Open AccessMalate dehydrogenase and glucose‐6‐phosphate dehydrogenase, key markers for studying the genetic diversity of Actinobacillus actinomycetemcomitans
Author(s) -
Shah Haroun N.,
Andrews David M.A.
Publication year - 1994
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1994.tb07145.x
Subject(s) - malate dehydrogenase , pentose phosphate pathway , phosphogluconate dehydrogenase , dehydrogenase , glucose 6 phosphate dehydrogenase , biochemistry , enzyme , actinobacillus , biology , phosphoglucomutase , hexose , chemistry , glycolysis , bacteria , genetics
Cell‐free extracts of strains belonging to the 5 serotypes of A. actinomycetemcomitans were screened for several enzymes. Enzymes representative of the pentose phosphate pathway/hexose monophosphate shunt and the TCA cycle were present. Of these glucose‐6‐phosphate dehydrogenase (G6PDH) and malate dehydrogenase (MDH) were the most readily detected and stable. MDH and G6PDH retained more than 50% of their activities at alkaline pHs (10–11) for up to 6 h and 3 h at 25°C, respectively, while at pH 6.5, 50% of their activities were lost within 2–3 h. The K m for malate oxidation catalysed by MDH was 5.8×10 −4 M while that for glucose‐6‐phosphate oxidation was 2.0×10 −4 M. The pH optima for MDH and G6PDH oxidation activities were 10 and 9.5, respectively. Among the 5 designated serotypes of A. actinomycetemcomitans three groups were delineated by multilocus enzyme electrophoresis using MDH and G6PDH.