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“The last step in eukaryotic translational initiation involves the joining of the large and small subunits of the ribosome, with initiator transfer RNA (Met-tRNA(i)(Met)) positioned over the start codon of messenger RNA in the P site. This step is catalyzed by initiation factor eIF5B. We used recent advances

in cryo-electron microscopy (cryo-EM) to determine a structure of the eIF5B PS-341 order initiation complex to 6.6 angstrom resolution from <3% of the population, comprising just 5143 particles. The structure reveals conformational changes in eIF5B, initiator tRNA, and the ribosome that provide insights into the role of eIF5B in translational initiation. The relatively high resolution obtained from such a small fraction of a heterogeneous sample suggests a general approach for characterizing the structure of other dynamic or transient biological complexes.”
“Cytochrome P450 enzymes activate oxygen at heme iron centers

to oxidize relatively inert substrate carbon-hydrogen bonds. Cysteine thiolate coordination to iron is posited to increase the pK(a) (where K-a is the acid dissociation constant) of compound II, an iron(IV)hydroxide complex, correspondingly lowering the one-electron reduction potential of compound I, the active catalytic intermediate, and decreasing the driving force for deleterious auto-oxidation of tyrosine and tryptophan residues in the enzyme’s framework. Here, we report on the preparation of an iron(IV) hydroxide complex in a P450 enzyme (CYP158) in >= 90% yield. Using rapid mixing technologies in conjunction Hippo pathway inhibitor with Mossbauer, ultraviolet/visible, and x-ray absorption spectroscopies, CRT0066101 nmr we determine a pK(a) value for this compound of 11.9. Marcus theory analysis indicates that this elevated pK(a) results in a >10,000-fold reduction in the rate constant for oxidations of the protein framework, making these processes noncompetitive with substrate oxidation.”
“Quantum memories capable of storing and retrieving

coherent information for extended times at room temperature would enable a host of new technologies. Electron and nuclear spin qubits using shallow neutral donors in semiconductors have been studied extensively but are limited to low temperatures (less than or similar to 10 kelvin); however, the nuclear spins of ionized donors have the potential for high-temperature operation. We used optical methods and dynamical decoupling to realize this potential for an ensemble of phosphorous-31 donors in isotopically purified silicon-28 and observed a room-temperature coherence time of over 39 minutes. We further showed that a coherent spin superposition can be cycled from 4.2 kelvin to room temperature and back, and we report a cryogenic coherence time of 3 hours in the same system.”
“The performance of optimized graphene devices is ultimately determined by the quality of the graphene itself.