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Published on: December 18, 2013
Conformation and stability of elastase from Atlantic cod, Gadus morhua
G Jayaraman1, S Srimathi, J B Bjarnason
1Centre for Protein Engineering and Biomedical Research, The Voluntary Health Services, Adyar, Chennai 600 113, India. raman291068@yahoo.com
Biochimica Et Biophysica Acta
|October 11, 2005
Summary
Atlantic cod elastase (ACE) stability is enhanced by calcium ions, while other metals inhibit activity. This psychrophilic enzyme exhibits remarkable stability, with low unfolding energy suggesting adaptation to cold environments.
Area of Science:
- Biochemistry
- Enzymology
- Protein Chemistry
Background:
- Psychrophilic enzymes, like Atlantic cod elastase (ACE), possess unique stability characteristics crucial for function in cold environments.
- Understanding the metal-binding and conformational stability of ACE provides insights into enzyme adaptation and function at low temperatures.
Purpose of the Study:
- To investigate the metal-binding properties and conformational stability of psychrophilic elastase (ACE) from Atlantic cod (Gadus morhua).
- To determine the effects of pH, metal ions, and denaturants on ACE activity and structure.
- To compare the stability of ACE with mesophilic elastases and propose a mechanism for its cold adaptation.
Main Methods:
- Enzyme activity assays were performed in the presence of various metal ions and EDTA.
- Conformational stability was monitored by changes in tryptophan fluorescence during pH and guanidinium chloride-induced denaturation.
- Thermal denaturation (Tm) and guanidinium chloride-induced denaturation (Cm, ΔG(H2O)) were analyzed at different pH values.
Main Results:
- Calcium (Ca2+) chelation is vital for ACE's active conformation and thermal stability; other metal ions (Zn2+, Fe3+, Cu2+) and EDTA inhibit its hydrolytic activity.
- ACE exhibits a two-state unfolding pattern across a wide pH range, with transition midpoints at pH 4.08 and 10.29.
- The enzyme displays exceptionally low unfolding energy (ΔG(H2O) = 6.91 kJ mol−1 at pH 8.0), the lowest reported for psychrophilic enzymes, indicating high stability. Acidic conditions (pH 5.50) slightly decrease unfolding energy but increase thermal stability (Tm).
Conclusions:
- ACE's stability is significantly influenced by Ca2+ binding, crucial for its biological activity and thermal resilience.
- The enzyme's low unfolding energy and distinct denaturation patterns highlight its adaptation to psychrophilic conditions.
- Proposed mechanisms for cold adaptation involve potential intermolecular associations at acidic pH and elevated temperatures, contributing to enhanced stability.
