A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones.

A simple and efficient method for α-brominating lactones that affords αbromolactones under mild conditions using tetraalkylammonium hydroxide (RNOH) as a base was developed. Lactones are ring-opened with Br and a substoichiometric amount of PBr, leading to good yields of the corresponding α-bromocarboxylic acids. Subsequent intramolecular cyclization over 1 h using a two-phase system (HO/CHCl) containing RNOH afforded α-bromo lactones in good yields.

Recognition of a bulged RNA by peptides derived from the influenza NS1 protein.

A competition assay for RNA binding by the influenza virus NS1 protein using model RNAs, U6-45, corresponding to U6 snRNA revealed that deletion of each of the three bulged-out parts reduced the NS1 protein binding and, in contrast, by deleting all three of the bulged-out parts, simultaneously, and thus producing a double-stranded RNA, the binding was recovered. A common feature of target RNAs of the NS1 protein, U6 snRNA, poly(A) and viral RNA, is the stretch of 'bulged-out' A residues. Thus, the NS1 protein was found to recognize either the stretch of 'bulged-out' A residues or dsRNA which is also a target of the NS1 protein.

Solution structure of an RNA fragment with the P7/P9.0 region and the 3'-terminal guanosine of the tetrahymena group I intron.

In the second step of the two consecutive transesterifications of the self-splicing reaction of the group I intron, the conserved guanosine at the 3' terminus of the intron (omegaG) binds to the guanosine-binding site (GBS) in the intron. In the present study, we designed a 22-nt model RNA (GBS/omegaG) including the GBS and omegaG from the Tetrahymena group I intron, and determined the solution structure by NMR methods. In this structure, omegaG is recognized by the formation of a base triple with the G264 x C311 base pair, and this recognition is stabilized by the stacking interaction between omegaG and C262.