A patient with uncontrolled diabetes mellitus experiences persistent hyperglycemia. Over time, this leads to the non-enzymatic attachment of glucose to proteins, particularly hemoglobin (forming HbA1c). This process is known as:
- AGlycosylation
- BAcetylation
- CPhosphorylation
- DUbiquitination
Show answer & explanationAnswer & explanation
Correct answer: A. Glycosylation
The non-enzymatic attachment of sugar molecules (like glucose) to proteins or lipids is known as glycation (often used interchangeably with glycosylation in this context, though technically glycosylation can be enzymatic). This process is a hallmark of chronic hyperglycemia in diabetes and leads to the formation of advanced glycation end products (AGEs), which contribute to diabetic complications. Hemoglobin glycation specifically forms HbA1c.
Why the other options are wrong
- B. Acetylation is the addition of an acetyl group, often to histones or other proteins.
- C. Phosphorylation is the addition of a phosphate group, typically enzymatic.
- D. Ubiquitination is the attachment of ubiquitin, often marking proteins for degradation.
Protein Glycation
Protein glycation is a non-enzymatic reaction where reducing sugars (like glucose) spontaneously attach to proteins. This process is accelerated by high sugar concentrations and can lead to the formation of Advanced Glycation End products (AGEs).
- Non-enzymatic reaction
- Involves reducing sugars (e.g., glucose)
- Forms Schiff bases and Amadori products
- Leads to Advanced Glycation End products (AGEs)
- Relevant to diabetic complications and aging
Memory trick: Sugar GLUEs proteins.