CBCHFX 14 (4) 401 – 524 (2013) · ISSN 1439-4227 · Vol. 14 · No. 4 · March 2013 D55712

4/2013

www.chembiochem.org

Highlight: A Unified Model for Ferritin Iron Loadingby the Catalytic Center (R. K. Watt)

Original contributions: Amino Acid-Specific Labelingof Multidomain Proteins (F. H.-T. Allain)

Resin Acid Conversion with CYP105A1 (R. Bernhardt)

A Journal of

Cover Picture

Nicole Timms, Claire L. Windle, Anna Polyakova, James R. Ault,Chi H. Trinh, Arwen R. Pearson, Adam Nelson, and Alan Berry*

The cover picture shows an artist’s impression of the substrate approaching the (b/a)8-barrel enzyme, N-acetylneuraminic acid lyase engineered to contain an unnatural aminoacid in the active site. The unnatural amino acid, thialysine (highlighted), is introducedby chemical modification. On p. 474 ff. , A. Berry et al. explain how X-ray structuralstudies and kinetic characterization show that the unnatural amino acid mimics theshape and positioning of the natural lysine at this site, but lower activity is regainedbecause of the difference in the pKa of thialysine compared to lysine. The study opensthe way to tailored novel enzymes containing unnatural amino acids.