title: N-glycohydrolysis of adenosine diphosphoribosyl arginine linkages by dinitrogenase reductase activating glycohydrolase (activating enzyme) from Rhodospirillum rubrum.
abstract: The reaction catalyzed by the activating enzyme for dinitrogenase reductase from Rhodospirillum rubrum has been studied using an ADP-ribosyl hexapeptide, obtained from proteolysis of inactive dinitrogenase reductase, and synthetic analogs such as N alpha-dansyl-N omega-ADP-ribosylarginine methyl ester. The activating enzyme catalyzed N-glycohydrolysis of the ribosyl-guanidinium linkage releasing ADP-ribose and regenerating an unmodified arginyl guanidinium group. Optimal glycohydrolysis of the low molecular weight substrates occurred at pH 6.6 and required 1 mM MnCl2, but did not require ATP. The ADP-ribosyl hexapeptide (Km 11 microM), N alpha-dansyl-N omega-ADP-ribosylarginine methyl ester (Km 12 microM), N alpha-dansyl-N omega-ADP-ribosylarginine (Km 12 microM), N alpha-dansyl-N omega-1,N6-etheno-ADP-ribosylarginine methyl ester (Km 11 microM), and N alpha-dansyl-N omega-GDP-ribosylarginine methyl ester (Km 11 microM) were comparable substrates. N omega-ADP-ribosylarginine (Km 2 mM) was a poor substrate, and the activating enzyme did not catalyze N-glycohydrolysis of N alpha-dansyl-N omega-5'-phosphoribosylarginine methyl ester or N alpha-dansyl-N omega-ribosylarginine methyl ester. 13C NMR of N alpha-tosyl-N omega-ADP-ribosylarginine methyl ester established that the activating enzyme specifically hydrolyzed the alpha-ribosyl-guanidinium linkage. The beta-linked anomer was hydrolyzed only after anomerization to the alpha configuration. We recommend [arginine(N omega-ADP-alpha-ribose)]dinitrogenase reductase N-glycohydrolase (dinitrogenase reductase activating) and dinitrogenase reductase activating glycohydrolase as the systematic and working names for the activating enzyme.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives / Q000378:metabolism*; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D006026:Glycoside Hydrolases / Q000378:metabolism*; D019791:Guanidine; D006146:Guanidines / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D009699:N-Glycosyl Hydrolases; D009702:Nucleoside Diphosphate Sugars / Q000378:metabolism*; D012247:Rhodospirillum rubrum / Q000201:enzymology*
chemical_list: D006146:Guanidines; D009702:Nucleoside Diphosphate Sugars; C049751:N(alpha)-dansyl-N(omega)-1,N(6)-etheno-ADP-ribosylarginine methyl ester; D000246:Adenosine Diphosphate Ribose; D001120:Arginine; C043357:ADP-ribosylarginine; D006026:Glycoside Hydrolases; D009699:N-Glycosyl Hydrolases; C036091:ADP-ribosyl-(dinitrogen reductase) hydrolase; D019791:Guanidine