The ineluctable requirement for the trans-iron elements molybdenum and/or tungsten in the origin of life #chempaperaday 271

An evolutionary tree of key enzymes from the Complex-Iron-Sulfur-Molybdoenzyme (CISM) superfamily distinguishes “ancient” members, i.e. enzymes present already in the last universal common ancestor (LUCA) of prokaryotes, from more recently evolved subfamilies. The majority of the presented subfamilies and, as a consequence, the Molybdo-enzyme superfamily as a whole, appear to have existed in LUCA.

I believe many people know that some enzymes have molybdenum cofactors. But, I highly doubt that many are aware of the fact that tungsten can also be found in some enzymes. Which one came first though? What are the differences between them in terms of solubility for example? The real interesting part is that both molybdenum and tungsten are produced in supernova explosions. So when did they come? How did they come here? how did they affect the life on earth? Well not all the answers are known yet, but here is a nice paper on molybdenum and tungsten enzymes.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3278043/

Elements and Evolution #chempaperaday 270

Changes in elemental abundances in Earth's oceans on geological time scales are intimately linked to evolutionary processes.

 The concentrations of metal ions in the oceans (and in the earth's crust)  have changed dramatically since the beginning. It is clear that they assisted the life on earth. All these are also tied to atmospheric conditions such as the concentration of certain gases and the temperature. 

If you are into evolution and the elements' effects on it, this is a good start.

http://science.sciencemag.org/content/322/5907/1481

Redox bifurcations: Mechanisms and importance to life now, and at its origin #chempaperaday 269

Some of the biological reactions don't really make sense in terms of redox chemistry. Most of the time, these reactions occur because they are catalyzed by enzymes or coupled to other mechanism. Here is an interesting Commentary about these processes and how they approach the the topic. Worth reading.

http://onlinelibrary.wiley.com/doi/10.1002/bies.201100134/abstract