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| Phosphorylation of Coformycin and 2 -Deoxycoformycin, and Substrate and Inhibitor Properties of the Nucleosides and Nucleotides in Several Enzyme Systems  | | | | Abstract
| Under conditions where 2'-deoxycoformycin is enzymatically phosphorylated by wheat shoot phosphotransferase to the 5'-phosphate in 15—20% yield, coformycin is a relatively poor sub strate, and is phosphorylated only to the extent of < 5%. However, chemical phosphorylation of coformycin by modifications of the Yoshikawa procedure led to isolation of coformycin-5'-phos phate in 20% overall yield. Coformycin-5'-phosphate was characterized by various criteria, including 'H NMR spectro scopy. Comparison of the spectrum with that of the parent nucleoside indicated that the nu cleotide is predominantly, although not exclusively, in the conformation anti about the glycosidic bond. Like 2'-deoxycoformycin-5'-phosphate, coformycin-5'-phosphate was a feeble substrate of snake venom 5'-nucleotidase, and is hydrolyzed, quantitatively, at only 2% the rate for 5'-AMP. With 5'-AMP analogues as substrate, the 5'-phosphates of both coformycin and deoxycoformycin were poor inhibitors of the enzyme, with K, values > 0.3 mM. The 5'-phosphates of both coformycin and deoxycoformycin do not significantly inhibit adenosine deaminase (K} > 0.2 m M), but are potent inhibitors of adenylate deaminase (Kj < 10"9 m). Neither coformycin nor deoxycoformycin are inhibitors of mammalian purine nucleoside phosphorylase. The stabilities of coformycin, deoxycoformycin, and their 5'-phosphates, have been examined as a function of pH, and nature of the buffer medium. In particular, all exhibit instability in acid and neutral media, but are relatively stable in the vicinity of pH 9. Some biological aspects of the overall results are presented. | | | |
Reference
| Z. Naturforsch. 40c, 710—714 (1985); received March 5/June 3 1985 | | | |
Published
| 1985 | | | |
Keywords
| Coformycin, 2'-Deoxycoformycin, Phosphorylation, 5'-Phosphates, Substrates, Inhibitors | | | |
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| default:Reihe_C/40/ZNC-1985-40c-0710.pdf | | | | Identifier
| ZNC-1985-40c-0710 | | | | Volume
| 40 | |
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