Optimization to low temperature activity in psychrophilic enzymes

Psychrophiles, i.e., organisms thriving permanently at near-zero temperatures, synthesize cold-active enzymes to sustain their cell cycle. These enzymes are already used in many biotechnological applications requiring high activity at mild temperatures or fast heat-inactivation rate. Most psychrophilic enzymes optimize a high activity at low temperature at the expense of substrate affinity, therefore reducing the free energy barrier of the transition state. Furthermore, a weak temperature dependence of activity ensures moderate reduction of the catalytic activity in the cold. In these naturally evolved enzymes, the optimization to low temperature activity is reached via destabilization of the structures bearing the active site or by destabilization of the whole molecule. This involves a reduction in the number and strength of all types of weak interactions or the disappearance of stability factors, resulting in improved dynamics of active site residues in the cold. Considering the subtle structural adjustments required for low temperature activity, directed evolution appears to be the most suitable methodology to engineer cold activity in biological catalysts

Therapeutic progress in the control of uncomplicated Plasmodium falciparum malaria

editorial reviewedMalaria is a worldwide public health problem. In Europe, data show an increasing trend of imported cases in the last ten years. Following an alarming observation reporting resistance to anti-malarial drugs, new effective treatments have been developed in early 21st century. These are artemisinin and its derivatives. Artemisinin-based combination therapies (ACT) are now recommended by the World Health Organisation (WHO) since 2006 as the firstline treatment for uncomplicated Plasmodium falciparum malaria. However, resistance phenomena to these new drugs have been described in South-East Asia since 2009. It is thus necessary to use them properly and to monitor their use to preserve their effectiveness in the future