title: Double-stranded RNA-stimulated enzyme activities isolated from human placental extracts.
abstract: A (2'-5')An synthetase activity was isolated from human placental extracts by affinity chromatography on poly(rI) . poly(rC)-agarose. The oligonucleotide (2'-5')An was identified by (1) chromatography on PEI-cellulose and DEAE-cellulose, (2) inhibition of polypeptide synthesis in lysed rabbit reticulocytes (3) competition of the binding of pppA(pA)3,3'-[32P]pCp to rabbit reticulocyte lysates, and (4) alkaline phosphatase digestion. The synthetase activity in most placental preparations is activated by natural or synthetic dsRNA. However, in a few placental synthetase preparations, dsRNA is only marginally stimulatory and only becomes effective by prior treatment of the enzyme preparations with the calcium-dependent micrococcal nuclease. This suggests that there is an endogenous placental dsRNA contaminant in the enzyme preparations. In some synthetase preparations, a second dsRNA-stimulated product, tentatively identified as the nucleotide 5'-IMP, is also observed. Because the specific AMP deaminase inhibitor coformycin (10 microM) blocks the formation of IMP from ATP and causes a quantitative accumulation of AMP, and because the formation of IMp becomes independent of dsRNA when ADP or AMP is used in place of ATP, the presence of a dsRNA-stimulated ATP phosphohydrolase (ATPase) activity in human placenta is suggested.
mesh_terms: D015088:2',5'-Oligoadenylate Synthetase / Q000302:isolation & purification* / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D003070:Coformycin / Q000494:pharmacology; D005260:Female; D006801:Humans; D007291:Inosine Monophosphate / Q000378:metabolism; D007700:Kinetics; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D012330:RNA, Double-Stranded / Q000494:pharmacology*
chemical_list: D012330:RNA, Double-Stranded; D003070:Coformycin; D007291:Inosine Monophosphate; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D015088:2',5'-Oligoadenylate Synthetase