Antigenic reactivities of fragments obtained by cyanogen bromide cleavage of bovine .ALPHA.s1-casein toward antiserum to intact .ALPHA.s1-casein.

Abstract

To study the preliminary localization of the antigenic sites of bovine αs1-casein, we separated fragments 1 ~ 54, 55 ~ 60, 61 ~ 123, 124 ~ 135, 136 — 196 and 197 ~ 199 from αs1-casein cleaved with cyanogen bromide, and examined the antigenic reactivities of the fragments with antiserum to intact αs1-casein.On quantitative precipitation between αs1-casein and its antiserum, a mixture of fragments 1 ~ 54, 55 ~ 60, 61 ~ 123, 124 ~ 135, 136 ~ 196 and 197 ~ 199 inhibited the formation of immune precipitates by 84.2%. Four of these six fragments, i.e. fragments 1 ~ 54, 61 — 123, 124 ~ 135 and 136 ~ 196, still showed high antibody-binding activities in the quantitative immunoprecipitin inhibition test and an enzyme-linked immunosorbent assay. Furthermore, on immunodiffusion analysis, only fragment 61 ~ 123 formed a single and sharp precipitin arc.These results indicate that at least one antigenic site of αs1-casein is associated with each of regions 1 ~ 54, 124 ~ 135 and 136 — 196, and more than two with region ...