Purification of photochemically active halorhodopsin.

Area of Science:

• Biochemistry
• Molecular Biology
• Photochemistry

Background:

• Halorhodopsin is a light-activated ion pump crucial for cellular function.
• Previous studies lacked methods for purifying halorhodopsin in an active state.

Purpose of the Study:

• To develop a procedure for purifying photochemically active halorhodopsin.
• To characterize the biophysical and photochemical properties of purified halorhodopsin.

Main Methods:

• Membrane solubilization using octyl glucoside.
• Chromatography on hydroxylapatite and octyl-Sepharose gels.
• Spectroscopic analysis and photochemical assays.

Main Results:

• Achieved 270-fold enrichment and 35% yield of purified halorhodopsin.
• Purified halorhodopsin exhibited photochemical activity, including a photocycle and chloride-dependent spectral shifts.
• Apparent molecular weight determined as 25,000 Da.

Conclusions:

• The developed procedure successfully purifies active halorhodopsin.
• Purified halorhodopsin's photochemical properties closely resemble the membrane-bound form.
• This purification method enables further structural and functional studies.