THE UNIVERSITY OF MANITOBA STUDIES ON OVINE PLACINTAL ...

f4_
vrith a moLecular weight oÊ 22,OOO (KeIIy et al, Lg74l .
Furthermore r the half-time disappearance rate of rpL from
day 12 and day 19 r"rere also different. rpL from day 12 was
l-9.5 mLnutes whereas from day 19 qras t.2 ¡ninutes.
Xn 1974 Robertson and I'riesen partially purified
rPL from rat placentas. The molecuLar weight of rat placental
J.actogen ís approximately tB,00O as determined by gel filtration
on Sephadex c-lOO, and 221000 M.V¡. as determined by eì.ectro-
phoresÍs upon sodiun dodecyl sulfate (SDS) -polyacrylarnide
gels. The isoelectrÍc point. of rat placentâI lactogen is
between pII 6.5 and 7.0 as determined by isoelectric focusing.
The amino acid composition and primary structure have not
been det,ermined .
!{hen the partially purified rpL bras examined by RRÀ-PRL,
and RRA-GII, ít proved 4lB as active as ovine prolactin standard
(NIH-S-P-1o,25 fV /l¡'r.gl but 169t as active as human placental
lactogen preparation in the RRA-PRL. In the RRA-GH, the
rPL has ninimal gror^rth hormone-like act,ivity.