Related Experiment Video
Updated: Aug 11, 2026
11:29
HPLC-based Assay to Monitor Extracellular Nucleotide/Nucleoside Metabolism in Human Chronic Lymphocytic Leukemia Cells
Published on: July 20, 2016
A soluble adenosine triphosphate-dependent proteolytic system in human peripheral red blood cells
Blood
|May 1, 1986
Summary
A newly discovered ATP-dependent proteolytic system in young human red blood cells (erythroid cells) degrades abnormal globin chains. This enzymatic activity disappears as cells mature into erythrocytes.
Area of Science:
- Biochemistry
- Cell Biology
- Hematology
Background:
- Human peripheral blood erythroid cells contain a previously undetected adenosine triphosphate (ATP)-dependent proteolytic system.
- This system is particularly active in reticulocytes, which are immature red blood cells.
Purpose of the Study:
- To detect and characterize an ATP-dependent proteolytic system in human erythroid cells.
- To investigate the system's activity in different types of anemia and its substrate specificity.
Main Methods:
- Hemolysates from reticulocyte-rich blood were incubated with a radioactive casein standard in the presence and absence of ATP.
- Proteolytic activity was assessed by measuring the release of trichloroacetic acid (TCA)-soluble peptides.
- The system's properties were compared to a similar system in rabbit reticulocytes.
Main Results:
- Up to 57% of casein was hydrolyzed in the presence of ATP with hemolysates from reticulocyte-rich blood.
- Activity was significantly lower (6-10%) in the absence of ATP or with reticulocyte-poor blood.
- The proteolytic activity was located in the 100,000-g supernatant and inhibited by hemin, N-ethylmaleimide, and sodium vanadate.
- Rabbit reticulocyte lysates with ATP preferentially degraded abnormal human hemoglobins (Leiden and Gun Hill) over hemoglobin A.
Conclusions:
- Human reticulocytes possess an active ATP-dependent proteolytic system capable of degrading abnormal globin chains.
- This enzymatic activity is diminished or lost during the maturation of reticulocytes into erythrocytes.
Related Concept Videos
01:08Hydrolysis of ATP
The bonds of adenosine triphosphate (ATP) can be broken through the addition of water, releasing one or two phosphate groups in an exergonic process called hydrolysis. This reaction liberates the energy in the bonds for use in the cell—for instance, to synthesize proteins from amino acids.
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
01:08Hydrolysis of ATP
The bonds of adenosine triphosphate (ATP) can be broken through the addition of water, releasing one or two phosphate groups in an exergonic process called hydrolysis. This reaction liberates the energy in the bonds for use in the cell—for instance, to synthesize proteins from amino acids.
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
If one phosphate group is removed, a molecule of ADP—adenosine diphosphate—remains, along with inorganic phosphate. ADP can be further hydrolyzed to AMP—adenosine monophosphate—by the removal of a second...
01:42The ADP/ATP Carrier Protein
ADP/ATP carrier or AAC protein is the most abundant carrier protein in the inner mitochondrial membrane. It transports large quantities of ADP and ATP, equivalent to the average human body weight, every day. Among other transporters, ACC protein is one of the best-studied members of the mitochondrial carrier protein family. The ADP/ATP carrier protein comprises two transmembrane helices connected to a loop and a single alpha-helix on the matrix side. It switches between two conformational...
01:31ATP Energy Storage and Release
ATP is a highly unstable molecule. Unless quickly used to perform work, ATP spontaneously dissociates into ADP and inorganic phosphate (Pi), and the free energy released during this process is lost as heat. The energy released by ATP hydrolysis is used to perform work inside the cell and depends on a strategy called energy coupling. Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed.
One example of energy coupling using ATP involves a...
One example of energy coupling using ATP involves a...
01:30ATP Driven Pumps III: V-type Pumps
V-type pumps are ATP-driven pumps found in the vacuolar membranes of plants, yeast, endosomal and lysosomal membranes of animal cells, plasma membranes of a few specialized eukaryotic cells, and some prokaryotes. They are also known as the V1Vo-ATPase, that couple ATP hydrolysis to transport protons against a concentration gradient.
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
The peripheral or cytosolic V1 domain with eight subunits is involved in ATP hydrolysis. The integral or transmembrane V0 domain containing at least five subunits...
01:27Transducer Mechanism: Enzyme-Linked Receptors
Enzyme-linked receptors are cell-surface receptors acting as an enzyme or associating with an enzyme intracellularly. They make excellent drug targets. Drugs can bind to the extracellular ligand-binding domain or directly affect their enzymatic domain and alter their activity.
Major types that are helpful drug targets include:
Major types that are helpful drug targets include: