THE UNIVERSITY OF MANITOBA STUDIES ON OVINE PLACINTAL ...

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Analytical polyacrylamide gel electrophoresi s -
In acidic polyacryìamide gel e ì ectrophores.i s
(pH a.3-a.5), on'ly one stained band was seen. The presence of opL
was detected in eluants from segments which corresponded to the
stained band. Thus, the data frcm acid. gel suggested ¡¡u¡ the
oPL preparation is homogeneous. In alkaìine polyacrylamide
geì e'lectroph ores i s (pH 9.3-9.5), three stained bands were seen
which were not well separated. The dìstance between each band
being approxlmateìy 0.2-0.3 cm apart. ülhen the geì was d.ivÍdeil
into segments, and when the segments were eìuted and opl actìvity
determined by the RRA-GH, some over'lap in acilvity of the two
darkest bands was apparent. The reason for this observation is not
clear at present. Howeverone possible explanation for thjs
observation may be that aggregation of the hormone occurs in
alkaline buffer. Studies of bGH by Dellacha et al (l968), hpl
by Beìleviìle et al (.1975), bpL by Bolander et al (1976), and
oPL by Hurìey et a] (1977) all have shown aggregation of the
hormones. Hurley et aì (t977) have reported that opl aggregates
reverslb'ly in low ionic strenqth alkal.ine buffer and at high
protein concentrations. The exact amount of contaminat.ing
proteins (the least staîned band) in our opl preparation
is uncertaln, since the intensity of the stained band may not