Aug 12, 1976

Steady-state studies of the actin-activated adenosine triphosphatase activity of myosin

Biochimica Et Biophysica Acta
L H Schliselfeld


Reconstituted actomyosin (ATP phosphohydrolase, EC (0.400 mg F-actin/mg myosin) in 10.0 muM ATP loses 96% of its specific ATPase activity when its reaction concentration is decreased from 42.0 mug/ml down to 0.700 mug/ml. The loss of specific activity at the very low enzyme concentrations is prevented by the addition of more F-actin to 17.6 mug/ml. It is concluded that at low actomyosin concentrations the complex dissociates into free myosin with a very low specific ATPase activity and free F-actin with no ATPase. The dissociation of the essential low molecular weight subunits of myosin from the heavy chains at very low actomyosin concentrations may be a contributing factor. Actomyosin has its maximum specific activity at pH 7.8-8.2. The Km for ATP is 9.4 muM, which is at least 20-fold greater than myosin's Km for ATP. The actin-activated ATPase of myosin follows hyperbolic kinetics with varying F-actin concentrations. The Km values for F-actin are 0.110 muM (4.95 mug/ml) at pH 7.4 and 0.241 muM (10.8 mug/ml) at pH 7.8. The actin-activated maximum turnover numbers for myosin are 9.3 s-1 at pH 7.4 and 11.6 s-1 at pH 7.8. The actomyosin ATPase is inhibited by KCl. This KCl inhibition is not competitive with respect to F-...Continue Reading

Mentioned in this Paper

Adenosine Triphosphatases
Actomyosin Location
Chinchilla Rabbits
Filamentous Actin Location
Metabolic Inhibition

About this Paper

Trending Feeds


Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Bone Marrow Neoplasms

Bone Marrow Neoplasms are cancers that occur in the bone marrow. Discover the latest research on Bone Marrow Neoplasms here.

IGA Glomerulonephritis

IgA glomerulonephritis is a chronic form of glomerulonephritis characterized by deposits of predominantly Iimmunoglobin A in the mesangial area. Discover the latest research on IgA glomerulonephritis here.

Cryogenic Electron Microscopy

Cryogenic electron microscopy (Cryo-EM) allows the determination of biological macromolecules and their assemblies at a near-atomic resolution. Here is the latest research.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.

LRRK2 & Immunity During Infection

Mutations in the LRRK2 gene are a risk-factor for developing Parkinson’s disease. However, LRRK2 has been shown to function as a central regulator of vesicular trafficking, infection, immunity, and inflammation. Here is the latest research on the role of this kinase on immunity during infection.

Antiphospholipid Syndrome

Antiphospholipid syndrome or antiphospholipid antibody syndrome (APS or APLS), is an autoimmune, hypercoagulable state caused by the presence of antibodies directed against phospholipids.

Meningococcal Myelitis

Meningococcal myelitis is characterized by inflammation and myelin damage to the meninges and spinal cord. Discover the latest research on meningococcal myelitis here.

Alzheimer's Disease: MS4A

Variants within membrane-spanning 4-domains subfamily A (MS4A) gene cluster have recently been implicated in Alzheimer's disease by recent genome-wide association studies. Here is the latest research.