M. Soriano-Garcia is the first-listed author of a structural study connecting calcium ion binding with organization of the Gla domain of prothrombin. The 1992 paper reports an X-ray crystallography structure of calcium-bound prothrombin fragment1 at resolution and lists a chemistry affiliation at Michigan State University.[ref]
The comparison was mechanistically informative. In crystals without bound calcium, much of the Gla domain was disordered; in the calcium-bound preparation, the domain was well resolved and bound seven calcium ions. Carboxylate groups of gamma-carboxyglutamate residues helped coordinate those ions. Thus calcium was associated with a particular folded arrangement, rather than simply being another ingredient in solution.[ref]
The Ca2+ ion and membrane binding structure of the Gla domain of Ca-prothrombin fragment 1 by M. Soriano-Garcia and others. Abstract: apo/calcium-bound comparison and coordination
The study illustrates a limit of structural interpretation. Failure to resolve a region in a crystal does not prove that the corresponding amino acids are absent. The same sequence can be present while adopting multiple arrangements that do not yield one sharply defined crystallographic position. Comparing binding states can therefore reveal organization without implying that a missing part of the image was missing from the protein.
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