Free radical inactivation of lactate dehydrogenase.

The enzyme lactate dehydrogenase (LDH) has been irradiated under various conditions to assess the relative contributions of -H, -OH, H2O2 and -O2- to LDH inactivation, and it is concluded that -OH is the only important inactivating species. Further the effect of the selective free radicals, -(SCN)2-, -Br2- and -I2- on the activity has been studied. In neutral solution, the order of inactivating effectiveness is -I2- greater than -OH greater than -Br2- greater than -(SCN)2-. At pH 8-6, -OH and -Br2- are approximately equal in effectiveness, whereas -(SCN)2- is the least efficient. The radiation inactivation of LDH is accompanied by a loss of sulphydryl groups, and it is suggested that the primary target for radiation damage in LDH is the active site cysteine-165. Subsequent conformational changes are suggested to account for the apparent loss of coenzyme-binding ability and changes in the enzyme's kinetic parameters. The effect of bound coenzyme (NAD) on radiation-induced inactivation of N2O and air-saturated solutions was also investigated, and it is shown that NAD binding protects LDH.

[1]  M. Eichhorn,et al.  On the radiation-induced aggregates of lactate dehydrogenase. , 1975, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[2]  D. Armstrong,et al.  Formation and repair of papain sulfenic acid. , 1975, Canadian journal of biochemistry.

[3]  Steven J. Steindel,et al.  4 Lactate Dehydrogenase , 1975 .

[4]  M. Tamba,et al.  Primary and secondary radicals in the radiation-induced inactivation of yeast alcoholdehydrogenase. , 1974, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[5]  G. Adams,et al.  Selective free radical reactions with proteins and enzymes: the inactivation of alpha-chymotrypsin. , 1974, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[6]  G. Adams,et al.  Selective free-radical reactions with proteins and enzymes: pulse radiolysis and inactivation studies on papain. , 1974, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[7]  B. Bielski,et al.  Enzyme-catalyzed free radical reactions with nicotinamide-adenine nucleotides: I. Lactate dehydrogenase-catalyzed chain oxidation of bound NADH by superoxide radicals , 1973 .

[8]  C. Gilbert,et al.  Reactions of radiation-induced I-, I2- and I3- with alcohol dehydrogenase and aldolase. , 1973, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[9]  S. Taylor,et al.  Structure-function relationships in lactate dehydrogenase. , 1973, Proceedings of the National Academy of Sciences of the United States of America.

[10]  S. Taylor,et al.  Aminoacid sequence of dogfish M4 lactate dehydrogenase. , 1973, Proceedings of the National Academy of Sciences of the United States of America.

[11]  A. Wiseman,et al.  γ-Radiation Inactivation of Yeast Alcohol Dehydrogenase in the Presence of Oxidized Nicotinamide-Adenine Dinucleotide , 1973 .

[12]  G. Adams,et al.  Selective free radical reactions with proteins and enzymes: the inactivation of ribonuclease. , 1972, Radiation research.

[13]  J. Aldrich,et al.  Selective free radical reactions with proteins and enzymes: reactions of inorganic radical anions with amino acids. , 1972, Radiation research.

[14]  D. Behar,et al.  Pulse radiolysis of aqueous thiocyanate solutions. Nature of the intermediate transient species , 1972 .

[15]  H. Schuessler,et al.  X-ray inactivation of lactate dehydrogenase in dilute solution. , 1972, International journal of radiation biology and related studies in physics, chemistry, and medicine.

[16]  C. Little,et al.  Effects of x-irradiation on the various enzymic functions of NADP plus-linked isocitrate dehydrogenase. , 1971, Canadian journal of biochemistry.

[17]  M. Rossmann,et al.  Structure of Lactate Dehydrogenase at 2.8 Å Resolution , 1970, Nature.

[18]  T. Reece,et al.  Effects of gamma radiation on the chemical and physical properties of lactate dehydrogenase. , 1970, Radiation research.

[19]  C. Little,et al.  Mechanism of peroxide-inactivation of the sulphydryl enzyme glyceraldehyde-3-phosphate dehydrogenase. , 1969, European journal of biochemistry.

[20]  S. Adelstein.  COENZYME BINDING BY X-IRRADIATED GLUTAMATE AND LACTATE DEHYDROGENASE. , 1965, Biochemistry.

[21]  J. Spinks,et al.  Introduction to Radiation Chemistry , 1964 .

[22]  A. Pihl,et al.  X-ray inactivation of papain in solution. , 1963, Radiation research.

[23]  A. Pihl,et al.  Kinetics of enzyme inactivation by ionizing radiation. , 1963, Radiation research.

[24]  S. Adelstein,et al.  The effects of x-irradiation in solution on the kinetic, sedimentation and fluorescent properties of glutamic acid dehydrogenase. , 1961, Biochemical Journal.

[25]  G. Ellman,et al.  Tissue sulfhydryl groups. , 1959, Archives of biochemistry and biophysics.

[26]  A. O. Allen,et al.  Decomposition of Water and Aqueous Solutions under Mixed Fast Neutron and γ-Radiation , 1952 .