Insulin Flashcards
Describe the molecular details of glucose absorption
Digestion: The process of glucose absorption begins with the digestion of carbohydrates in the small intestine. Carbohydrates, such as starch and sucrose, are broken down into simpler sugars, such as glucose, by enzymes such as amylase and sucrase.
Transporter proteins: Once glucose is produced, it needs to be transported across the intestinal epithelium and into the bloodstream. This is accomplished by specialized transporter proteins called sodium-glucose co-transporters (SGLT) and glucose transporters (GLUT). SGLT transporters move glucose across the membrane against its concentration gradient by using the energy from sodium ions, while GLUT transporters move glucose down its concentration gradient.
Absorption: Glucose is absorbed into the enterocytes, the cells that line the small intestine, through the action of the transporter proteins. Once inside the enterocytes, glucose can either be used for energy or transported into the bloodstream for use by other cells in the body.
Insulin: Insulin is a hormone produced by the pancreas that plays a crucial role in glucose absorption. Insulin signals to cells in the body to take up glucose from the bloodstream and use it for energy or store it for later use. Without insulin, glucose cannot enter cells and remains in the bloodstream, leading to high blood sugar levels.
- Describe the formation of advanced glycated end products (AGE)
Advanced Glycation End Products (AGEs) are a group of complex molecules that are formed when sugars react with proteins, lipids, or nucleic acids in a process called glycation. The formation of AGEs occurs naturally in the body as a result of the normal aging process, but can also be accelerated by certain lifestyle factors such as a diet high in sugar and fat, smoking, and oxidative stress.
The process of glycation begins when a sugar molecule (such as glucose) reacts with a protein molecule (such as collagen) or a lipid molecule (such as a fatty acid). This reaction produces a highly reactive intermediate compound known as a Schiff base. The Schiff base then undergoes a series of chemical reactions, ultimately resulting in the formation of an AGE.
AGEs can also be formed by a non-enzymatic process, in which reactive oxygen species (ROS) react with sugars and proteins to form highly reactive intermediates, which then form AGEs through a similar chemical pathway.
The accumulation of AGEs in the body can lead to a number of deleterious effects, including increased oxidative stress, inflammation, and tissue damage. AGEs have been implicated in a wide range of diseases and conditions, including diabetes, cardiovascular disease, Alzheimer’s disease, and cancer.
- Describe the molecular details in the processing of insulin
Synthesis: Insulin is synthesized as a preprohormone in the beta cells of the pancreas. The preprohormone contains a signal peptide that targets the nascent peptide to the endoplasmic reticulum (ER) for processing.
Folding: Once the preprohormone enters the ER, the signal peptide is cleaved, and the proinsulin molecule is formed. Proinsulin consists of three domains: an amino-terminal B-chain, a carboxy-terminal A-chain, and a connecting C-peptide. The proinsulin molecule then undergoes folding, disulfide bond formation, and proper protein folding to create a stable, functional insulin molecule.
Cleavage: Proinsulin is cleaved by specific proteases known as prohormone convertases. The proteases cleave the C-peptide from the insulin molecule, resulting in the formation of insulin and a residual C-peptide fragment. The C-peptide fragment is secreted into the bloodstream along with insulin and can be used as a marker of insulin secretion.
Secretion: The processed insulin is packaged into secretory granules within the beta cells and is released into the bloodstream in response to glucose stimulation. The release of insulin is tightly regulated by a complex feedback system that involves glucose sensing and other signaling pathways.
- Describe the formation of semi-synthetic insulin
Isolation of the insulin gene: The gene that encodes the insulin molecule is identified and isolated from a natural source, typically human or animal pancreas tissue.
Modification of the insulin gene: The insulin gene is modified through site-directed mutagenesis or other genetic engineering techniques to alter specific amino acids within the insulin molecule. These modifications can include changing the amino acid sequence of the B-chain or A-chain, or adding or removing specific amino acid residues to create new insulin analogs.
Expression of the modified insulin gene: The modified insulin gene is introduced into a suitable host cell, such as E. coli or yeast, using recombinant DNA technology. The host cells are then cultured under conditions that allow for expression of the modified insulin gene and production of the desired insulin analog.
Purification and characterization of the insulin analog: The insulin analog is purified from the host cell culture using a variety of chromatographic and other separation techniques. The purified insulin analog is then characterized using a range of analytical methods to ensure that it is structurally and functionally similar to natural insulin.
Describe the synthesis of recombinant insulin and the use of
excipients in the formulations
Recombinant insulin is a type of insulin that is produced by genetic engineering techniques. The process of synthesizing recombinant insulin involves inserting the gene that encodes the insulin protein into a suitable host cell, typically E. coli or yeast. The host cell is then grown in culture, and the insulin protein is expressed and secreted into the culture medium.
The recombinant insulin protein is then purified from the culture medium using a combination of chromatographic and other separation techniques. The purified insulin protein is characterized using a range of analytical methods to ensure that it is structurally and functionally similar to natural insulin.
After purification, the recombinant insulin is typically formulated into a pharmaceutical product for use in the treatment of diabetes. The formulation of recombinant insulin often includes excipients, which are non-active ingredients that are added to the product to improve its stability, solubility, and other physical and chemical properties.
Some common excipients used in the formulation of recombinant insulin include:
Buffering agents: These help to maintain the pH of the insulin product and stabilize the insulin molecule.
Preservatives: These are added to prevent microbial growth and extend the shelf life of the product.
Stabilizers: These help to prevent denaturation and aggregation of the insulin molecule, which can occur during storage and handling.
Surfactants: These are added to improve the solubility and stability of the insulin product.
Tonicity agents: These help to adjust the osmotic pressure of the insulin product to be similar to that of the body.
- Describe the aggregation of insulin and the rationale for the design
of long acting insulin and short acting insulin
Insulin is a protein hormone that plays a key role in regulating glucose metabolism in the body. Insulin exists as a monomer in its active form, but can undergo aggregation under certain conditions, leading to the formation of insoluble aggregates that can impair its activity and bioavailability. Aggregation of insulin can occur due to factors such as pH, temperature, ionic strength, and mechanical agitation.
The aggregation of insulin is a major challenge in the development of insulin products for the treatment of diabetes. Two types of insulin products have been developed to address this challenge: long-acting insulin and short-acting insulin.
Long-acting insulin formulations are designed to provide a steady, sustained release of insulin over an extended period of time, typically 24 hours or more. These formulations are characterized by their ability to form stable, soluble aggregates that slowly dissociate to release insulin into the bloodstream. The key to achieving this sustained release is to modify the insulin molecule in a way that promotes aggregation without impairing its activity.
Short-acting insulin formulations, on the other hand, are designed to rapidly deliver insulin into the bloodstream to control postprandial glucose levels. These formulations are characterized by their ability to rapidly dissociate into monomeric insulin molecules that are rapidly absorbed into the bloodstream. The key to achieving this rapid onset of action is to formulate the insulin molecule in a way that minimizes aggregation and promotes rapid dissociation.
- Describe the mechanism of action of Degludec to supply basal insulin
Degludec is a long-acting insulin analog that is used to provide basal insulin in the treatment of diabetes. The mechanism of action of Degludec involves its ability to form multi-hexamers upon subcutaneous injection, which results in slow and steady release of insulin into the bloodstream.
Degludec has a unique molecular structure that includes a fatty acid side chain, which promotes the formation of multi-hexamers upon subcutaneous injection. These multi-hexamers have a large molecular weight and are slowly absorbed into the bloodstream, resulting in a steady release of insulin over an extended period of time.
Once in the bloodstream, Degludec binds to the insulin receptor on target cells, such as muscle and liver cells. This binding activates a signaling cascade that leads to the uptake and utilization of glucose by these cells. This process helps to maintain normal blood glucose levels throughout the day and night, even during periods of fasting or low food intake.
The long-acting nature of Degludec means that it has a relatively constant effect on blood glucose levels, without the peaks and troughs that are associated with other types of insulin. This provides a more stable and predictable insulin profile, which can help to reduce the risk of hypoglycemia and improve glycemic control over the long term.
