title: A spin labeling study of pig cardiac tropomyosin.
abstract: Tropomyosin (TM) extracted from pig cardiac muscle was spin-labeled with 2,2,6,6-tetramethyl-4-(dichlorotriazin)-aminopiperidine-1-oxyl. The ESR spectra of the product (SL-TM) were of a type of weak immobilization. Effects of three means for the denaturation were observed on the above spectra. The ESR spectrum obtained for SL-TM after enzymatic degradation was found to be analogous to that for the label itself in a dilute solution and thereby the quantity of labels bound in SL-TM estimated. The Arrhenius plots attained through variable temperature measurement for SL-TM's exhibited two inflexion points (the conformational transition temperatures for TM) around 45 degrees C and 74-75 degrees C, the latter temperature having not been reported in literature so far. However, the enzymatic degradation product from SL-TM behaved quite differently from it in the response to microwave power saturation and temperature variation.
authors.affiliation: Shanghai Institute of Biochemistry, Academia Sinica.
authors.forename: H P
authors.initials: HP
authors.lastname: Ye
authors.forename: H L
authors.initials: HL
authors.lastname: Wang
authors.forename: P G
authors.initials: PG
authors.lastname: Sheng
authors.forename: Y S
authors.initials: YS
authors.lastname: Zou
mesh_terms: D000818:Animals; D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D006358:Hot Temperature; D008872:Microwaves; D009206:Myocardium / Q000378:metabolism*; D011487:Protein Conformation; D011489:Protein Denaturation / Q000528:radiation effects; D013113:Spin Labels; D013552:Swine; D014335:Tropomyosin / Q000378:metabolism*
chemical_list: D003497:Cyclic N-Oxides; D013113:Spin Labels; D014335:Tropomyosin; C061303:2,2,6,6-tetramethyl-4-(dichlorotriazin)aminopiperidine-1-oxyl