Precipitation of Salmon Sperm Deoxyribonucleic Acid with Purine-specific Antibody

Abstract

DEOXYRIBONUCLEIC acids (DNA) have been found to react with antisera prepared by immunizing animals to Gram-negative bacteria¹, DNA², nucleosides^3–5, nucleotides⁴, purines^5–7 and pyrimidines^5,8. This was first demonstrated by complement fixation^1,6 and then by precipitin reaction^3–5. The ease and degree to which these reactions occur seem to depend on the source of the DNA. Pneumo-coccal and E. coli DNA, undenatured and denatured, fix complement with pyrimidine specific antibody; but these and calf thymus DNA are reported to require heat denaturation for complement fixation with anti-purinoyl antibody, although some complement fixation was observed with undenatured pneumococcal and E. coli DNA^6,8. For precipitation, calf thymus DNA required heat denaturation to bring down anti-calf thymus² or anti-uridine antibody³ and heat denaturation in the presence of formaldehyde to precipitate with anti-purinoyl, anti-pyrimidine or anti-nucleoside antibody⁵. In contrast, heat-denatured chick embryo DNA precipitated both with anti-purinoyl and anti-nucleoside antibody⁵. The difference in reactivity between calf thymus and chick embryo DNA was accounted for on the basis of the lack of hyperchromicity for heat-denatured chick embryo DNA and formaldehyde denatured calf thymus DNA, cycled slowly through the thermal transition temperature, compared to a hyperchromicity of 19.5 per cent for heat-denatured calf thymus DNA treated similarly⁵.