Heinrich Rinderknecht

The use of a nucleopeptide fraction from injected rabbits to study the nature of antigen fragment-RNA association

Abstract A nucleotide peptide ( n − p ) fraction was obtained from liver tissue of ‘normal’, uninjected rabbits and rabbits injected with either 35 S-sulfanilate-azo-BSA or 3 H-aniline-azo-BSA. The n − p of each was fractionated on Sephadex G-50, and since ‘C’ represented a highly-radioactive, UV-absorbing fraction as obtained from the ‘injected’, it was studied further. In a ‘peptide map’ there were 4, UV-absorbing anodic components containing radioactivity, and it was the presence of the latter in the ‘injected’ that distinguished it from the ‘normal’. 3 H and 35 S as labels, in the injected antigen, of a neutral and a negatively-charged group respectively, were present in the same n − p components following high voltage electrophoresis. The latter is strong evidence for covalent linkage between nucleotide and antigen fragment. In addition to three anodic components, an equal number of components having slight cathodic mobility, were biologically-active, substituting at about a 1000-fold less concentration for antigen in ‘triggering’ an anamnestic response in vitro . The present findings are discussed with reference to the role of antigen in protein (antibody) synthesis.

Toxic protein degradation products.

Summary Toxic polypeptides, similar to those obtained by Vaughan(1), have been prepared by treatment of certain proteins with boiling 2% ethanolic sodium hydroxide. These substances are soluble in water and in ethanol, are capable of dialyzing through a cellophane membrane and have been shown to be a mixture of essentially basic polypeptides of similar composition. Their characteristic absorption at 270–280 mμ does not appear to be related to their toxic properties. At an amino acid level the polypeptides differ from their parent proteins in that they contain little or no cystine, serine or threonine. The most toxic preparations, obtained by a salting out procedure, followed by dialysis or by ion exchange chromatography, while nontoxic when given orally were lethal to guinea pigs at a level of 0.5 mg/kg intravenously. Pretreatment of the animals with atropine, epinephrine or Neo-Antergan failed to prevent or modify the effect of a lethal dose of the polypeptide thus excluding liberation of histamine or acetylcholine as the principal cause of toxicity.