Macromolecular crowding

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Most importantly, reaction rates in nanofluidic systems can be controlled both by shape and volume changes. The important interplay between chemical reactions and geometry has been conceptualized within a theoretical framework for ultra-small volumes and tested on a number of experimental systems, opening pathways to more complex, dynamically compartmentalized ultra-small volume reactors, or artificial model cells, that offer more detailed understanding of cellular kinetics and biophysical phenomena, such as macromolecular crowding. 

As weU as age-related reductions in cell volume, there may also be contributions to macromolecular crowding from age-related decline in proteasomal activity. Decreases in protein degradation would result in increases in the concentration of all cytoplasmic proteins. It has been found that inhibition of proteasomal activity leads to the formation of a-synuclein inclusions without, however, significantly increasing the concentration of a-synuclein. Reduced protease activity has been measured in Parkinson s disease brains. Also protease activity in PC12 cells is known to be reduced by over-expression of a-synuclein. 

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