Mung bean nuclease I. Physical, chemical, and catalytic properties.
A simplified purification procedure for mung bean nuclease has been developed yielding a stable enzyme that is homogeneous in regards to shape and size. The nuclease is a glycoprotein consisting of 29% carbohydrate by weight. It has a molecular weight of 39 000 as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The enzyme contains 1 sulfhydryl group and 3 disulfide bonds per molecule. It has a high content (12.6 mol %) of aromatic residues. Approximately 70% of the enzyme molecules contain a peptide bond cleavage at a single region in the protein. The two polypeptides, 25 000 and 15 000 daltons, are covalently linked by a disulfide bond(s). Both the cleaved and intact forms of the enzyme are equally active in the hydrolysis of the phosphate ester linkages in either DNA, RNA, or adenosine 3'-monophophate. The enzymatic activity of mung bean nuclease can be stabilized at pH 5 in the presence of 0.1 mM zinc acetate, 1.0 mM cysteine, and 0.001% Triton X-100. The enzyme can be inactivated and reactivated by the removal and readdition of Zn2+ or sulfhydryl compounds.
D000596:Amino Acids / Q000032:analysis; D002413:Cations, Divalent; D003851:Deoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism; D004220:Disulfides / Q000032:analysis; D004355:Drug Stability; D004492:Edetic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D010744:Phosphoric Monoester Hydrolases / Q000302:isolation & purification / Q000378:metabolism; D010944:Plants / Q000201:enzymology*; D012260:Ribonucleases / Q000302:isolation & purification / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013438:Sulfhydryl Compounds / Q000032:analysis; D015032:Zinc / Q000494:pharmacology
D000596:Amino Acids; D002413:Cations, Divalent; D004220:Disulfides; D013438:Sulfhydryl Compounds; D004492:Edetic Acid; D003851:Deoxyribonucleases; D012260:Ribonucleases; D010744:Phosphoric Monoester Hydrolases; D015032:Zinc