The glycosylation as source of the variability in prolactin patterns of individual human amniotic fluids

Whilst it is known that prolactin has size heterogeneity in human amniotic fluid, no studies exist concerning the heterogeneity between individual amniotic fluids and the molecular properties of the prolactin forms which are connected with such a variability. To elecit this, prolactin forms from amniotic fluid taken from 6 full-term deliveries and processed separately, were fractionated by ConA-Sepharose, and characterized by SDS-PAGE, immunoblotting, and glycan detection of blotted prolactins. Recording the absorbance at 280 nm, dimers in the wash of the ConA-Sepharose column and in the elution with methyl-alpha-D-glucoside were evident in 3 fluids. The proteins of the chromatographically more rapid and retarded migrating fractions, generating the first dimer, of unbound material consisted on average of 74-83% and 85-90% of prolactin forms. The eluted fractions (bound material) contained 10-27% of the prolactin amount of the unbound fractions. The electropherograms using 12.5% gels indicated identical patterns of bands in repeated experiments per fluid but variability between the charges. Thus, the apparent molecular masses (kDa) and the proportions to the total prolactin (%) were 14.5-16 (8-12%), 20-23 (3-5%), 24 (4-8%), 25 (6-10%), 27 (19-25%), 28-29 (6-9%), 39-43 (0.5-1.0%), 60-64 (12-19%), 87-90 (8-11%) and 117-140 (2-7%) in nonreducing electrophoretical conditions.(ABSTRACT TRUNCATED AT 250 WORDS)