Thematic minireview series: metals in biology 2013.

One-half of the available protein structures contain metals, explaining their roles as essential trace elements. Metals are also critical in many aspects of nucleic acid biochemistry. This prologue briefly introduces the fifth of the Thematic Series on Metals in Biology, which began in the Journal of Biological Chemistry in 2009. The five minireviews in this 2013 series deal with the molybdenum prosthetic group (a pterin known as Moco); the biosynthesis of the "M-cluster" molybdenum prosthetic group of nitrogenase; the biosynthesis of the nickel-based metallocenter of the enzyme urease; several of the processing, transport, and medical aspects of cobalamins; and the growing roles of heme sensor proteins.