Hydrolases (also known as hydrolytic enzymes) are a general category of enzymes that have the ability to hydrolyze (decompose by reacting with water) various substrates. These enzymes play key roles in various types of catabolic reactions in cells and play a role in the development of various genetic diseases.
Gangliosides are a class of modified lipids that contain carbohydrates. Gangliosides are a prominent component of neuronal tissue, comprising about 6% of the total lipid content of the brain. Although abundant, the neuronal cells regulate the accumulation of gangliosides in two ways; first by controlling its production and second by breaking down excessive amounts using a specific hydrolase (known as hexosaminidase A). Hexosaminidase A is a lysosomal enzyme that breaks down gangliosides.
In humans, there is an alternative allele for the gene that encodes this hydrolase; homozygous recessive individuals (individuals with two copies of the disease form of the gene) are afflicted with the genetic condition Tay - Sachs disease. The disease is characterized by loss of motor skills beginning between three and six months of age with progressive evidence of neurodegeneration, including seizures, blindness, and eventual death, usually before four years of age. As a result of a founder effect (something we will study later in the course), this disease is most common in people of Ashkenazi Jewish descent.
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