles and this is achieved either by extraction with acetone^water mixture (4:1 v/v) [42] or by a simple wash with ammonium chloride followed by high speed centrifugation [47,48]. In most cases apart from sonication [52], grinding with glass beads or sand [11,21,41,42] has also been used for disrupting the cells. In general, ammonium sulfate precipitation is also used as a preliminary puri¢cation step.…”

“…For example, potato tuber nuclease, despite its net negative charge at pH 7.5, binds to phosphocellulose due to its a¤nity towards phosphate groups in phosphocellulose [41]. In this manner, this support not only acts as a cation-exchanger but also as an a¤nity matrix.…”

Characterization of Cell-wall-bound Nuclease and Ribonuclease from Potato Tuber

“…9 ) The former had a broad temperature optimum and its optimal temperature was higher than that of cytoplasmic enzyme, 65°C (cell wall) and 55°C (cytoplasmic). The relative molecular masses of the RNase were 36.2 kdal (cell wall) and 19.2 kdal (cytoplasmic). When yeast RNA was used as a substrate, the km's of cell wall and cytoplasmic RNase were 242 and 119 J.1g, respectively.…”

Purification and Some Properties of Plant Endonuclease from Scallion Bulbs

“…To find such a endonuclease, we have investigated several plant sources, and the results on a potato tuber enzyme have been reported. 13 ) In this paper, a procedure for the purification of nuclease from scallion bulbs and some properties of the purified enzyme are described. The enzyme hydrolyzed plasmid pBR322 to small fragments at low enzyme concentrations and has a base preference different from that of nucleases isolated from other plants.…”