Proteins are the engines of the biological world. A diverse set of 20 different amino acids, each with unique features, combine in linear polypeptide polymers to form ‘power houses’ with a wide range of capabilities. Proteins cut and fuse other molecules, act as transport vehicles, transform energy, act as structural building blocks and more. In addition to their significance in the natural world, proteins also have many important industrial applications.

To celebrate Sigma’s great portfolio of protein products, throughout 2017, we will feature 12 protein ‘power-houses’ which showcase the diversity and capabilities of proteins. Search through the wide range of Sigma enzyme and protein products, category indices and online bioinformatics tools on our Enzyme Explorer webpage!

Complete our Online Quiz to learn about these proteins and to win prizes too! You could win a selection of timestrip® indicators and a Lanyard. One lucky winner will also receive an iPad mini by telling us about their favourite protein at the end of the quiz.*

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2017 Archive  

Protein of the Month, October/November: Human chorionic gonadotropin

Human chorionic gonadotropin (hCG) is a hormone produced by the placenta after implantation. The presence of hCG is detected in some pregnancy tests (HCG pregnancy strip tests). Some cancerous tumors produce this hormone; therefore, elevated levels measured when the patient is not pregnant can lead to a cancer diagnosis and, if high enough, paraneoplastic syndromes. However, it is not known whether this production is a contributing cause or an effect of carcinogenesis. The pituitary analog of hCG, known as luteinizing hormone (LH), is produced in the pituitary gland of males and females of all ages.

[Source: Wikipedia]
Did you know?
Human chorionic gonadotropin is glycoprotein composed of 237 amino acids with a molecular mass of 36.7 kDa, approximately 14.5 αhCG and 22.2kDa βhCG.
It is heterodimeric, with an α (alpha) subunit identical to that of luteinizing hormone (LH), follicle-stimulating hormone (FSH), thyroid-stimulating hormone (TSH), and β (beta) subunit that is unique to hCG.
Human chorionic gonadotropin interacts with the LHCG receptor of the ovary and promotes the maintenance of the corpus luteum during the beginning of pregnancy. This allows the corpus luteum to secrete the hormone progesterone during the first trimester. Progesterone enriches the uterus with a thick lining of blood vessels and capillaries so that it can sustain the growing fetus.
Because of its similarity to LH, hCG can also be used clinically to induce ovulation in the ovaries as well as testosterone production in the testes. As the most abundant biological source is women who are presently pregnant, some organizations collect urine from pregnant women to extract hCG for use in fertility treatment.

More product info:
When reconstituted with water to a concentration of 1,000 IU/mL, the vial will also contain 0.1 M sodium phosphate buffer (pH approx. 7.2) and 100 mg/mL of mannitol. hCG is also soluble in aqueous glycerol and glycols, and is insoluble in ethanol. Please, consult the product information sheet for Product C1063 (vial of ~2,500 IU).

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2016 Archive  


Terms and Conditions

One quiz entry per person. Quiz entry valid for customers in Europe, Middle East and Africa only. All quiz entries must be submitted by 31st December 2017.