Proteoglycans contain up to what percentage carbohydrate by weight?

Proteoglycans are large macromolecules that play essential roles in the extracellular matrix (ECM) and are composed of a core protein covalently attached to glycosaminoglycan (GAG) chains. The carbohydrate content in proteoglycans is significantly high compared to other proteins, primarily due to the presence of these GAGs.

The high carbohydrate content can be attributed to the structure of GAGs, which are long, unbranched polysaccharides that are typically negatively charged and often attract water, contributing to the hydrophilic nature of the ECM. In fact, proteoglycans can contain up to 80% carbohydrate by weight, with the carbohydrate component being largely due to the multiple GAG chains attached to the core protein.

Therefore, the choice indicating that proteoglycans contain up to 60% carbohydrate by weight aligns with the general understanding of their composition, but it significantly underestimates the typical range. The overarching principle is that the carbohydrate proportion is indeed substantial, making the choice indicating 80% acknowledge the true biochemical significance of proteoglycans in the ECM.