title: Reverse action of ribonuclease T1 in frozen aqueous systems.
abstract: We have studied ribonuclease T1 (EC 3.1-27.3)-catalysed synthesis of guanylyl-(3'-->5')cytidine in frozen aqueous reaction mixtures at -10 degrees C and in solution at 0 degree C in order to investigate whether ribonuclease-catalysed synthetic reactions can take advantage of the yield-increasing effect of freezing as was reported for protease-catalysed peptide synthesis. Under frozen state conditions, substantially increased yields of GpC were obtained compared to the reactions in solution. From the fact that no irreversible hydrolysis of the 2'3'-cyclic donor was observed it can be concluded that transesterification of the newly formed phosphodiester bond is the most important yield-limiting factor in ribonuclease T1-catalysed dinucleoside phosphate synthesis.
authors.affiliation: Leipzig University, Faculty of Biosciences, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Haensler
authors.forename: U
authors.initials: U
authors.lastname: Hahn
authors.forename: H D
authors.initials: HD
authors.lastname: Jakubke
mesh_terms: D015226:Dinucleoside Phosphates / Q000096:biosynthesis*; D005615:Freezing; D007700:Kinetics; D006163:Ribonuclease T1 / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000737:chemistry*
chemical_list: D015226:Dinucleoside Phosphates; D014867:Water; C004804:guanylyl-(3',5')-cytidine; D006163:Ribonuclease T1