Marie N. Lipsett

The behavior of 4-thiouridine in the E.coli s-RNA molecule

Abstract A study has been made of the state of the sulfur-containing nucleotide, 4-thiouridine, in the s-RNA from E. coli . The evidence gathered from titration and denaturation studies indicates that this base is present in hydrogen-bonded form in normal E. coli s-RNA.

The isolation of a 4-thiouridine-containing disulfide from oxidized Escherichia coli tRNA is not artifactual

Abstract Iodine-oxidized Escherichia coli tRNA yields an oxidized 4-thiouridine dinucleoside after enzymatic digestion and dephosphorylation. The original isolation has been questioned on the basis of an observed instability of 4-thiouridine disulfide in Tris-Cl buffer and a persistent oxidizing capacity of some resins after exposure to iodine. It is here pointed out that the original isolation specifically negated both of these objections. The fragment recently isolated by Kaiser ( Arch. Biochem. Biophys. 183 , 421–431, 1977) appears to be very similar to the one previously reported, although probably neither one is the symmetrical 4-thiouridine disulfide.