Particle formation, primary, protein

Nelson, C.D. and Glatz, C.E. (1985) Primary particle formation in protein precipitation. 

The decrease in expansion seems to occur at moisture levels above 30°/o moisture for both cereal (starch-based) polymer systems, and protein (soy grits). This corresponds to a point on their adsorption curves where water activity rises rapidly with added moisture that is, at a level where the water added to a mix has little effect on primary hydration of polymers, but behaves as a diluent. In mechanical terms, this may be explained by proposing that at above levels of 25°/o-30% water plasticisation of the polymers is complete, and further added water acts as a lubricant, reducing the shear-induced temperature rise and particle damage necessary for the formation of homogeneous melts. 

The formation and growth of the primary particle in acid precipitation has been described in terms of the protein supersaturation. Aggregate growth by collision results in a size-dependent rate expression. Aggregate breakage, by shear or collision, remains to be adequately described in light of recent work. 

Because restriction begins soon after infection, both viral RNA and protein synthesis are markedly reduced. The resulting low level of viral macromolecular synthesis delays the inhibition of host functions, impairs virion formation, and prevents physical particle accumulation. Although it is not known which of the three major picornavirus synthetic activities - translation, transcription, or protein processing - is the primary site of restriction, the hypothesis is that at least one of these is impaired. 

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