Centrifuge microfilter

These data seem antithetical most are supportive of a polypeptide or protein, while the centrifuge microfilter data suggest a small peptide. To date we have not been able to prove that there is more than one active substance, e.g., one large and one small. Perhaps a small active substance just happens to share a number of properties with polypeptides and proteins, or perhaps it binds strongly to a larger but inactive polypeptide or protein and masquerades as large. Such a problem has been demonstrated in Culex mosquitoes (56) and been identified as a pitfall in work on Aedes sex peptides. 

The inhibition of LDL oxidation was measured by the method of Esterbauer et al. (40). A 50-pL aliquot of LDL was added to each well in a 96-weU microfilter plate. LDL was preincubated with test compounds at 37 C for 1 h. A 50-p.L aliquot of CuSO solution was added to make a final Cu concentration of 20 pM to induce oxidation. The microfilter plate was again incubated at 37°C for 0.5,1,1.5,2, 2.5,3,3.5,4, or 4.5 h. After incubation, 150 pL of EDTA (2 mM) was added. A 100-pL aliquot from each well was transferred to a minivial. After the addition of 0.9 mL 2-propanol, the mixture was centrifuged. The concentration of conjugated dienes in the supernatant was determined by ultraviolet (UV) absorption at 232 nm. 

Cell-disrupt, centrifuge-by-settling, depth-filter, diafilter, ferment, ferment-continuously, microfilter, sterilize, transfer-through-sterilizer, ultrafilter... 

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