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Probing the catalytic site of rabbit muscle glycogen phosphorylase using a series of specifically modified maltohexaose derivatives
- Source :
- Glycoconjugate journal. 34(4)
- Publication Year :
- 2017
-
Abstract
- Glycogen phosphorylase (GP) is an allosteric enzyme whose catalytic site comprises six subsites (SG1, SG−1, SG−2, SG−3, SG−4, and SP) that are complementary to tandem five glucose residues and one inorganic phosphate molecule, respectively. In the catalysis of GP, the nonreducing-end glucose (Glc) of the maltooligosaccharide substrate binds to SG1 and is then phosphorolyzed to yield glucose 1-phosphate. In this study, we probed the catalytic site of rabbit muscle GP using pyridylaminated-maltohexaose (Glcα1–4Glcα1–4Glcα1–4Glcα1–4Glcα1–4GlcPA, where GlcPA = 1-deoxy-1-[(2-pyridyl)amino]-D-glucitol]; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (Glc m -AltNAc-Glc n -GlcPA, where m + n = 4 and AltNAc is 3-acetoamido-3-deoxy-D-altrose). PA-0 served as an efficient substrate for GP, whereas the other PA-0 derivatives were not as good as the PA-0, indicating that substrate recognition by all the SG1 –SG−4 subsites was important for the catalysis of GP. By comparing the initial reaction rate toward the PA-0 derivatives (V derivative) with that toward PA-0 (V PA-0), we found that the value of V derivative/V PA-0 decreased significantly as the level of allosteric activation of GP increased. These results suggest that some conformational changes have taken place in the maltooligosaccharide-binding region of the GP catalytic site during allosteric regulation.
- Subjects :
- 0301 basic medicine
Stereochemistry
Allosteric regulation
Oligosaccharides
Biochemistry
Catalysis
03 medical and health sciences
Glycogen phosphorylase
chemistry.chemical_compound
Allosteric Regulation
Tandem Mass Spectrometry
Catalytic Domain
Glycogen branching enzyme
Animals
Phosphorylase kinase
Molecular Biology
Chromatography, High Pressure Liquid
biology
Glycogen
Chemistry
Muscles
Glycogen Phosphorylase
Substrate (chemistry)
Cell Biology
Adenosine Monophosphate
Kinetics
030104 developmental biology
Allosteric enzyme
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
biology.protein
Rabbits
Subjects
Details
- ISSN :
- 15734986
- Volume :
- 34
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Glycoconjugate journal
- Accession number :
- edsair.doi.dedup.....00d01048da55def962072f429d423e3e