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Glutamic acid decarboxylase in Mycobacterium leprae
Archives of Microbiology
|July 1, 1983
Summary
Mycobacterium leprae possesses glutamate decarboxylase, an enzyme that decarboxylates glutamic acid. This inherent metabolic activity may explain the bacterium
Area of Science:
- Microbiology
- Biochemistry
- Enzymology
Background:
- Mycobacterium leprae, the causative agent of leprosy, has an unknown metabolism.
- Glutamic acid is abundant in nerve tissue, suggesting a potential role in M. leprae's neurotropism.
Purpose of the Study:
- To investigate the metabolic capabilities of M. leprae concerning amino acid decarboxylation.
- To determine if M. leprae possesses glutamate decarboxylase activity.
Main Methods:
- Using radiolabeled 1-(14C) glutamic acid to detect decarboxylation by M. leprae suspensions.
- Assessing the reaction's dependence on pyridoxal phosphate and inhibition by hydroxylamine.
- Evaluating the enzyme's characteristics, including temperature sensitivity, substrate inhibition, and pH optimum.
Main Results:
- M. leprae suspensions decarboxylated 1-(14C) glutamic acid to 14CO2.
- The reaction was pyridoxal phosphate-dependent and inhibited by hydroxylamine, confirming it as a true amino acid decarboxylase.
- Enzymatic activity was observed, with optimal function at acidic pH (4.5), indicating microbial origin, and a Km value similar to E. coli.
Conclusions:
- Glutamate decarboxylase (EC 4.1.1.15) is an inherent metabolic activity of M. leprae.
- This enzyme's presence may contribute to M. leprae's neurotropism due to glutamic acid's abundance in nerve tissue.
