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Fluorescence study of N-(3-pyrene)maleimide conjugated to rabbit skeletal F-actin and plasmodium actin polymers
Abstract:
A fluorescent probe N-(3-pyrene)maleimide was conjugated to rabbit skeletal F-actin at the site of most reactive sulfhydryl group (Cys-373). Its fluorescence anisotropy decay showed a single correlation time of 560 ns at 25 degrees C, which is in a very good agreement with the correlation time of the dansyl-L-cysteine group conjugated to the same site of F-actin reported very recently [Wahl, Ph., Mihashi, K, and Auchet, J-C. (1975) FEBS Lett. 8, 164-167]. Actin from plasmodia of myxomycates, Physarum polycepharum, was also conjugated with N-(3-pyrene) maleimide and the fluorescence anisotropy was compared with rabbit skeletal F-actin using the classical steady excitation method. It was found that the internal mobility of the magnesium polymer of plasmodium actin is remarkably larger than both plasmodium F-actin and rabbit skeletal F-actin.
Insights
N-(3-pyrene)maleimide was used to label actin's reactive sulfhydryl group. Plasmodium actin showed greater internal mobility than rabbit skeletal actin, indicating differences in protein dynamics.
Area of Science:
- Biochemistry
- Biophysics
- Cell Biology
Background:
- Actin is a crucial protein in muscle contraction and cell motility.
- Understanding actin's dynamics is key to elucidating its diverse cellular functions.
- Fluorescent probes offer sensitive methods for studying protein structure and dynamics.
Purpose of the Study:
- To investigate the internal mobility of actin from different sources using fluorescence anisotropy.
- To compare the dynamics of rabbit skeletal F-actin with actin from Physarum polycepharum plasmodia.
Main Methods:
- Conjugation of the fluorescent probe N-(3-pyrene)maleimide to the reactive sulfhydryl group (Cys-373) of rabbit skeletal F-actin.
- Measurement of fluorescence anisotropy decay to determine correlation times.
- Comparison of fluorescence anisotropy between rabbit skeletal F-actin and Physarum polycepharum actin.
Main Results:
- The N-(3-pyrene)maleimide probe showed a correlation time of 560 ns at 25°C for rabbit skeletal F-actin.
- This result closely matched previously reported data for dansyl-L-cysteine conjugated to the same site.
- Actin from Physarum polycepharum plasmodia exhibited significantly higher internal mobility compared to both plasmodium F-actin and rabbit skeletal F-actin.
Conclusions:
- The study successfully employed N-(3-pyrene)maleimide as a fluorescent probe for actin dynamics.
- Significant differences in internal mobility exist between mammalian and slime mold actins.
- These findings suggest distinct structural or regulatory mechanisms influencing actin dynamics in different organisms.