Isolation and physiochemical properties of an adenosine-rich gluten fraction

Gluten proteins were isolated from the 0.01 mol acetic acid extract of bread. It was observed that precipitation of gluten provoked by 200 mM NaCl could partly be inhibited by adenosine. Based on this finding a method for isolation of the gluten fraction resisting saline precipitation in the presence of adenosine was elaborated. This fraction termed by us gluten-A-S, was found to have a lower glutamine + glutaminic acid and a higher proline and phenylalanine content than gluten. By sodium dodecylsulphate polyacrylamide gel electrophoresis gluten-A-S was shown to contain components of 58 000 and 34 000 dalton molecular weight after mercaptoethanol treatment while without the latter it contained a component of 74 000 dalton. The absorption maximum of the compound is at 260 mm; E280nm/E260nm = 0.5. In accordance with previous findings, gluten-A-S was found to contain 50-100 nmol adenosine per mg protein in a strong binding. It seems that in addition to the small amount of tightly bound adenosine, gluten-A-S contains a larger quantity of adenosine loosely bound to the protein. The physiological effects of dissociable adenosine bound to gluten and its possible role in the pathomechanism of gluten sensitive enteropathy is discussed in detail.