Once the O antigen polymer is connected with the core of lipid A, it will stop the polymerization reaction. That is to say, the connection reaction can terminate the polymerization reaction. Both the core of lipid A and the lipopolysaccharide with different length repeat units can be effectively transferred to the outer membrane. Therefore, the molecular size of lipopolysaccharide can be seen by SDS-PAGE, which is caused by the difference in the biosynthesis system rather than the factor of the output system.

The distribution of the side chain of O antigen in different bacteria is different, some of which contain about 20 repeat units and some of which may be about 100 repeat units. In SDS-PAGE electrophoresis, the difference in silver staining intensity of different molecules of different species of bacteria is reflected. The reason for the different distribution of the side chain length of O antigen in different bacteria may be that there is a size selection factor in the process of O antigen polycondensation or connection reaction. Wzz (i.e. Rol or Cld) is an important protein that regulates the distribution of side chain length in bacteria that synthesize antigens via Wzy dependent pathway, but its specific mechanism is still unclear.