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Abstract

  1. Top of page
  2. Abstract
  3. REFERENCES

A homogeneous glutamate decarboxylase isolated from pig brain contains 0.8 mol of tightly bound pyridoxal 5-phosphate/enzyme dimer. Upon addition of exogenous pyridoxal 5-phosphate (pyridoxal-5-P), the enzyme acquires maximum catalytic activity.

Preincubation of the enzyme with l-glutamate (10 mM) brings about changes in the absorption spectrum of bound pyridoxal-5-P with the concomitant formation of succinic semialdehyde. However, the rate of this slow secondary reaction, i.e. decarboxylative transamination, is 10−4 times the rate of normal decarboxylation. It is postulated that under physiological conditions enzymatically inactive species of glutamate decarboxylase, generated by the process of decarboxylative transamination, are reconstituted by pyridoxal-5-P produced by the cytosolic enzymes pyridoxal kinase and pyridoxine-5-P oxidase.

The catalytic activity of resolved glutamate decarboxylase is recovered by preincubation with phospho-pyridoxyl-ethanolamine phosphate. The experimental evidence is consistent with the interpretation that the resolved enzyme binds the P-pyridoxyl analog, reduces the stability of the covalent bond of the phospho-pyridoxyl moiety, and catalyzes the formation of pyridoxal-5-P.

Abbreviation
P-Pxy-Etn-P

phospho-pyridoxal-ethanolamine phosphate

Enzymes
 

Glutamate decarboxylase (EC 4.1.1.15)

 

succinic semialdehyde dehydrogenase (EC 1.2.1.24)

 

pyridoxine-5-phosphate oxidase (EC 1.4.3.5)

 

aspartate aminotransferase (EC 2.6.1.1)

 

pyridoxal kinase (EC 2.7.1.35)

REFERENCES

  1. Top of page
  2. Abstract
  3. REFERENCES
  • 1
    Salganicoff, E. & DeRobertis, E. (1965) J. Neurochem. 12, 187202.
  • 2
    McLaughlin, B., Barber, R., Saito, K., Roberts, E. & Wu, J. Y. (1975) J. Comp. Neurol. 164, 305310.
  • 3
    Wu, J. Y., Matsuda, T. & Roberts, E. (1973) J. Biol. Chem. 248, 30293034.
  • 4
    Blindermann, J. M., Maitre, M., Ossola, L. & Mandel, P. (1978) Eur. J. Biochem. 86, 143152.
  • 5
    Spink, D. C., Wu, S. J. & Martin, D. L. (1983) J. Neurochem. 40, 11131119.
  • 6
    Ebadi, M., Wilt, S., Ramaley, R., Swanson, S. & Mebus, C. (1984) Chemical and biological aspects of vitamin B6 catalysis, pp. 255275, Alan R. Liss, New York .
  • 7
    Meeley, M. P. & Martin, D. L. (1983) Cell Mol. Neurobiol. 3, 3954.
  • 8
    Blaner, W. S. & Churchich, J. E. (1979) J. Biol. Chem. 254, 17941798.
  • 9
    Kwok, F. & Churchich, J. E. (1979) J. Biol. Chem. 254, 64896495.
  • 10
    Sizer, J. W. & Jenkins, W. T. (1962) Methods Enzymol. 5, 677684.
  • 11
    Wu, J. Y., Wong, E., Sato, K., Roberts, E. & Schousboe, A. (1976) J. Neurochem. 27, 653659.
  • 12
    Lowry, O. H., Rosebrough, N. J., Farr, A. L. & Randall, R. J. (1951) J. Biol. Chem. 193, 265275.
  • 13
    Severin, E. S., Gulyaev, N. N., Khurs, E. N. & Khomutov, R. M. (1969) Biochem. Biophys. Res. Commun. 35, 318322.
  • 14
    Davis, B. J. (1964) Ann. N. Y. Acad. Sci. 121, 404427.
  • 15
    Levin, O. (1962) Methods Enzymol. 5, 2732.
  • 16
    Wada, H. & Snell, E. E. (1961) J. Biol. Chem. 236, 20892095.
  • 17
    Beeler, T. & Churchich, J. E. (1976) J. Biol. Chem. 251, 52675271.
  • 18
    Sukhareva, B. S. & Braunstein, A. E. (1971) Mol. Biol. 51, 302308.
  • 19
    Tate, S. S. & Meister, A. (1969) Biochemistry 8, 16601668.
  • 20
    Huntley, T. & Metzler, D. (1968) Symposium on pyridoxal enzymes, pp. 8186, Maruzen, Tokyo .
  • 21
    O'Leary, M. H. & Baughn, R. L. (1977) J. Biol. Chem. 252, 71687173.
  • 22
    Churchich, J. E. (1984) Eur. J. Biochem. 138, 327332.
  • 23
    Minelli, A., Borri Voltattorni, C., Grant, P., Basford, J. M. & John, R. A. (1984) Chemical and biological aspects of vitamin B6 catalysis, pp. 289294, Alan R. Liss, New York .
  • 24
    Riva, F., Carotti, D., Barra, D., Giartosio, A. & Turano, C. (1980) J. Biol. Chem. 285, 92309236.
  • 25
    Carotti, D., Riva, F., Santucci, R., Ascoli, F. & Fasella, P. (1982) Eur. J. Biochem. 124, 589593.