Purification and characterization of wheat germ 2',3'-cyclic nucleotide 3'-phosphodiesterase.
The 2',3'-cyclic nucleotide 3'-phosphodiesterase which hydrolyzes nucleoside 2',3'-cyclic phosphates (N greater than p) to nucleoside 2'-phosphates has been purified 16,000-fold to near homogeneity from wheat germ. The purified enzyme is a single polypeptide with a molecular weight of 23,000-24,000. It has a pH optimum of 7.0. The apparent Km values for A greater than p, G greater than p, C greater than p, and U greater than p are 13.1, 9.2, 25.2, and 25.3 mM, respectively. Vmax values for A greater than p, G greater than p, C greater than p, and U greater than p are 2090, 280, 2140, and 600 mumol/min/mg of purified protein, respectively. Wheat germ 2',3'-cyclic nucleotide 3'-phosphodiesterase does not hydrolyze 2',3'-cyclic esters in cyclic phosphate-terminated oligoribonucleotides or in nucleoside 5'-phosphate, 2',3'-cyclic phosphate (pN greater than p). This is in contrast to the 3'-phosphodiesterase activity associated with a wheat germ RNA ligase which hydrolyzes cyclic phosphate-terminated oligonucleotides and pN greater than p substrates much more efficiently than nucleoside 2',3'-cyclic phosphates. The enzyme characterized in this work appears to be the only known 2',3'-cyclic nucleotide 3'-phosphodiesterase specific for 2',3'-cyclic mononucleotides.
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Friedrich Miescher-Institut, Basel, Switzerland.
Kellenberger
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Filipowicz
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D002147:Calmodulin / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D012639:Seeds / Q000201:enzymology*; D013379:Substrate Specificity; D014908:Triticum / Q000201:enzymology
D002147:Calmodulin