DISCOVERY AND IDENTIFICATION OF FETUIN etuin was discovered in 1944 because of its behavior in
the ultra F 1 centrifuge. In his historical review of fetuin Kai Pedersen the original
discoverer of the protein wrote it (fetuin) was quite different from other serum proteins
previously studied. It precipitated abundantly in an ammonium sulphate concentration range in
which earlier only 7s and 20s components had been observed. Its molecular weight 50 000 was
the lowest observed for a serum protein it was very asym metrical its partial specific volume
was quite low-0. 70 the nitrogen content was low 13g N 100g protein the isoelectric point
was low pH 3. 5. The cause of the low nitrogen value was the high carbohydrate content of
fetuin 23%. The name fetuin (Latin fetus) was proposed because this protein was the
predominating component in the fetal serum rapidly decreased and finally disappeared in the
newborn calf. Proteins with fetuin-like properties were also identified in horse and sheep
fetuses and a small amount of a similar protein was identi fied in human umbilical cord blood
and fetal rabbit blood. ' In the early 1950s with improved fractionation methods many 2 new
proteins were isolated and described. In 1954 Harold Deutsch prepared a new purified fraction
of fetuin that was more uniform than Pedersen' s. During the same period another fetoprotein
a-fetopro 3 fetal blood. Like fetuin this tein (AFP) was first described in human new
component was also an a -globulin.
