Christian de Duve and the Discovery of Lysosomes

In 1949, Belgian cytologist-biochemist Christian de Duve was studying insulin’s effects on liver cells using ultracentrifugation. During his experiments, he observed that when cells were homogenized using an electric blender, they lost most of their enzyme activity when exposed to acid phosphatase.

Further investigation in 1955 led to the discovery of a membrane-bound, sac-like organelle with lytic (tissue-breaking) properties, which he named the lysosome. His findings were later confirmed through electron microscopy in collaboration with Alex Novikoff. This discovery earned de Duve the 1974 Nobel Prize.

Lysosomes: The Cell’s Digestive System

Lysosomes are vital organelles found in all animal cells, especially in white blood cells, which help fight infections. They contain around 50 acid hydrolase enzymes responsible for breaking down proteins, nucleic acids, carbohydrates, and fats.

Their key functions include:

• Digesting foreign materials like viruses and bacteria.
• Removing damaged or excess organelles (cellular housekeeping).
• Recycling nutrients during starvation through autophagy ("self-eating").

Lysosomal Storage Diseases

When lysosomes fail to degrade substances, harmful materials accumulate, leading to cellular malfunctions and organ damage. This results in rare genetic disorders known as lysosomal storage diseases, including:

• Gaucher’s disease
• Tay-Sachs disease

 

In this image of the interior structure of a plant cell, lysosomes are depicted as small orange spheres. Unlike animal cells, plant cells have a cell wall.