Effect of a calcium-binding gluten fraction on the superprecipitation of actomyosin.

The Ca2+-binding gluten fraction isolated by the authors has been shown to prolong the clearing phase and to shorten the physiological contraction phase of ATP activated natural actomyosin suspension in the presence of physiological potassium chloride in a dose dependent manner. The mean ATPase activity of myosin and actomyosin was calculated for each phase from the actual ATP concentrations, measured at 30 sec intervals, and from the phase lengths. The preparation was found markedly to inhibit the ATPase activity during the clearing and physiological contraction phase. Since both myosin and actomyosin ATPase is Ca2+-dependent, it is assumed that the inhibitory effect of the gluten fraction on ATPase activity may be mediated by its free Ca2+-binding capacity, resulting in modified phase lengths of actomyosin superprecipitation. On the basis of these experimental results a hypothesis is put forward of the part of the Ca2+-binding gluten fraction played in the pathomechanism of coeliac disease.