Apparent mass anion exchange

Impure monomeric PS I can be further purified on the hydroxyapatite column as shown in Fig. 2 b. The major contaminating component is the cyt.bef-complex, which co-elutes from the anion exchange column. Purified PS I core complex is homogenous and has an apparent molecular mass of about 300 kDa as determined by HPLC gel-filtration (Fig. 3) similar to monomeric PS I isolated from Synechococcus (3). Aggregated PS I particles (Fig. 1), showing an apparent mass of 750 kDa on gel-filtration, may be identical to PS l-trimers (4). 

A number of soil chemical phenomena are characterized by rapid reaction rates that occur on millisecond and microsecond time scales. Batch and flow techniques cannot be used to measure such reaction rates. Moreover, kinetic studies that are conducted using these methods yield apparent rate coefficients and apparent rate laws since mass transfer and transport processes usually predominate. Relaxation methods enable one to measure reaction rates on millisecond and microsecond time scales and 10 determine mechanistic rate laws. In this chapter, theoretical aspects of chemical relaxation are presented. Transient relaxation methods such as temperature-jump, pressure-jump, concentration-jump, and electric field pulse techniques will be discussed and their application to the study of cation and anion adsorption/desorption phenomena, ion-exchange processes, and hydrolysis and complexation reactions will he covered. 

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