Lysosomal enzymes proteoglycan degradation

A deficiency of lysosomal enzymes results in the inability to degrade the carbohydrate portions of proteoglycans or sphingolipids. Partially digested products accumulate in lysosomes. Tissues become engorged with these residual bodies, and their function is impaired. These diseases are often fatal. 

Proteoglycans undergo continuous turnover at rates dependent upon the nature of the proteoglycan and tissue location. Their half-life is between one and several days. Degradation of proteoglycans is initiated by proteolytic enzymes that release glycosaminoglycans the latter are subsequently degraded by lysosomal enzymes. Some of the products of hydrolysis (e.g., dermatan sulfate and heparan sulfate) are excreted in the urine. 

The other lysosomal enzymes listed here, we have demonstrated in liver and kidney lysosomes (6). In conclusion The lactate production and therefore the pH depression in the inflamed synovial system of the gouty joint and also the increased activity of lysosomal proteoglycan degrading enzymes enhance the process of deposition of monosodium urate in joint cartilage. 

Correct answer = C. In mucopolysaccharidoses, synthesis of proteoglycans is unaffected, both in terms of the structure and the amount of material synthesized. The diseases are caused by a deficiency of one of the lysosomal, hydrolytic enzymes responsible for the degradation of glycosaminogly-cans (not the core protein). 

F-1) The mucopolysaccharidoses are proteoglycan disorders that generally result from a hereditary lysosomal defect in enzymes that normally degrade mucopolysaccharides (in most cases heparan sulfate and dermatan sulfate). This leads to the accumulation of different mucopolysaccharides, which may be associated with a variety of different findings, commonly including mental retardation and various skeletal abnormalities. These diseases include Hunter disease, Hurler and Scheie disease, I-cell disease , Maroteaux-Laury disease, Morquio syndrome, Mucolipidoses VH disease, multiple sulfatase deficiency, and Sanfilippo A and B diseases, which will not be elaborated on further here. Often these conditions can be detected in advance on amniocentesis. 

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