dehydratase and its reactivating factor differ when inside the polyhedral organelles cannot be ruled out.

       If the known subunit composition of diol dehydratase were assumed then

propionaldehyde dehydrogenase would be present in a 2-fold lower amount than the diol dehydratase suggesting that it is a monomer. In addition the enzymes required for cofactor regeneration, adenosyltransferase and the reactivating factor components, would be present at amounts 4-fold lower than diol dehydratase. Together these data suggest that the enzymes associated with the polyhedral organelles are present in amounts sufficient for them to function together.

Unidentified Proteins of the Purified Polyhedral Organelles

     Each protein spot in Figure 4-5 was assigned an identity, with the exception of 19. This protein spot had an apparent pI of 6.8 and an observed molecular mass of 8.6 kDa. These values did not match well with any known pdu protein and protein mass fingerprinting did not match this spot to any protein found in the S. enterica genome. The 37.9 kDa protein corresponding to spot 4 in Figure 4-7 also was analyzed since it was not observed in previous preparations used to identify protein by N-terminal or MALDI-TOF analysis. This may have been due to poor transfer of spot 4 to the membrane used for N-terminal sequencing (Figure 4-4) and poor staining by colloidal blue in the gel used for MALDI-TOF analysis (Figure 4-5). Although the pI of spot 4 was not determined, its position to the right of PduO indicates that it has a pI higher that that of the PduO protein (p1=7.3). Based on this the only possible Pdu protein candidate for the spot 4 is PduX (p1=7.8); however the molecular mass of PduX is 5kDa smaller than that of spot 17 (37.9 kDa). Thus, either PduX runs aberrantly during SDS-PAGE or spot 4 is not encoded by the pdu operon.