pdf_iconEvaluation of Hen Egg White as a Model of Cytoplasmic Pumping Mechanisms

Cameron, I1,*; Fullerton, G2

1 University of Texas Health Science Center, Department of Cellular and Structural Biology, San Antonio, Texas 78229
2 University of Colorado Denver, Department of Radiology, Aurora, Colorado 80045
* Correspondence: Tel.: (210) 567-3817; E-mail: cameron@uthscsa.edu

Key Words: Hen egg white, albumen structure, gel-sol, proton NMR, polarization microscopy, water

Received 16 May 2010; revised 29 July; accepted 14 August. Published 27 August 2010; available online 27 August 2010

doi: 10.14294/WATER.2010.7



The most widely taught explanation of non-homogeneous distributions of cellu­lar metabolites and ions relies on molecu­lar pumps residing in cellular membranes. This study uses fresh hen egg white to dem­onstrate the capacity of hen egg white to manipulate rheological properties that cor­relate with co-solute distribution changes previously attributed solely to active (en­ergy consuming) membrane pumps. When egg white was placed on a sieve a thin sol albumen fraction flowed through the sieve and a thick gel albumen fraction was ob­tained from the sieve surface. The thick gel, but not the thin albumen sol fraction, ex­cludes a low molecular weight dye, methy­lene blue. The two fractions were examined by polarization microscopy and their wa­ter proton NMR T1 and T2 relaxation times were measured. Thick gel was composed of elongated birefringent domains rich in mi­croscopic particles. The thin albumen sol had no such domains, fewer particles and does not exclude dye. Gel agitation frag­ments the gel domains and frees their par­ticles concomitant with conversion to a sol, and with loss of the dye exclusion property. The gel to sol conversion caused shortening of the NMR T1 relaxation time consistent with increased freedom of motion of water attached to proteins previously entrapped in the less mobile gel. Thus water in the gel differs from bulk water in both motional and dye exclusion properties.

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