Current State of [Fe]-Hydrogenase and Its Biomimetic Models.

[Fe]-hydrogenase, the third type of natural hydrogenase, is capable to heterolytically activate hydrogen molecule and transfer the resulting hydride to an unsaturated substrate, making it a promising hydrogenation catalyst. Over the last three decades, fruitful results on this enzyme have been achieved. In this review, we have summarized the major progresses about this enzyme including its structural characterisation, catalytic mechanism, cofactor biosynthesis, mimetic model development as well as artificial enzymes construction. In the meanwhile, challenges and opportunities of this enzyme and its mimetic systems in the application of synthetic chemistry and others are discussed.

[Advances of structure, function, and catalytic mechanism of methyl-coenzyme M reductase].

Methanogens are unique microorganisms for methane production and the main contributor of the biogenic methane in atmosphere. Methyl-coenzyme M reductase (Mcr) catalyzes the last step of methane production in methanogenesis and the first step of methane activation in anaerobic oxidation of methane. The genes encoding this enzyme are highly conserved and are widely used as a marker in the identification and phylogenetic study of archaea. There has been a longstanding interest in its unique cofactor F430 and the underpinning mechanisms of enzymatic cleavage of alkane C-H bond. The recent breakthroughs of high-resolution protein and catalytic-transition-state structures further advanced the structure-function study of Mcr. In particular, the recent discovery of methyl-coenzyme M reductase-like (Mcr-like) enzymes that activates the anaerobic degradation of non-methane alkanes has attracted much interest in the molecular mechanisms of C-H activation without oxygen. This review summarized the advances on function-structure-mechanism study of Mcr/Mcr-like enzymes. Additionally, future directions in anaerobic oxidation of alkanes and greenhouse-gas control using Mcr/Mcr-like enzymes were proposed.

Characteristics of the mitochondrial genome of Rana omeimontis and related species in Ranidae: Gene rearrangements and phylogenetic relationships.

The Omei wood frog (Rana omeimontis), endemic to central China, belongs to the family Ranidae. In this study, we achieved detail knowledge about the mitogenome of the species. The length of the genome is 20,120 bp, including 13 protein-coding genes (PCGs), 22 tRNA genes, two rRNA genes, and a noncoding control region. Similar to other amphibians, we found that only nine genes (ND6 and eight tRNA genes) are encoded on the light strand (L) and other genes on the heavy strand (H). Totally, The base composition of the mitochondrial genome included 27.29% A, 28.85% T, 28.87% C, and 15.00% G, respectively. The control regions among the Rana species were found to exhibit rich genetic variability and A + T content. R. omeimontis was clustered together with R. chaochiaoensis in phylogenetic tree. Compared to R. amurensis and R. kunyuensi, it was more closely related to R. chaochiaoensis, and a new way of gene rearrangement (ND6-trnE-Cytb-D-loop-trnL2 (CUN)-ND5-D-loop) was also found in the mitogenome of R. amurensis and R. kunyuensi. Our results about the mitochondrial genome of R. omeimontis will contribute to the future studies on phylogenetic relationship and the taxonomic status of Rana and related Ranidae species.