STUDIES ON TRANSCOBALAMIN (TC)|[colon]| QUANTITATAION OF TC II ISOPROTEIN PATTERNS; COMPARISON OF AN ELECTROPHORETIC WITH AN IMMUNOCHEMICAL ASSAY OF TC II IN HUMAN SERUM

摘要

Vitamin B 12 in blood is transported by specific carrier proteins, the transcobalamins (TC I,II and III). TC II is of particular interest since it carries and delivers vitamin B12 to the cells. Polyacrylamid gel electrophoresis was used to separate TC I and III from TC II. Autoradiographic evaluation showed that the TC II fraction is composed of 2, 3 or 4 discrete bands in individual serum samples. This observation and family studies have recently led to the conclusion that these isoprotein patterns present polymorphic variants of TC II. Absolute radioactivity of the gel and relative intensities of the radioactive bands were used to quantitate the TC II fractions.Unsaturated TC II levels were also determined using a new immunochemical method, based on the precipitation of TC II by insolubilised anti-TC II antiserum (radio immunosorbent technique = RIST). The results of TC II determinations with these two basically different assays correlate satisfactorily.