Publications

• Plant purine nucleoside catabolism employs a guanosine deaminase required for the generation of xanthosine in Arabidopsis.

  Dahncke K., Witte C.P.

  Purine nucleotide catabolism is common to most organisms and involves a guanine deaminase to convert guanine to xanthine in animals, invertebrates, and microorganisms. Using metabolomic analysis of mutants, we demonstrate that Arabidopsis thaliana uses an alternative catabolic route employing a hi ... >> More

  Purine nucleotide catabolism is common to most organisms and involves a guanine deaminase to convert guanine to xanthine in animals, invertebrates, and microorganisms. Using metabolomic analysis of mutants, we demonstrate that Arabidopsis thaliana uses an alternative catabolic route employing a highly specific guanosine deaminase (GSDA) not reported from any organism so far. The enzyme is ubiquitously expressed and deaminates exclusively guanosine and 2'-deoxyguanosine but no other aminated purines, pyrimidines, or pterines. GSDA belongs to the cytidine/deoxycytidylate deaminase family of proteins together with a deaminase involved in riboflavin biosynthesis, the chloroplastic tRNA adenosine deaminase Arg and a predicted tRNA-specific adenosine deaminase 2 in A. thaliana. GSDA is conserved in plants, including the moss Physcomitrella patens, but is absent in the algae and outside the plant kingdom. Our data show that xanthosine is exclusively generated through the deamination of guanosine by GSDA in A. thaliana, excluding other possible sources like the dephosphorylation of xanthosine monophosphate. Like the nucleoside hydrolases NUCLEOSIDE HYDROLASE1 (NSH1) and NSH2, GSDA is located in the cytosol, indicating that GMP catabolism to xanthine proceeds in a mostly cytosolic pathway via guanosine and xanthosine. Possible implications for the biosynthetic route of purine alkaloids (caffeine and theobromine) and ureides in other plants are discussed. << Less

  Plant Cell 25:4101-4109(2013) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Properties of peptidylarginine deiminase from the epidermis of newborn rats.

  Fujisaki M., Sugawara K.

  An enzyme which catalyzes the coversion of arginyl residues to citrullyl residues in protein was obtained from the extract of the epidermis of newborn rats. The enzyme required Ca2+ for its activity. The enzyme activity was enhanced in the presence of DTT. The maximum activity was observed at pH 7 ... >> More

  An enzyme which catalyzes the coversion of arginyl residues to citrullyl residues in protein was obtained from the extract of the epidermis of newborn rats. The enzyme required Ca2+ for its activity. The enzyme activity was enhanced in the presence of DTT. The maximum activity was observed at pH 7.5 at 50 degrees C in the presence of 10 mm CaCl2 and 2 mM DTT. The activity was inhibited strongly by treatment of the enzyme with monoiodoacetate or PCMB, which suggests that the epidermal enzyme is an SH-enzyme. The molecular weight of the enzyme was calculated by gel filtration to be about 48,000. It was essential for the alpha-amino or alpha-carboxyl group of the L-arginine substrate to be involved in a peptide linkage. The enzyme showed marked activities towards N-substituted L-arginine derivatives such as BZ-L-Arg, BZ-L-Arg-NH2, and BZ-Gly-L-Arg, But the action of the enzyme on free L-arginine was negligible. The enzyme activity was affected by the nature of the residue neighboring the arginyl residue in proteins. The authors propose the name "peptidylarginine deiminase" for this enzyme. A considerable specificity of the enzyme for proteins from the epidermal cells in terminal differentiation was observed. The results suggest that citrullyl residues in membranous protein of horny cells of the epidermis of newborn rat are formed by the action of epidermal peptidylarginine deiminase. << Less

  J Biochem 89:257-263(1981) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.