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With the aid of structured catalysts and reactors, such as monoliths, solid foams, and 3D printed structures, the limitations of conventional slurry and packed‐bed reactors can be surmounted. Multiphase mathematical models were presented for solid foam structures and the models were verified for the hydrogenation of arabinose, galactose, and xylose to the corresponding sugar alcohols. High product selectivities were obtained in batch and continuous experiments. Three kinetic models were considered: a competitive adsorption model, a semi‐competitive adsorption model as well as a non‐competitive adsorption model for sugar monomers and hydrogen. The models gave a good reproduction of the data, but the semi‐competitive adsorption model was the most plausible one because of the size difference between adsorbed sugar and hydrogen molecules. [ABSTRACT FROM AUTHOR]

A gene coding for a bacterium-type transcription factor, designated Lrs 14, was identified in the genome of the hyperthermophilic archaeon sulfolobus solfataricus. Lrs14 is distantly related to the Lrp -AsnC family of regulators of gene expression in the class Bacteria and has a potential helix-turn-helix motif. Results demonstrate that Lrs14 is a highly thermostable DNA-binding protein and specifically binds to multiple sequences in its own promoter.

The mechanism by which the activity of the active-site mutants Glu387Ala/Gly of the beta-glycosidase from the hyperthermophilic archaeon Sulfolobus solfataricus is restored through addition of external nucleophiles was investigated. Experimental results showed that the beta-glycosidase hydrolyzes beta-glycosides following a retaining mechanism which is dependent on the action of the amino acids Glu387 and Glu206. The type of nucleophile used influences the reaction mechanism behind the restoration process.

A search of the genomes of three white-blooded icefishes and four red-blooded Notothenioidei relatives for the presence of globin-related DNA sequences reveals the hybridization of the alpha-globin probe to red-and white-blooded species genomic DNAs, while hybridzation of the beta-globin probe occurs with only red-blooded species DNAs. The inactive genomic remains of alpha-globin genes are maintained by the ice-fishes, while the beta-globin-encoding gene is lost through rapid mutation or deletion, accounting for the hemoglobinless phenotypes of extant icefishes.

Genetic experiments enable the identification of a gene, which is present immediately upstream of the lacS gene in Sulfolobus solfataricus and the gene codes for a putative membrane proteins, which exhibit homology to the major facilitator superfamily. Eubacteria and eukaryotes have permeases of this family. Identification of an archael member suggests that evolution of the mechanism of secondary transport by the permeases has occurred before the divergence of the three living domains.

The lacS gene encoding a thermostable beta-galactosidase from Sulfolobus solfatiracus was cloned and expressed in Saccharomyces cerevisiae. The cloned gene product and the native protein had the same heat stability and thermophilicity. Inducible protein levels were achieved by fusing the S. solfatiracus gene to the GAL1-CYC1 yeast promoter using galactose as inducer. A promoter for heat shock genes isolated from Caenorhabditis elegans (poly-HSE) also promoted inducible enzyme expression. In this case, the induction was obtained by a temperature shift. Results also suggested that some posttranscriptional event prevented higher expression of the enzyme.

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Mycobacterium tuberculosis O6-methylguanine-DNA methyltransferase (MtOGT) contributes to protect the bacterial GC-rich genome against the pro-mutagenic potential of O6-methylated guanine in DNA. Several strains of M. tuberculosis found worldwide encode a point-mutated O6-methylguanine-DNA methyltransferase (OGT) variant (MtOGT-R37L), which displays an arginine-to-leucine substitution at position 37 of the poorly functionally characterized N-terminal domain of the protein. Although the impact of this mutation on the MtOGT activity has not yet been proved in vivo, we previously demonstrated that a recombinant MtOGT-R37L variant performs a suboptimal alkylated-DNA repair in vitro, suggesting a direct role for the Arg37-bearing region in catalysis. The crystal structure of MtOGT complexed with modified DNA solved in the present study reveals details of the protein-protein and protein-DNA interactions occurring during alkylated-DNA binding, and the protein capability also to host unmodified bases inside the active site, in a fully extrahelical conformation. Our data provide the first experimental picture at the atomic level of a possible mode of assembling three adjacent MtOGT monomers on the same monoalkylated dsDNAmolecule, and disclose the conformational flexibility of discrete regions of MtOGT, including the Arg37-bearing random coil. This peculiar structural plasticity of MtOGT could be instrumental to proper protein clustering at damaged DNA sites, as well as to protein-DNA complexes disassembling on repair. [ABSTRACT FROM AUTHOR]