ELISA Kits for Cell Metabolism Research

1. Cell Metabolic Pathway

1.1 Lipids Metabolism

Lipid metabolism refers to the process of synthesis, decomposition and transformation of lipids such as fatty acids, glycerol, cholesterol and other organic molecules in organisms. Lipid is not only an important source of energy in organisms, but also a key component of cell membrane structure, regulating cell signal transduction and maintaining physiological balance. Lipid metabolism includes fatty acid synthesis, lipid degradation, cholesterol synthesis and other steps. Normal lipid metabolism is essential to maintain health. Still, unbalanced lipid metabolism may lead to health problems such as high cholesterol and hyperlipidemia, and increase the risk of cardiovascular diseases.

1.2 Glycolysis

Glycolysis refers to the metabolic pathway in which glucose is decomposed into pyruvate and ATP in cells. In glycolysis, a six-carbon glucose is decomposed into two three-carbon pyruvic acids by a series of enzyme catalysis, and two ATP molecules (the main storage molecules of energy in cells) and two NADH molecules (coenzyme molecules with energy) are generated at the same time. Under anaerobic conditions, pyruvate can be reduced to lactic acid to maintain the regeneration of NAD+, thus maintaining glycolysis.

Abnormal glycolysis may lead to many diseases, and these abnormalities usually involve defects or mutations of enzymes in glycolytic pathway. Such as glucose-6-phosphatase or phosphofructokinase, which affects energy production and leads to hypoglycemia and other disease symptoms. In addition, in some tumor cells, due to the energy required for rapid proliferation, glycolytic pathway may be over-activated, resulting in a large amount of glucose producing lactic acid through glycolysis, which is called "aerobic glycolysis" or "Warburg effect". This phenomenon has been observed in many cancers such as breast cancer, colon cancer, gastric cancer, prostate cancer, lung cancer and ovarian cancer.

1.3 Protein Metabolism

Protein metabolism refers to a series of biochemical processes responsible for protein and amino acid synthesis (anabolism) and protein decomposition through catabolism. As the most basic molecular machines in life, protein participated in many biological activities, such as cell structure construction, enzyme catalysis, signal transduction, immune response and so on. Protein's anabolism refers to the process of forming protein from amino acids, which mainly includes five steps: amino acid synthesis, transcription, translation, post-translation modification and protein folding. Protein's catabolism refers to the process of breaking down into amino acids or small peptide chains through enzymes (protease, exopeptidase, endopeptidase) or environmental changes. The balance of protein metabolism is very important to maintain the normal function of cells and organisms. Abnormal protein metabolism may lead to many diseases, including liver diseases, kidney diseases, nervous system diseases, muscle diseases and some malignant tumors.

1.4 Nucleotide Metabolism

Nucleotide metabolism includes the process of nucleotide synthesis and degradation, in which there are two ways of nucleotide synthesis: de novo pathway and salvage pathway.

1.4.1 Purine Nucleotide Metabolism:

● Synthetic Metabolism

① De Novo Synthesis: The de novo synthesis pathway of purine nucleotides starts with the synthesis of inosine monophosphate (IMP), which can be converted into adenosine monophosphate (AMP) and guanosine monophosphate (GMP). The process of synthesizing IMP typically involves 10 steps, beginning with the formation of the imidazole ring and then the generation of IMP. The starting point of this synthesis process is phosphoribosyl pyrophosphate (PRPP), which is formed catalytically by 5-phosphoribosyl and ATP under the action of phosphoribosyl pyrophosphate synthetase.

② Salvage Pathway: The salvage pathway of purine nucleotides mainly involves three enzymes: adenosine kinase (ADK), adenine phosphoribosyltransferase (APRT), and hypoxanthine-guanine phosphoribosyltransferase (HGPRT).

● Degradative Metabolism

The end product is uric acid, and excessive uric acid in the body can lead to gout.

1.4.2 Pyrimidine Nucleotide Metabolism

● Synthetic Metabolism

① De Novo Synthesis: De novo synthesis of pyrimidine nucleotides begins with the synthesis of the pyrimidine ring, which then combines with phosphoribosyl pyrophosphate (PRPP) to generate uridine monophosphate (UMP).

② Salvage Pathway: Utilizing free pyrimidine bases or pyrimidine nucleosides within the body as substrates, pyrimidine nucleotides are synthesized through simple reactions involving enzymes like pyrimidine phosphoribosyltransferase or pyrimidine nucleoside kinase.

● Degradative Metabolism

Cytidine monophosphate (CMP) and UMP are first converted to uracil in this pathway, which is eventually transformed into β-alanine. Meanwhile, deoxythymidine monophosphate (dTMP) is first converted to thymidine, which is then transformed into β-aminoisobutyrate salt.

2. Signal Pathways in Cell Metabolism

Signal pathways in cell metabolism are a series of biochemical reactions and molecular interaction networks, which regulate important biological processes such as energy production, material transport, growth and cell fate determination. The following are several common main signal pathways in cell metabolism:

● Ampk (Amp-activated Protein Kinase) Pathway

AMPK is an intracellular energy-sensing protein kinase, which can sense the energy state in cells. AMPK is activated when the ATP level in cells decreases, thus regulating various cellular metabolic pathways, including promoting glucose uptake and oxidation, inhibiting protein synthesis, and promoting autophagy, so as to maintain the energy balance in cells.

● Mtor (Mammalian Target of Rapamycin) Pathway

MTOR pathway is a key cell proliferation and metabolic regulation pathway. MTOR not only senses environmental signals inside and outside cells, but also regulates biological processes such as protein synthesis, cell growth, autophagy and metabolic adaptation. This pathway plays an important role in cell growth, cancer, immunity and metabolic diseases.

● Insulin Pathway

Insulin pathway is a signal transduction pathway regulated by insulin. Insulin activates internal signal pathways through receptors on the cell surface, promoting glucose uptake, protein synthesis and fatty acid synthesis, so as to maintain intracellular sugar metabolism and energy balance.

● PPAR (Peroxisome Proliferator-activated Receptors) Pathway

PPAR is a nuclear receptor, which plays a key role in lipid metabolism and energy balance. When activated, PPAR can regulate fatty acid oxidation, sugar metabolism and insulin sensitivity.

● NRF2 (Nuclear Factor Second-related Factor 2) Pathway

NRF2 is a transcription factor primarily involved in cellular antioxidant stress response. When cells are exposed to oxidative stress or other stressors, NRF2 proteins are released and translocated into the cell nucleus, promoting the expression of antioxidant enzymes and detoxifying enzymes. This process helps alleviate oxidative stress damage. Antioxidant enzymes can clear free radicals and oxidative stress substances within cells, maintaining the balance of oxidation-reduction processes. This balance is crucial for cellular metabolic processes, particularly in the energy production process of the mitochondrial respiratory chain..

These signal pathways are intertwined and jointly regulate the metabolic process in cells. Their normal regulation is very important for maintaining intracellular homeostasis, adapting to environmental changes and preventing metabolic diseases.

3. The Significance of Cell Metabolism Research

The identification of drug targets plays a key role in the discovery and development of safe and effective therapies. In the past, cell metabolism was often thought to only provide "housekeeping" function for organisms, but now it has been proved to have an important contribution to many cell functions. On the other hand, dysfunctional metabolism is also closely related to many different diseases. Therefore, studying the genes, protein and signal pathways that regulate cell metabolism may become a promising way to develop new drugs for metabolic diseases.

4. The List of CUSABIO's Cell Metabolism ELISA Kits