This can also be detected in plasma, serum and urine samples. A nicked or cleaved hCG is produced. Nicked hCG is most evident in serum and urine samples in the later trimesters of pregnancy. It may be the principal form of hCG detected in choriocarcinoma patients, and in germ cell and other cancer cases. Nicking occurs by the action of proteolytic enzymes in the placental, mole or cancer tissue, or in the circulation.
White ribbon indicates alpha-subunit peptide.
Nicked free -subunit is rapidly removed from the circulation. While the molecular weight of hCG is 36,700, the molecular weight of -core fragment is only 10,000. Green E,D., and Baenziger, J.U. Asparagine-linked oligosaccharides on lutropin, follitropin, and thyrotropin. Distributions of sulfated and sialylated oligosaccharides on bovine, ovine, and human pituitary glycoprotein hormones. Blithe D.L., and Nisula B.C. Variations in the oligosaccharides on free and combined alpha -subunit of human choriogonadotropin in pregnancy.