Effects of Added Denaturant and Helix-forming Agent on Heat-induced Gel Formability of Myosin B and/or Soybean Protein CIF

Abstract

The effects of guanidine hydrochloride(GuHCl)and ethylene chlorohydrine(ECH)on the heat-induced gelation of a mixture of myosin B with soybean protein CIF(cold insoluble fraction), myosin B alone and CIF alone were studied. GuHCl and ECH have generally been used as a denaturant and a α-helix-forming agent, respectively. The results obtained were as follows: In the mixture, the heat-induced gelation decreased gradually with increasing the GuHCl concentration up to 0.6M, then a protein film was formed at 1.2M and the solution turned brown and transparent in appearence at 2.4M. On the other hand, the addition of ECH to the protein solutions accelerated gel formability. Changes of the conformation of the protein molecules after the addition of both agents were discerned from the results of gel filtration. Their greater changes in myosin B and CIF were observed by addition of GuHCl and ECH, respectively. That is, original helical polypeptide chains of myosin B played the key role in the heat-induced gelation. In the solution containing CIF, the heat-induced gelation was promoted in the presence of the helix, and it occurred even in the absence of the helix. In the mixture, the pattern of gel filtration reflected the behavior of CIF and it was suggested that the functional proyerties of soybean protein was prominant.