1bs9

Publication Abstract from PubMed

Enzymatic and non-enzymatic iodination of the amino acid tyrosine is a well known phenomenon. The iodination technique has been widely used for labeling proteins. Using high-resolution X-ray crystallographic techniques, the chemical and three-dimensional structures of iodotyrosines formed by non-enzymatic incorporation of I atoms into tyrosine residues of a crystalline protein are described. Acetylxylan esterase (AXE II; 207 amino-acid residues) from Penicillium purpurogenum has substrate specificities towards acetate esters of D-xylopyranose residues in xylan and belongs to a new class of alpha/beta hydrolases. The crystals of the enzyme are highly ordered, tightly packed and diffract to better than sub-angstrom resolution at 85 K. The iodination technique has been utilized to prepare an isomorphous derivative of the AXE II crystal. The structure of the enzyme determined at 1.10 A resolution exclusively by normal and anomalous scattering from I atoms, along with the structure of the iodinated complex at 1.80 A resolution, demonstrate the formation of covalent bonds between I atoms and C atoms at ortho positions to the hydroxyl groups of two tyrosyl moieties, yielding iodotyrosines.

Determination of a protein structure by iodination: the structure of iodinated acetylxylan esterase.,Ghosh D, Erman M, Sawicki M, Lala P, Weeks DR, Li N, Pangborn W, Thiel DJ, Jornvall H, Gutierrez R, Eyzaguirre J Acta Crystallogr D Biol Crystallogr. 1999 Apr;55(Pt 4):779-84. PMID:10089308^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.