The effects of pressure on sol-gel equilibria, with special reference to myosin and other protoplasmic gels

✍ Scribed by Marsland, Douglas A. ;Brown, Dugald E. S.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1942
• Tongue: English
• Weight: 697 KB
• Volume: 20
• Category: Article
• ISSN: 0095-9898
• DOI: 10.1002/jcp.1030200305

✦ Synopsis

The solatioii of protoplasmic gels by hydrostatic pressure has been demonstrated in many experiments a i d the cellular importance of sol-gel reactions has become increasingly apparent. In the cell, of course, sol-gel reactions must be intimately associated with those metabolic cycles yielding $lie energy for movement. Accordingly, Ebbecke ('36) adopted the view that pressure acts directly, not upon thc gel equilibrium per se, but rather upon the metabolic processes, w-liicli in turn mediate the solatiiig eficct. The weight of evidence, Iiou-e~-ei-, ereii prior to tlic present experiments upon isolated gel systems, iiiclicated that pressure also acts directly upon the substance of the gel, thereby shifting the sol-gel equilibrium. Both actions of pressurc are undoubtedly of great importance, but their identification in intracellular gels is difficult. In order to clarify the situation it was decided to examine the effects of pi4essure upon pure methyl cellulose and myosin gels, thereby permitting a comparison with the data already available on iiitracellular gels.

I n accordance with thermodynamic principles, solation of a gel should result from compression, provided the volume of the gel is greater than that of the corresponding sol. That such gels do exist is clear from the work of Heymaii ( '35). On the basis of this work, Freundlich ( '37) was able to define three types of gels: Type I (e.g., gelatin) displays ' I n the case of myosin gels, the ball was given a thin ront of lxikelite varnish d i i e h pmrtically eliniinnted denaturation of the protein which othrru ise orcnrrcd at the ront:iet surf ace.