Interestingly, the molecular weight of c-PGA was essentially
unchanged regardless of CaCl2 concentration, as indicated by agarose gel electrophoresis (Fig. 1), and by GPC analysis (data not
shown). In contrast to those from studies of Mn2+ or NaCl concentration (Cromwick and Gross, 1995; Shimizu et al., 2007), this finding was possibly because those cations have different effects on the
polymer synthetase system.