Publication Abstract from PubMed
Using heavily methionine-substituted T4 lysozyme as an example, it is shown how the addition or deletion of a small number of methionines can simplify the location of selenium sites for use in MAD phasing. By comparing the X-ray data for a large number of singly substituted lysozymes, it is shown that the optimal amino acid to be substituted by methionine is leucine, followed, in order of preference, by phenylalanine, isoleucine and valine. The identification of leucine as the first choice agrees with the ranking suggested by the Dayhoff mutation probability, i.e. by the frequency of amino-acid substitutions in the sequences of related proteins. The ranking of the second and subsequent choices, however, differ significantly.
Use of differentially substituted selenomethionine proteins in X-ray structure determination.,Gassner NC, Matthews BW Acta Crystallogr D Biol Crystallogr. 1999 Dec;55(Pt 12):1967-70. PMID:10666571[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
