[Immunochemical comparison of tryptophanyl-tRNA-synthetases]

A fraction of immunoglobulins was isolated from the sera of rabbit immunised by a homogeneous beef pancreas tryptophanyl-tRNA-synthetase (TRSase). The IgG fraction was shown to inhibit the enzymatic activity during aminoacylation of yeast tRNATrp and tryptophan activation. By using the radioimmunoadsorption technique, the interaction of IgG was tested with TRSaes from beef pancreas and identical enzymes from other sources (contained in the total preparation). Beef liver TRSase efficiently inhibited the radioimmunoadsorption reaction of beef pancrease 125J-TRSase that suggests a strong similarity or even identity of the enzymes. When the purified antibodies to beef pancreas TRSase were isolated common antigen determinants were revealed for TRSase from beef pancreas, liver of chick, pig and rat. Enzymatic activity of TRSase from liver of beef, pig and chick was shown to be inhibited by antibodies to beef pancreas. TRSase whereas the enzymes from rat liver and yeast did not change their activity in the presence of these antibodies. Therefore, for several TRAases common antigen determinants have been revealed that suggest the presence of common structural elements in these enzymes; antibody binding inhibits the activity of some TRSases and does not affect that of others.