The catalytic mechanism of tyrosine phenol-lyase from Erwinia herbicola: the effect of substrate structure on pH-dependence of kinetic parameters in the reactions with ring-substituted tyrosines.

Apparently homogeneous tyrosine phenol-lyase (TPL) from Erwinia herbicola has been prepared by a new method. The pH-dependencies of the main kinetic parameters for the reactions of Erwinia TPL with tyrosine, 2-fluorotyrosine, 3-fluorotyrosine, 2-chlorotyrosine, and 3,4-dihydroxyphenylalanine (DOPA) have been studied. The pattern of pH-dependence of V(max) depends on the nature of the substituent in the aromatic ring.

[Comparative study of hazards of energy plutonium and standard Pu-239 using non stochastic effects].

In experiment with rats it was found that the "energy" Pu is more toxic than standard 239Pu when entered endotracheally. The comparison was made by the non-stochastic effects. The toxicity in respiratory system and blood system was 1.

[Modifying effect of tributylphosphate (TBP) and hexachlorbutadien (HCLB) on non-stochastic effects of inhaled Pu-239].

It has been established in experiments on rats that under combined inhalation exposure to 239Pu along with TBP and HCLB in amounts which may cause the changes in blood and immune systems the enhancing of different non-stochastic effects on the average by two times on a basis of a unit absorbed dose in comparison with isolated nuclide inhalation.

[Effect of separate and combined effects of plutonium-239, hexachlorobutadiene and tributyl phosphate on the thymus gland of rats].

It has been established in the experiment on rats exposed to a joint action of plutonium-239, hexachlorobutadiene and ++tributyl phosphate, that manifestations of disturbances from radiation and chemical factors which are more expressed under a joint exposure, are characteristic of the thymus gland damage pattern. As far as lymphocytes count in the organ is concerned, the effect of the joint exposure is no more than additive.