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Direct visualization of phosphorylase-phosphorylase kinase complexes by scanning tunneling and atomic force
R D Edstrom1, M H Meinke, X R Yang
1Department of Biochemistry, Medical School, University of Minnesota, Minneapolis 55455.
Biophysical Journal
|December 1, 1990
Summary
Atomic force microscopy visualized enzyme complexes in skeletal muscle. Phosphorylase kinase changed shape and size upon binding its substrate, phosphorylase b, revealing new insights into muscle activation.
Area of Science:
- Biochemistry
- Molecular Biology
- Muscle Physiology
Background:
- Phosphorylase b activation in skeletal muscle is a critical step in energy metabolism.
- This activation is catalyzed by the enzyme phosphorylase kinase, with both enzymes forming a multienzyme complex in vivo.
Purpose of the Study:
- To visualize and compare enzyme complexes using atomic force microscopy (AFM) and scanning tunneling microscopy (STM).
- To investigate the structural changes in phosphorylase kinase upon binding its substrate, phosphorylase b.
Main Methods:
- Atomic force microscopy (AFM) was employed to image the enzyme complexes.
- Results were compared with previously obtained scanning tunneling microscopy (STM) data.
- Focus was on visualizing the interaction between phosphorylase kinase and phosphorylase b.
Main Results:
- Both AFM and STM were successfully used to view complexes of phosphorylase kinase and phosphorylase b.
- Significant changes in the size and shape of phosphorylase kinase were observed when it bound phosphorylase b.
Conclusions:
- AFM provides a valuable method for imaging enzyme complexes involved in skeletal muscle activation.
- The observed structural alterations in phosphorylase kinase highlight dynamic conformational changes during substrate binding.
- These findings contribute to understanding the regulation of glycogenolysis at a molecular level.