Temperature-Induced Protein Conformational Changes in Barley Root Plasma Membrane-Enriched Microsomes: II. Intrinsic Protein Fluorescence

AUTOR(ES)

Caldwell, Charles R.

RESUMO

The membrane-bound proteins of barley (Hordeum vulgare L. cv Conquest) root plasma membrane-enriched microsomes displayed fluorescence typical of protein-associated trytophan residues. The protein fluorescence intensity was sensitive to variations in sample temperature. The temperature-induced decline in protein fluorescence intensity was nonlinear with slope discontinuities at about 12 and 32°C. Detergents at levels above their critical micelle concentration enhanced protein fluorescence. Glutaraldehyde reduced protein fluorescence. Protein fluorescence polarization increased at temperatures above 30°C. Both the rate of tryptophan photoionization and the fluorescence intensity of the photoionization products suggested alterations in membrane protein conformation between 12 and 32°C. The quenching of the intrinsic protein fluorescence by acrylamide and potassium iodide indicated changes in accessibility of the extrinsic agents to the protein tryptophan residues beginning at about 14°C. The results indicate thermally induced changes in the dynamics of the membrane proteins over the temperature range of 12 to 32°C which could account for the complex temperature dependence of the barley root plasma membrane ATPase.

Documentos Relacionados

• Temperature-Induced Protein Conformational Changes in Barley Root Plasma Membrane-Enriched Microsomes: I. Effect of Temperature on Membrane Protein and Lipid Mobility
• Thermal Tolerance of Zymomonas mobilis: Temperature-Induced Changes in Membrane Composition †
• Protein banding patterns of the outer membrane-enriched fraction of Bacteroides bivius.
• Temperature-induced protein synthesis in Bacillus stearothermophilus NUB36.
• Enhanced thermotolerance and temperature-induced changes in protein composition in the hyperthermophilic archaeon ES4.