Cover Picture: ChemBioEng Reviews 3/2015

Abstract Four Types of Phytases Phytate is the major storage form of phosphorus in plant seed. It is an anti‐nutrient substance in animal feed due to the lack of digestive enzyme in monogastric animals. Although the phosphorus deficiency could be compensated by adding inorganic phosphorus, excessive phosphorus has caused environmental pollution. By using microbial phytases as animal feed additives, phytate can be hydrolyzed to liberate phosphate and both problems can be solved ingeniously. Nowadays, as one of the most important eco‐friendly enzyme products in global market, phytases have been studied extensively for the molecular mechanisms and for protein engineering to produce more powerful enzymes. Here the complex crystal structures of Escherichia coli histidine acid phosphatase (blue), Bacillus subtilis β‐propeller phytase (orange) and Selenomonas ruminantium protein tyrosine phosphatase‐like phytase (green) are shown, along with a model of soybean purple acid phosphatase (magenta).