Page 1
Lysosome
Institute of Lifelong Learning, University of Delhi
Lesson: Lysosome
Lesson Developer: Rina Majumdar
College/ Department: Botany Department, Maitreyi College,
University of Delhi
Page 2
Lysosome
Institute of Lifelong Learning, University of Delhi
Lesson: Lysosome
Lesson Developer: Rina Majumdar
College/ Department: Botany Department, Maitreyi College,
University of Delhi
Lysosome
Institute of Lifelong Learning, University of Delhi
Table of Contents
Chapter: Lysosome
? Introduction
? Structure
? Role
? Biogenesis
? Lysosomal storage diseases (LSD)
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Page 3
Lysosome
Institute of Lifelong Learning, University of Delhi
Lesson: Lysosome
Lesson Developer: Rina Majumdar
College/ Department: Botany Department, Maitreyi College,
University of Delhi
Lysosome
Institute of Lifelong Learning, University of Delhi
Table of Contents
Chapter: Lysosome
? Introduction
? Structure
? Role
? Biogenesis
? Lysosomal storage diseases (LSD)
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Lysosome
Institute of Lifelong Learning, University of Delhi
Introduction
Nobel Prize laureate Christian de Duve and his co-workers discovered a new microbody in
animal cells in late 1950s, which was named lysosome. Experiments to identify the
localization of the two enzymes glucose-6-phosphatase and acid phosphatase in liver tissue
homogenates by differential centrifugation clearly indicated that acid phosphatase enzyme
was located in a new class of particles never reported before. In addition to acid
phosphatase these new organelles contained several other hydrolytic enzymes including
proteases, lipases,ß-glucoronidases, ribonucleases, deoxyribonucleases all of which have an
apparent role in cellular lysis. C. de Duve named this organelle lysosome for their role in
lysis. The organelle contains approximately 50 different types of hydrolyzing enzymes.
Figure:Under electron microscope, lysosomes are found to be of the size of mitochondrion,
are small electron dense, nearly circular, single membrane structure with the diameter
varies from 0.1-0.8 ?m.
Source:http://www.dematice.org/ressources/PCEM1/Histologie/P1_histo_009/Web/res/figur
e18.jpg
To distinguish lysosome from other small, single membrane electron dense particles within
the cells, in 1952 G.Gomori introduced modified cytochemical procedures and identified the
lysosome based on high acid phosphatase content, which is the marker enzyme for the
organelle.
Page 4
Lysosome
Institute of Lifelong Learning, University of Delhi
Lesson: Lysosome
Lesson Developer: Rina Majumdar
College/ Department: Botany Department, Maitreyi College,
University of Delhi
Lysosome
Institute of Lifelong Learning, University of Delhi
Table of Contents
Chapter: Lysosome
? Introduction
? Structure
? Role
? Biogenesis
? Lysosomal storage diseases (LSD)
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Lysosome
Institute of Lifelong Learning, University of Delhi
Introduction
Nobel Prize laureate Christian de Duve and his co-workers discovered a new microbody in
animal cells in late 1950s, which was named lysosome. Experiments to identify the
localization of the two enzymes glucose-6-phosphatase and acid phosphatase in liver tissue
homogenates by differential centrifugation clearly indicated that acid phosphatase enzyme
was located in a new class of particles never reported before. In addition to acid
phosphatase these new organelles contained several other hydrolytic enzymes including
proteases, lipases,ß-glucoronidases, ribonucleases, deoxyribonucleases all of which have an
apparent role in cellular lysis. C. de Duve named this organelle lysosome for their role in
lysis. The organelle contains approximately 50 different types of hydrolyzing enzymes.
Figure:Under electron microscope, lysosomes are found to be of the size of mitochondrion,
are small electron dense, nearly circular, single membrane structure with the diameter
varies from 0.1-0.8 ?m.
Source:http://www.dematice.org/ressources/PCEM1/Histologie/P1_histo_009/Web/res/figur
e18.jpg
To distinguish lysosome from other small, single membrane electron dense particles within
the cells, in 1952 G.Gomori introduced modified cytochemical procedures and identified the
lysosome based on high acid phosphatase content, which is the marker enzyme for the
organelle.
Lysosome
Institute of Lifelong Learning, University of Delhi
Structure
The lysosomes are bound by a single membrane. The lysosomal membrane separates the
hydrolytic enzymes from the rest of the cell thus protecting the cell from these enzymes.
Highly glycosylated integral proteins present in the lysosome membrane protect the
membrane from the attack by the enclosed enzymes.
The lysosomal enzymes are active at low pH and have a requirement of an acidic pH (4.5 or
less) for their optimal activity. Hence, unlike the cytosolic and most other organelle
enzymes which require a near neutral pH, all the lysosomal enzymes are acidhydrolases.
The internal compartment of the lysosome providesthe low pH.The unique property
of the lysosome membrane, is to maintain its internal acidic pH by actively accumulating H
+
ions (protons) with the help of a V-type proton pump. The high internal proton
concentration is regulated by a proton transporter (H
+
-ATPase) located in the organelles
boundary membrane, which actively transports protons from the cytosol there by
maintaining the near neutral pH of the cytoplasm and a highly acidic pH within the
organelle.
Figure: The lysosome has an acidic pH because of the pumping of protons by a membrane
bound proton pump that imports protons from the cytosol. The enzymes that are present in
the lysosome are active at low pH.
Source: ILLL Inhouse
Table Enzymes present in lysosome
Source: Author
Page 5
Lysosome
Institute of Lifelong Learning, University of Delhi
Lesson: Lysosome
Lesson Developer: Rina Majumdar
College/ Department: Botany Department, Maitreyi College,
University of Delhi
Lysosome
Institute of Lifelong Learning, University of Delhi
Table of Contents
Chapter: Lysosome
? Introduction
? Structure
? Role
? Biogenesis
? Lysosomal storage diseases (LSD)
? Summary
? Exercise/ Practice
? Glossary
? References/ Bibliography/ Further Reading
Lysosome
Institute of Lifelong Learning, University of Delhi
Introduction
Nobel Prize laureate Christian de Duve and his co-workers discovered a new microbody in
animal cells in late 1950s, which was named lysosome. Experiments to identify the
localization of the two enzymes glucose-6-phosphatase and acid phosphatase in liver tissue
homogenates by differential centrifugation clearly indicated that acid phosphatase enzyme
was located in a new class of particles never reported before. In addition to acid
phosphatase these new organelles contained several other hydrolytic enzymes including
proteases, lipases,ß-glucoronidases, ribonucleases, deoxyribonucleases all of which have an
apparent role in cellular lysis. C. de Duve named this organelle lysosome for their role in
lysis. The organelle contains approximately 50 different types of hydrolyzing enzymes.
Figure:Under electron microscope, lysosomes are found to be of the size of mitochondrion,
are small electron dense, nearly circular, single membrane structure with the diameter
varies from 0.1-0.8 ?m.
Source:http://www.dematice.org/ressources/PCEM1/Histologie/P1_histo_009/Web/res/figur
e18.jpg
To distinguish lysosome from other small, single membrane electron dense particles within
the cells, in 1952 G.Gomori introduced modified cytochemical procedures and identified the
lysosome based on high acid phosphatase content, which is the marker enzyme for the
organelle.
Lysosome
Institute of Lifelong Learning, University of Delhi
Structure
The lysosomes are bound by a single membrane. The lysosomal membrane separates the
hydrolytic enzymes from the rest of the cell thus protecting the cell from these enzymes.
Highly glycosylated integral proteins present in the lysosome membrane protect the
membrane from the attack by the enclosed enzymes.
The lysosomal enzymes are active at low pH and have a requirement of an acidic pH (4.5 or
less) for their optimal activity. Hence, unlike the cytosolic and most other organelle
enzymes which require a near neutral pH, all the lysosomal enzymes are acidhydrolases.
The internal compartment of the lysosome providesthe low pH.The unique property
of the lysosome membrane, is to maintain its internal acidic pH by actively accumulating H
+
ions (protons) with the help of a V-type proton pump. The high internal proton
concentration is regulated by a proton transporter (H
+
-ATPase) located in the organelles
boundary membrane, which actively transports protons from the cytosol there by
maintaining the near neutral pH of the cytoplasm and a highly acidic pH within the
organelle.
Figure: The lysosome has an acidic pH because of the pumping of protons by a membrane
bound proton pump that imports protons from the cytosol. The enzymes that are present in
the lysosome are active at low pH.
Source: ILLL Inhouse
Table Enzymes present in lysosome
Source: Author
Lysosome
Institute of Lifelong Learning, University of Delhi
Enzymes Substrate
Proteases and peptidases
? Cathepsin A, B, C, D, E
? Collagenase
? Arylamidase
? Peptidase
Nucleases
? Acid ribonuclease
? Acid deoxyribonuclease
Phosphatases
? Acid phosphatases
? Phosphodiesterase
? Phosphatidic acid phosphatase
Enzymes acting on carbohydrate chains
of glycoproteins and glycolipids
? ßGalactosidase
? Acetylhexosaminidase
? ßGlucosidase
? aGlucosidase
? aMannosidase
? Sialidase
Enzymes acting on glycosaminoglycans
? Lysozymes
Various proteins and peptides
Collagen
Amino acid arylamides
Peptides
RNA
DNA
Phosphate monoesters
Oligonucleotides, Phosphodiesters
Phosphatidic acids
ßGalactosides
Acetylhexosaminides, heparin sulfate
ßGalactosides
Glycogen
aMannosides
Sialic acid derivatives
Mucopolysaccharides, bacterial cell wall
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