ISSN:
1432-1017
Keywords:
Eye lens
;
osmotic pressure
;
crystallins concentration gradient
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract A protein concentration gradient exists from the center to the periphery of most lenses, the origin of which is still a matter of debate. The gradient, which contributes to the lens optical quality, seems to be accompanied by an uneven distribution of the crystallin classes, with the nucleus usually enriched in γ-and the cortex in α-crystallins. Since the osmotic pressure within the lens seems to be constant and since a rather different interaction behaviour of α-and γ-crystallins was demonstrated in previous studies, we propose that the maintenance of a constant osmotic pressure through the lens is sufficient to induce and stabilize a protein concentration gradient. The theoretical treatment has been worked out and the validity of the hypothesis has been demonstrated with colloidal osmotic pressure measurements of lens cortical and nuclear cytoplasmic extracts as a function of protein concentration. To account for the observed lens concentration gradient, however, a small additional concentration gradient in the opposite direction, involving an ion or small molecule, might be required.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00257103
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