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Organic–inorganic hybrid phase–transition molecular materials have attracted increasing attention due to their excellent properties of combining inorganic and organic components. However, few research has been conducted on rare‐earth–based bimetallic organic–inorganic hybrids. Here, we successfully constructed a series of rare–earth–based organic–inorganic hybrid multifunctional materials, (C6H14N2)2EuX(NO3)6O2 (X=Na, K, Rb), with reversible phase transition, switchable dielectric, photoluminescence and semiconductor properties. Specifically, the phase‐transition temperature of three compounds are determined to be 364, 405 and 440 K, respectively. By the confinement effect caused by the variation of alkali metal elements in the two–dimensional structure, the phase transition temperature is successfully increased by 76 K. Meanwhile, the solid–state photoluminescence of three compounds displays bright red light at room temperature. Additionally, the bandgaps of three compounds are determined to be 3.21, 3.53 and 3.32 eV, respectively. It is expected that the strategy of alkali metal substitution proposed in this work will provide new thoughts for the design of multifunctional organic‐inorganic hybrid crystals. [ABSTRACT FROM AUTHOR]

Bacterial tRNA (guanine37-N1)-methyltransferase (TrmD) plays important roles in translation, making it an important target for the development of new antibacterial compounds. TrmD comprises two domains with the N-terminal domain binding to the S-adenosyl-l-methionine (SAM) cofactor and the C-terminal domain critical for tRNA binding. Bacterial TrmD is functional as a dimer. Here we report the backbone NMR resonance assignments for the full length TrmD protein of Pseudomonas aeruginosa. Most resonances were assigned and the secondary structure for each amino acid was determined according to the assigned backbone resonances. The availability of the assignment will be valuable for exploring molecular interactions of TrmD with ligands, inhibitors and tRNA. [ABSTRACT FROM AUTHOR]

Bacterial tRNA (guanine37-N1)-methyltransferase (TrmD) is an important antibacterial target due to its essential role in translation. TrmD has two domains connected with a flexible linker. The N-terminal domain (NTD) of TrmD contains the S-adenosyl-l-methionine (SAM) cofactor binding site and the C-terminal domain is critical for tRNA binding. Here we report the backbone NMR resonance assignments for NTD of Pseudomonas aeruginosa TrmD. Its secondary structure was determined based on the assigned resonances. Relaxation analysis revealed that NTD existed as dimers in solution. NTD also exhibited thermal stability in solution. Its interactions with SAM and other compounds suggest it can be used for evaluating SAM competitive inhibitors by NMR. [ABSTRACT FROM AUTHOR]

Pre-, peri-, and postoperative oral administration of branched-chain amino acids (BCAA) to patients with primary liver cancer (PLC) during hepatic resection (HR) remains controversial. The aim of this systematic review was to evaluate the efficacy and safety of this practice. Seven literature databases were systematically searched for randomized controlled trials (RCTs) that reported pre-, peri-, and postoperative oral administration of BCAA for PLC patients during HR. Three RCTs were included in a meta-analysis in which risk ratios (RRs) and 95% confidence intervals (95% CIs) were calculated. The 2 groups showed similar recurrence rates (RR = 1.03, 95% CI 0.78 to 1.36) and similar overall survival (RR = 0.91, 95% CI 0.71 to 1.18). Adverse events related to oral administration of BCAA were more than the control group, including nausea, vomiting, diarrhea, abdominal distension, abdominal pain, and hypertension. However, all adverse reactions disappeared after symptomatic treatment. The available evidence suggests that although pre-, peri-, and postoperative oral BCAA for patients with PLC is safe, it is of questionable clinical value. More RCTs are warranted to explore this question definitively. [ABSTRACT FROM PUBLISHER]

The phosphotransfer mechanism of PYKs (pyruvate kinases) has been studied in detail, but the mechanism of the intrinsic decarboxylase reaction catalysed by PYKs is still unknown. 1H NMR was used in the present study to follow OAA (oxaloacetate) decarboxylation by trypanosomatid and human PYKs confirming that the decarboxylase activity is conserved across distantly related species. Crystal structures of TbPYK (Trypanosoma brucei PYK) complexed with the product of the decarboxylase reaction (pyruvate), and a series of substrate analogues (D-malate, 2-oxoglutarate and oxalate) show that the OAA analogues bind to the kinase active site with similar binding modes, confirming that both decarboxylase and kinase activities share a common site for substrate binding and catalysis. Decarboxylation of OAA as monitored by NMRfor TbPYK has a relatively low turnover with values of 0.86 s-¹ and 1.47 s-1 in the absence and presence of F26BP (fructose 2,6-bisphosphate) respectively. Human M1PYK (M1 isoform of PYK) has a measured turnover value of 0.50 s-1. The X-ray structures explain why the decarboxylation activity is specific for OAA and is not general for a-oxo acid analogues. Conservation of the decarboxylase reaction across divergent species is a consequence of piggybacking on the conserved kinase mechanism which requires a stabilized enol intermediate. [ABSTRACT FROM AUTHOR]

The active site of pyruvate kinase (PYK) is located between the AC core of the enzyme and a mobile lid corresponding to domain B. Many PYK structures have already been determined, but the first `effector-only' structure and the first with PEP (the true natural substrate) are now reported for the enzyme from Trypanosoma brucei. PEP soaked into crystals of the enzyme with bound allosteric activator fructose 2,6-bisphosphate (F26BP) and Mg2+ triggers a substantial 23° rotation of the B domain ` in crystallo', resulting in a partially closed active site. The interplay of side chains with Mg2+ and PEP may explain the mechanism of the domain movement. Furthermore, it is apparent that when F26BP is present but PEP is absent Mg2+ occupies a position that is distinct from the two canonical Mg2+-binding sites at the active site. This third site is adjacent to the active site and involves the same amino-acid side chains as in canonical site 1 but in altered orientations. Site 3 acts to sequester Mg2+ in a `priming' position such that the enzyme is maintained in its R-state conformation. In this way, Mg2+ cooperates with F26BP to ensure that the enzyme is in a conformation that has a high affinity for the substrate. [ABSTRACT FROM AUTHOR]