ABSTRACT
The antigenic structure of glyceraldehyde-3-phosphate dehydrogenase of the most representative Enterobacteriaceae species were compared with an antiserum to Escherichia coli glyceraldehyde-3-phosphate dehydrogenase. The results of the immunodiffusion experiments were confirmed and specified by micro-complement fixation studies. They demonstrated a total immunological identity between the E. coli enzyme and the enzymes of Alcalescens-dispar and the Shigella species, a marked relatedness of the Salmonella species enzyme and a more or less significant relation of the enzymes of the other Enterobacteriaceae species. Moreover, the micro-complement fixation had the same sensitivity and a better selectivity than the DNA/DNA hybridizations. The results show that, like DNA polymerase, this enzyme has evolved more slowly than the other enzymes studied at this time.