Purification and assay of insulin-like growth factor-binding protein-1: measurement of circulating levels throughout pregnancy.
Insulin-like growth factor-binding protein-1 (IGFBP-1) has been purified from amniotic fluid by anion exchange, hydrophobic interaction and gel filtration chromatography. The overall recovery of the purification process was 12.2%. The purified IGFBP-1 yielded a single band on SDS-PAGE gel but showed two bands (34 kDa and 68 kDa) on Western blot under non-reducing conditions. Polyclonal antisera were raised by immunization of sheep using the purified IGFBP-1. The best antiserum bound 50% of 125I-labelled IGFBP-1 at a final dilution of 1:500,000. A radioimmunoassay for IGFBP-1 was developed. This assay had a minimum detection limit of 5 micrograms/l, and was used to determine serum levels in non-pregnant and pregnant women. There was no cross-reaction with a wide variety of materials tested. Serum IGFBP-1 levels in non-pregnant individuals (33 +/- 16 (S.D.) micrograms/l) were found to be significantly lower than those in the second (96 +/- 64 micrograms/l) and third trimesters (95 +/- 60 micrograms/l) of pregnant women. During pregnancy, circulating IGFBP-1 levels increased rapidly in the first trimester and reached a peak at 12-13 weeks of gestation (107 +/- 75 micrograms/l). The level then remained at 80 +/- 53 to 103 +/- 70 micrograms/l until term.
Wang
H S
HS
Department of Reproductive Physiology, St Bartholomew's Hospital Medical College, London.
Perry
L A
LA
Kanisius
J
J
Iles
R K
RK
Holly
J M
JM
Chard
T
T
D000293:Adolescent; D000328:Adult; D000653:Amniotic Fluid / Q000737:chemistry; D002352:Carrier Proteins / Q000097:blood / Q000302:isolation & purification*; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D011247:Pregnancy / Q000097:blood*; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011863:Radioimmunoassay; D013002:Somatomedins / Q000302:isolation & purification* / Q000378:metabolism
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins