Description
Introduction: Glycodelin is a glycoprotein belonging to the lipocalin family. There are three putative N-glycosylation sites at Asn-28, Asn-63 and Asn-85, of which the first two are glycosylated. Depending on glycosylation, glycodelin appears in various isoforms. There are three known isoforms of glycodelin, amniotic fluid glycodelin (glycodelin-A, GdA), follicular fluid glycodelin (glycodelin-F, GdF) and seminal plasma glycodelin (glycodelin-S, GdS). The three isoforms have an identical protein backbone but their glycosylation profile is different. In the uterus, glycodelin-A is the major progesterone-regulated glycoprotein secreted into uterine luminal cavity by secretory/decidualized endometrial glands. The other tissues expressing glycodelin include fallopian tubes, ovary, breast, seminal vesicle, bone marrow, and eccrine glands. Glycodelin-A potently and dose-dependently inhibits human sperm-egg binding, whereas differently glycosylated glycodelin-S from seminal plasma has no such effect. In men, glycodelin-S is secreted from seminal vesicle glands to seminal fluid. In women, secretory and decidualised endometrium are the major sites of glycodelin synthesis. Glycodelin is mainly secreted into uterine fluid and amniotic fluid, less to serum. Glycodelin has also been found in many other sites of the body, but not all of them actually synthesise the protein as evidenced by the absence of mRNA. Glycodelin-F is secreted from the granulosa cells into follicular fluid and is taken up by the cumulus cells in which partial deglycosylation takes place to yield glycodelin-C (cumulus cell glycodelin). Glycodelin has significant effects on immune cells, apoptosis, reproduction, cell adhesion, differentiation and cancer. In reproduction, glycodelin contributes to capacitation and immunoprotection of spermatozoa, and it modulates sperm-oocyte binding, acrosome reaction and implantation. In endocrine-related cancer, the differentiation inducing effects of glycodelin are accompanied by growth restriction of malignant cells, decreased expression of oncogenes, increased expression of tumour suppressor genes and morphological reversion of the malignant phenotype.
Principle of the Assay: The microtiter plate provided in this kit has been pre-coated with an antibody specific to glycodelin. Standards or samples are then added to the appropriate microtiter plate wells with a biotin-conjugated antibody preparation specific for glycodelin and Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. Then a TMB (3,3',5,5' tetramethyl-benzidine) substrate solution is added to each well. Only those wells that contain glycodelin, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of a sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450 nm +/- 2 nm. The concentration of glycodelin in the samples is then determined by comparing the O.D. of the samples to the standard curve