Regulation of skeletal muscle phosphorylase phosphatase activity. I. Kinetic properties of the active and inactive forms

1. 1. The inactivation of phosphorylase a phosphatase decreased the maximum velocity of the phosphorylase a to phosphorylase b conversion reaction when it was assayed at different phosphorylase a concectrations. 2. 2. Maximal phosphorylase a phosphatase activities were found between pH 8 and 8.3. In...

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Bibliographic Details
Authors: Torres, H.N., Chelala, C.A.
Format: article
Status:Published version
Publication Date:1970
Country:Argentina
Institution:Universidad Nacional de Buenos Aires. Facultad de Ciencias Exactas y Naturales
Repository:Biblioteca Digital (UBA-FCEN)
Language:English
OAI Identifier:paperaa:paper_00052744_v198_n3_p495_Torres
Online Access:http://hdl.handle.net/20.500.12110/paper_00052744_v198_n3_p495_Torres
Access Level:Open access
Keyword:adenine nucleotide
caffeine
glucosyltransferase
guanine nucleotide
phosphatase
phosphorus
pyrimidine nucleotide
pyrophosphate
theophylline
animal
article
chemistry
enzyme activation
enzymology
kinetics
muscle
pH
rabbit
Adenine Nucleotides
Animal
Caffeine
Chemistry
Cytosine Nucleotides
Diphosphates
Enzyme Activation
Glucosyltransferases
Guanine Nucleotides
Hydrogen-Ion Concentration
Kinetics
Muscles
Phosphoric Monoester Hydrolases
Phosphorus Isotopes
Rabbits
Theophylline
Uracil Nucleotides
Description
Summary:1. 1. The inactivation of phosphorylase a phosphatase decreased the maximum velocity of the phosphorylase a to phosphorylase b conversion reaction when it was assayed at different phosphorylase a concectrations. 2. 2. Maximal phosphorylase a phosphatase activities were found between pH 8 and 8.3. Inactivation of the phosphorylase a phosphatase led to a decrease in the activity in all the pH ranges tested. 3. 3. Theophylline and caffeine stimulated the phosphorylase a phosphatase. The effect of these substances was exerted in the reaction assay of the enzyme. 4. 4. ATP, ADP, AMP, GTP, UTP, CTP and pyrophosphate were found to decrease the rate of the reaction catalyzed by phosphorylase a phosphatase. This effect showed a striking parallelism with the capacity of these compounds to stimulate the phosphatase inactivation. © 1970.

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