Correlation between biochemical features and pathogenicity of Shigella. IV. Threonine deaminase of Shigella strains producing and not producing keratoconjunctivitis in guinea pigs
Stypulkowska-Misiurewicz, H.; Noworyta, J.
Medycyna Doswiadczalna i Mikrobiologia 28(2): 131-136
1976
ISSN/ISBN: 0025-8601 PMID: 775224 Document Number: 97596
An attempt was made to determine differences in threonine metabolism between model strain S. flexneri 2a and its variant avirulent in guinea pig keratoconjunctivitis test. Extracts of the virulent strain showed a threonine deaminase activity 71.8% higher than those of the avirulent variant. The enzyme of the virulent strain had higher affinity to L-threonine (Km = 29.2 .mu.M) than that of the avirulent variant (Km = 24.2 .mu.M), and there was no feedback inhibition of its activity by isoleucine. The 2 variants, differing in virulence, may also differ in the enzyme apparatus involved in N metabolism, including enzymes that exert threonine deaminase activity.