title: Effect of cations and temperature on kinetics of desmin assembly.
abstract: Smooth-muscle desmin, which was isolated from avian gizzard, was purified and used to form reconstituted intermediate filaments. Filament assembly was done in the presence of physiological cations, Ca2+, Mg2+, Na+, and Na+ plus Mg2+, and with non-physiological cations Cu2+ and Ni2+. Assembly was done at 2 degrees, 22 degrees and 37 degrees C, and was monitored by absorbance and by electron microscopy. Absorbance increased most rapidly during the first 2-5 min and then increased at a slower rate with the physiological cations, but decreased after that time with the non-physiological cations. For each physiological cation, absorbance increased with increasing temperature. This was particularly evident with Ca2+, which produced the lowest absorbance at 2 degrees C and the highest at 37 degrees C. When ionic strength was comparable, filament-forming buffers that contained bivalent cations were associated with higher absorbance values. Filament diameters were significantly smaller 60 min after assembly initiation than after 5 min. Average filament diameters, when formed in the presence of Cu2+ or Ni2+, were 10% greater than in the presence of the physiological cations and did not show a consistent tendency to decrease as time increased. These results demonstrate the importance, not only of the pH and ionic composition of the filament-forming buffer, but also of the temperature and duration of dialysis for reconstitution of desmin filaments.
authors: Department of Animal Science, Iowa State University, Ames 50011.
authors: M H
authors: MH
authors: Stromer
authors: M A
authors: MA
authors: Ritter
authors: Y Y
authors: YY
authors: Pang
authors: R M
authors: RM
authors: Robson
mesh_terms: D000818:Animals; D002412:Cations / Q000494:pharmacology*; D003893:Desmin; D007700:Kinetics; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D013053:Spectrophotometry; D013696:Temperature
chemical_list: D002412:Cations; D003893:Desmin; D046911:Macromolecular Substances