@article{ccd562cb31234930a80c96fed2b3bf6c,
title = "A Modified Uridine in the Anticodon of E. Coli",
abstract = "The anticodon of an ochre-suppressing derivative of E. coli tRNATyrL, previously identified as UUA, can contain a modified uridlne (U+) in the first position. The novel modified nudeotide has been identified by twodimensional thin layer chromatography following RNase T2 digestion of anticodon contalnlng fragments. U+R is found in less than stolchiometric molar yields in preparations of tRNATyrL Su+Oc. The electrophoretlc mobility of U+P is the same as Up at pH 3.5 and PH 7.5. U+ probably does not contain sulfur since it cannot be labeled with 35S in vivo incorporation experiments.",
author = "S. Altman",
note = "Funding Information: ochre-suppressing tRNA was derived by a one step mutation of an amber-suppressing derivative (anticodon: CUA) of tRNATy'r su+. A2 and since no other U (aside from t|>) is found modified in the anticodon fragment, we may assume that the novel modified uridine is in the first position of the anticodon, i.e. U UA. In the electrophoresls system previously used (10) to analyze this anticodon, Up comigrates with Up and is therefore undetectable. The molar yields of the modified nudeotide are variable and usually low, about 0.3 moles per mole of the ochre-suppressing tRNA. Preparations of Up from an E_. coll strain bearing the relaxed phenotype gave consistently higher yields than preparations from strains with the stringent phenotype. Thus, the low molar yields of Up are probably not solely due to intrinsic lability of the modifying group. The low level of modification may be a reflection of the overburdening of host cell modification enzymes by the amplification of the tRNA gene following infection with the transducing phage. On the other hand, the mutated tRNATy. r may not be a substrate which can be used efficiently under any conditions by modification enzymes normally interacting with other tRNA substrates. This latter hypothesis is supported by the results of genetic",
year = "1976",
month = feb,
doi = "10.1093/nar/3.2.441",
language = "English (US)",
volume = "3",
pages = "441--448",
journal = "Nucleic Acids Research",
issn = "0305-1048",
publisher = "Oxford University Press",
number = "2",
}