Glycoprotein Function as Enzyme

Carbohydrates are ubiquitous in nature, and there is little doubt that the elaborate carbohydrate constructs observed on the surface of cells and proteins hold the key to understanding many complex biological processes. For example, glycoproteins have been reported to exhibit a pivotal role in processes as diverse as fertilization, neuronal development, hormone activities, immune surveillance, and inflammatory responses.

Creative Biolabs offers custom services and technologies for glycoprotein study. Here are some examples of glycoproteins that function as enzymes.

Example One: Alkaline Phosphatases (ALPs)

ALPs are plasma membrane-bound glycoproteins. ALP forms a large family of dimeric enzymes, usually confined to the cell surface hydrolyzes various monophosphate esters at a high pH optimum with the release of inorganic phosphate.

• Physiological Functions of ALP

ALP has been investigated continuously and extensively. But little is known regarding the physiological function of ALPs in most tissues except that the bone isoenzyme has long been thought to have a role in normal skeletal mineralization. A variety of mechanisms have been proposed to explain the role of ALP in bone mineralization. However, apart from its role in normal bone mineralization, the other functions of L/B/K remain obscure both in physiological and neoplastic conditions.

• ALP in Health and Diseases

The activity of liver and bone ALPs in serum has been applied extensively in routine diagnosis. The enzyme ALP is an important serum analyte and its elevation in serum is correlated with the presence of bone, liver, and other diseases. High ALP levels can show that the bile ducts are obstructed. Levels are significantly higher in children and pregnant women. Also, elevated ALP indicates that there could be active bone formation occurring as ALP is a byproduct of osteoblast activity or a disease that affects blood calcium level, vitamin D deficiency, or damaged liver cells. Lowered levels of ALP are less common than elevated levels. Some conditions or diseases may lead to reduced levels of ALP. In addition, the drugs such as oral contraceptives have been demonstrated to reduce ALP.

Several studies have indicated the involvement of ALPs in cellular events such as the regulation of protein phosphorylation, cell growth, apoptosis, and cellular migration during embryonic development. The aberrant expression of ALP genes in cancer has led to the suggestion that ALP isozymes may be involved in tumorigenesis.

Fig.1 A ribbon diagram of L/B/K ALP protein structure. (Sharma, 2014)

Example Two: Patatin Primary Structural Properties and Effects on Lipid Metabolism

Patatin is the trivial name given to a family of glycoproteins that make up >40% of the total soluble protein in potato tubers and serve as a storage protein. Patatin was an O-linked glycoprotein that contained fucose monosaccharides, as well as mannose, rhamnose, glucose, galactose, xylose, and arabinose. Patatin has antioxidant activity and potential anti-cancer effects. Patatin had a fucosylated glycan structural feature, which strongly bound AAL, a known fucose binding lectin. Moreover, the lipid metabolism regulatory effects of patatin on the fat catabolism, fat absorption, and inhibition of lipase activity were measured after high-fat feeding of zebrafish larvae. Results revealed that 37.0 μg/mL patatin promoted 23% lipid decomposition metabolism. Meanwhile, patatin could inhibit lipase activity and fat absorption, whose effects accounted for half that of a positive control drug. The results suggest that patatin, a fucosylated glycoprotein, could potentially be used as a natural active constituent with anti-obesity effects.

Fig.2 (a) A schematic diagram of the oil red O-stained fat analysis area (dotted yellow line). (b) Typical images of fat staining in the intestines and blood vessels. (c) fat signal strength after treatment with different concentrations of patatin. (Wu, 2021)

Custom Services for Glycoprotein With Enzyme Functions

• Glyco-engineered Mammalian Cell Expression System
• Glyco-engineered Pichia pastoris Expression System
• Glyco-engineered Plant-based Expression System
• Therapeutic Glycoprotein Development

Creative Biolabs is a comprehensive and leading biology company. When it comes to researching glycoprotein, you need to partner with a company with a proven track record of success and state-of-the-art technology that can get the job done quickly and efficiently. For these reasons, scientists consistently choose Creative Biolabs as the partner they want to work with. If you are interested in our services or technologies, please contact us for more details.

References

1. Sharma, U.; et al. Alkaline phosphatase: an overview. Indian Journal of Clinical Biochemistry. 2014, 29(3): 269-278.
2. Wu, J.; et al. Patatin primary structural properties and effects on lipid metabolism. Food Chemistry. 2021, 344: 128661.

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