Magnesium equilibration time

Sample powders were dried in a vacuum oven at 60 C for 7 hours and cooled to minimize the hysteresis effect prior to storage in the dessicators of various water activities. In addition to Drierite, five saturated salt solutions were used in dessicators. These salt solutions were lithium chloride, magnesium chloride, potassium carbonate, sodium nitrite and potassium chloride. Their water activities were 0.110, 0.330, 0.440, 0.650 and 0.850, respectively, at 20 C. Each sample contained 1.2 to 1.5 g powder and four-week equilibration time was employed. The percentage of... 

Fig.lA(Left). HPLC (gel filtration) elution profiles of PPDK. The concentration of magnesium included in the incubation mixture and equilibration and elution buffer for the column is shown in each profile. The number above each peak show the elution time. The elution times for PEP carboxylase (Mr. 400,000), catalase (Mr. 240,000) and aldolase(Mr. 158,000) were 12.3 min, 14.9 min and 15.6 min respectively. Fig.lB(Right). Effect of MgCl2 on the quaternary structure of PPDK. 

Fib.2B. HPLC elution profile of PPDK after bringing back the dissociated PPDK to the incubation mixture which contained 10 mM MgCl2 and applying to HPLC column equilibrated with the basic buffer containing 10 mM MgCl2. The elution times for PEP carboxylase and catalase were 16.7 min and 20.1 min, respectively. Note the delay of the proteins in the presence of magnesium 30 in the basic buffer. 

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