Ultracentrifugal and electrophoretic studies on neonatal calf sera and maternal colostrum

Abstract

1. Neonatal serum proteins and those of maternal colostrum have been examined in the Spinco analytical ultracentrifuge and the Perkin-Elmer electrophoresis apparatus. To facilitate correlations between the two types of result, certain protein fractions have been prepared electrophoretically and examined in the ultracentrifuge.2. The electrophoretically distinguishable components of precolostral serum, albumin, α and β globulin and traces of γ globulin sedimented mainly as a single boundary which showed evidence of a slower component (probably fetuin) with a sedimentation constant of about 3S. A small proportion of a macroglobulin component (S⁰₂₀ ≅ 16S), associated with the α globulin, was also present. In conformity with the very low γ globulin, there was a complete lack of globulin with S⁰₂₀ ≅ 6·5–7·0S. The β globulin and the bulk of the α globulin sedimented closely with albumin, whose sedimentation constant in an electrophoretically isolated fraction was somewhat lower than normal, probably as a result of α-globulin contamination.3. The electrophoretic and ultracentrifuge analysis of postcolostral calf serum showed evidence of passive absorption from the maternal colostrum of immune lactoglobulin. There was a rise in the concentration of total serum protein of which up to 51·6% was immune lactoglobulin, of sedimentation constant 6–6·5S. No such component occurs in precolostral sera. The electrophoretic and ultracen-trifugal characteristics of this globulin were not significantly altered as the result of absorption. The acquisition of immune lactoglobulin was accompanied by a simultaneous fall in serum albumin concentration.4. Examination of colostrum, rennin-produced colostral whey, and of electrophoretic fractions prepared from colostrum showed the presence of a small proportion of a macroglobulin (S⁰₂₀ ≅ 18S), a well-defined immune lactoglobulin of S⁰₂₀ ≅ 6·4S and electrophoretic properties in the γ-range, and a group of electrophoretically more mobile components with sedimentation constants ranging downwards from 3S.5. Electrophoretically prepared fractions from the serum of a deprived calf 27 days old showed sedimentation properties in conformity with the results on precolostral sera, with the macroglobulin component being again associated with α globulin. The remainder of α and β globulin sedimented alongside albumin and the additional γ-globulin component in a single boundary of S⁰₂₀ ≅ 6·5–7S.6. The concentration of autogenous γ globulin developed by calves which had been deprived of colostrum increased with time and was generally in fair agreement with that of the 6·5–7S component.The authors wish to thank Sir Alan Drury, F.R.S., for his interest and encouragement during the course of this work, Mr N. Buttress, Mr D. Hardman and Miss J. Mallon for technical assistance and Mr J. Clark for assistance in the care and handling of the calves.