Summary
Antithrombin III (AT-III) was isolated by heparin affinity chromatography from adult
venous and newborn term and preterm umbilical cord blood. The purified proteins were
compared by SDS-PAGE, rocket immuno-electrophoresis, protein concentration by microbiuret
relative to optical density at 280 nm, heparin cofactor specific activity, progressive
neutralization of thrombin and factor Xa at 37°C and pH related antithrombin kinetics.
The structural evaluations revealed a fetal AT-III of molecular weight, charge and
electrophoretic migration indistinguishable from adult AT-III. The functional studies
showed that, on an equimolar basis, the rates of thrombin and Xa interactions with
fetal AT-III were as rapid as those with adult AT-III. The catalytic rates of various
concentrations of heparin were also equal. The newborn infant, therefore, displays
a quantitative but not qualitative deficiency of AT-III.
Key words
Key words Antithrombin III - Fetal - Adult - Purification - Heparin cofactor activity