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Zn2+ binding to cardiac calsequestrin
Biochemical and Biophysical Research Communications
|April 6, 1995
Summary
Cardiac calsequestrin binds significant amounts of zinc (Zn2+), potentially modulating its structure and function. This study confirms calsequestrin as a dual calcium and zinc-binding protein.
Area of Science:
- Biochemistry
- Molecular Biology
- Cardiology
Background:
- Cardiac calsequestrin is crucial for calcium (Ca2+) handling in heart muscle.
- The role of other divalent cations, like zinc (Zn2+), in calsequestrin function is less understood.
Purpose of the Study:
- To investigate the binding of zinc (Zn2+) to canine cardiac calsequestrin.
- To determine the affinity and characteristics of Zn2+ interaction with calsequestrin.
Main Methods:
- Utilized Zn2+-specific fluorescence dye salicylcarbohydrazone (SACH).
- Employed 65Zn2+ overlay assays and Zn(2+)-IDA chromatography.
- Analyzed protein conformation using circular dichroism.
Main Results:
- Cardiac calsequestrin binds approximately 200 moles of Zn2+ per mole of protein (Kd = 300 microM).
- Zn2+ binding induced protein aggregation but did not involve histidine residues.
- Observed only minor Zn2+-dependent conformational changes via circular dichroism.
Conclusions:
- Cardiac calsequestrin is a Ca2+- and Zn2+-binding protein.
- Zn2+ binding may influence calsequestrin's structure and function in cardiac muscle.