Protein Biosynthesis

Question 1

Difference between glycosylated and glycated Hb?

Answer 1

Glycosylated hemoglobin and glycated hemoglobin are related terms often used interchangeably, but they refer to different processes and measurements:

1. Glycosylated Hemoglobin (HbA1c):
   
   • Glycosylated hemoglobin, commonly referred to as HbA1c, is a form of hemoglobin that has glucose molecules attached to it.
   • HbA1c forms when hemoglobin (the protein in red blood cells responsible for carrying oxygen) becomes glycated through a non-enzymatic reaction with glucose in the bloodstream.
   • HbA1c levels provide an indication of average blood glucose levels over a period of approximately 2 to 3 months, reflecting the average glucose concentration to which red blood cells have been exposed during their lifespan (about 120 days).
2. Glycated Hemoglobin:
   
   • Glycated hemoglobin is a broader term that encompasses not only the glycosylation of hemoglobin but also the attachment of sugars to other proteins and macromolecules in the body.
   • While HbA1c specifically refers to glucose attachment to hemoglobin, glycated hemoglobin can refer to the attachment of sugars to any protein in the body, including other types of hemoglobin (such as fetal hemoglobin) or proteins in tissues and organs.
   • Glycated hemoglobin measurements other than HbA1c are less commonly used clinically.

Example:
- Let’s say two individuals, John and Jane, both have diabetes and undergo HbA1c testing to monitor their blood glucose control.
- John’s HbA1c level is measured at 7%, indicating that 7% of his hemoglobin molecules have glucose attached to them, reflecting his average blood glucose levels over the past 2 to 3 months.
- Meanwhile, Jane’s glycated hemoglobin level is also 7%, but in her case, it may refer to the attachment of glucose to other proteins or macromolecules in addition to hemoglobin, providing a broader assessment of glycemic control beyond just HbA1c.

Question 2

What is type of reaction is glycated and glycosylated?

Answer 2

The terms “enzymatic” and “non-enzymatic” refer to the mechanisms by which chemical reactions occur:

1. Enzymatic Reaction:
   
   • An enzymatic reaction involves the participation of enzymes, which are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur.
   • Enzymes are specific to particular substrates (the molecules they act upon) and facilitate the conversion of substrates into products without being consumed themselves.
   • Enzymatic reactions are highly regulated and specific, occurring under specific physiological conditions and often involving complex molecular interactions.
2. Non-Enzymatic Reaction:
   
   • A non-enzymatic reaction occurs without the involvement of enzymes. Instead, chemical reactions proceed spontaneously due to the inherent chemical properties of the reactants.
   • Non-enzymatic reactions typically occur between molecules that react with each other directly, without the need for a catalyst.
   • These reactions may occur at variable rates depending on factors such as temperature, pressure, concentration of reactants, and the presence of catalysts other than enzymes.

In the context of glycosylated and glycated hemoglobin:

• Glycosylated hemoglobin (HbA1c) formation involves a non-enzymatic reaction. Glucose molecules spontaneously attach to hemoglobin proteins circulating in the bloodstream through a chemical process known as glycation. This occurs without the involvement of enzymes.
• In contrast, other biochemical processes in the body, including the breakdown of glucose for energy production, involve enzymatic reactions. Enzymes such as hexokinase, glucose-6-phosphate isomerase, and glucose-6-phosphate dehydrogenase play essential roles in these enzymatic pathways.

Understanding whether a reaction is enzymatic or non-enzymatic helps in deciphering the underlying biochemical mechanisms and designing interventions or treatments targeting those processes.

Question 3

What are prions and virions?

Answer 3

Prions and virions are both infectious agents, but they differ in their composition and mechanism of infection:

Prions:
- Prions are infectious proteins that cause a group of neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs) in animals and humans.
- Unlike viruses, prions do not contain nucleic acids (such as DNA or RNA). Instead, they consist solely of misfolded proteins.
- The normal cellular prion protein (PrP^C) is found in the body, especially in the brain. However, when PrP^C adopts an abnormal conformation (PrP^Sc), it becomes infectious and has the ability to induce other normal PrP^C molecules to misfold into the abnormal form.
- Prion diseases, such as Creutzfeldt-Jakob disease (CJD), mad cow disease (bovine spongiform encephalopathy), and scrapie in sheep, are characterized by the accumulation of misfolded prion proteins in the brain, leading to neuronal damage and progressive neurological dysfunction.

Virions:
- Virions are complete viral particles that consist of genetic material (either DNA or RNA) surrounded by a protein coat called a capsid. Some viruses also have additional structures such as an envelope derived from the host cell membrane.
- Virions are infectious agents that can replicate only inside living cells of organisms (hosts). They infect host cells by attaching to specific cell surface receptors and delivering their genetic material into the host cell.
- Once inside the host cell, the viral genetic material directs the synthesis of viral components and the assembly of new virions, which can then infect other cells.
- Virions cause a wide range of diseases in animals, plants, fungi, bacteria, and other microorganisms, including the common cold, influenza, HIV/AIDS, herpes, and COVID-19.

In summary,

prions are infectious proteins that lack nucleic acids and cause neurodegenerative diseases, while virions are complete viral particles containing genetic material and protein coats that cause a wide variety of infectious diseases in living organisms.