The ribosome catalyzes two fundamental biological reactions: peptidyl transfer, the formation of a peptide bond during protein synthesis, and peptidyl hydrolysis, the release of the complete protein from the peptidyl tRNA upon completion of translation. The ribosome is able to utilize and distinguish the two different nucleophiles for each reaction, the α-amine of the incoming aminoacyl tRNA versus the water molecule. The correct binding of substrates induces structural rearrangements of ribosomal active-site residues and the substrates themselves, resulting in an orientation suitable for catalysis. In addition, active-site residues appear to provide further assistance by ordering active-site water molecules and providing an electrostatic environment via a hydrogen network that stabilizes the reaction intermediates and possibly shuttles protons. Major questions remain concerning the timing, components, and mechanism of the proton transfer steps. This review summarizes the recent progress in structural, biochemical, and computational advances and presents the current mechanistic models for these two reactions.

A lthough sleep is critical to patient recovery in the hospital, hospitalization is not restful, 1,2 and inpatient sleep deprivation has been linked to poor health outcomes. 1-4 The American Academy of Nursing's Choosing Wisely ® campaign recommends nurses reduce unnecessary nocturnal care. 5 However, interventions to improve inpatient sleep are not widely implemented. 6 Targeting routine disruptions, such as overnight vital signs, by changing default settings in the electronic health record (EHR) with "nudges" could be a cost-effective strategy to improve inpatient sleep. 4,7 We created Sleep for Inpatients: Empowering Staff to Act (SI-ESTA), which pairs nudges in the EHR with interprofessional education and empowerment, 8 and tested its effectiveness on objectively and subjectively measured nocturnal sleep disruptors. METHODS Study Design Two 18-room University of Chicago Medicine general-medicine units were used in this prospective study. The SIESTA-enhanced unit underwent the full sleep intervention: nursing education and empowerment, physician education, and EHR changes. The standard unit did not receive nursing interventions but received all other forms of intervention. Because physicians simultaneously cared for patients on both units, all internal medicine residents and hospitalists received the same education. The study population included physicians, nurses, and awake English-speaking patients who were cognitively intact and admitted to these two units. The University of Chicago Institutional Review Board approved this study (12-1766; 16685B).

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Much interest has focused on the mechanisms of the five naturally occurring self-cleaving ribozymes, which, in spite of catalyzing the same reaction, adopt divergent strategies. These ribozymes, with the exception of the recently described glmS ribozyme, do not absolutely require divalent metal ions for their catalytic chemistries in vitro. A mechanistic investigation of an in vitro-selected, RNA-cleaving DNA enzyme, the bipartite, which catalyzes the same chemistry as the five natural self-cleaving ribozymes, found a mechanism of significant complexity. The DNAzyme showed a bell-shaped pH profile. A dissection of metal usage indicated the involvement of two catalytically relevant magnesium ions for optimal activity. The DNAzyme was able to utilize manganese(II) as well as magnesium; however, with manganese it appeared to function complexed to either one or two of those cations. Titration with hexaamminecobalt(III) chloride inhibited the activity of the bipartite; this suggests that it is a metalloenzyme that utilizes metal hydroxide as a general base for activation of its nucleophile. Overall, the bipartite DNAzyme appeared to be kinetically distinct not only from the self-cleaving ribozymes but also from other in vitro-selected, RNA-cleaving deoxyribozymes, such as the 8-17, 10-23, and 614.

The importance of genetic ancestry characterization is increasing in genomic implementation efforts, and clinical pharmacogenomic guidelines are being published that include populationspecific recommendations. Our aim was to test the ability of focused clinical pharmacogenomic SNP panels to estimate individual genetic ancestry (IGA) and implement population-specific