Browsing by Author "DEIOANNES, A"

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    COMPARATIVE STUDIES ON GLUCOSE PHOSPHORYLATING ISOENZYMES FROM VERTEBRATES .8. IMMUNOCHEMICAL STUDIES ON MAMMALIAN HEXOKINASES-A
    (1985) NUNEZ, L; DEIOANNES, A; URETA, T
    1. An immune serum elicited in a rabbit by injection of homogeneous brain hexokinase A was shown to be specific for the antigen. Other rat hexokinase isoenzymes (kexokinases B, C or D) did not present cross-reaction when tested by immunoinhibition of enyzme activity, double immunodiffusion and immunoadsorbent columns. 2. The enzyme activity of hexokinase A from several mammals (rodents, lagomorphs, artiodactyls) was partially inhibited by the immune serum. In the case of the mouse enzyme, the amount of serum required to inhibit 50% of the activity was five-fold higher than in the case of the rat enzyme. Enzymes from cow or sheep brain were only marginally affected. 3. Hexokinases A isolated from various mammals, tested against the rat enzyme, showed faint lines of precipitation and marked spurs in double immunodiffusion plates even when enzymes from closely related rodents were analyzed. Immunoadsorbent columns, on the other hand, were able to retain most of the activity of hexokinases A from the mammals studied. 4. Micro-complement fixation tests showed that hexokinases A from mammals outside the Order Rodentia were only partially recognized by the anti-hexokinase Arat serum. 5. The results suggest that amino acid substitutions on the hexokinase A molecule have occurred at a rather fast rate.
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    TOXIC EFFECT OF A PHOTOINDUCED TRYPTOPHAN-RIBOFLAVIN ADDUCT ON F9-TERATOCARCINOMA CELLS AND PREIMPLANTATION MOUSE EMBRYOS
    (1988) SILVA, E; SALIMHANNA, M; BECKER, MI; DEIOANNES, A
    Solutions containing L-tryptophan and riboflavin exposed to visible light, under N2 atmosphere, yield a tryptophan-riboflavin adduct, able to inhibit the growth of cultured F9 teratocarcinoma cells. This same effect was found in the presence of a mixture of the tryptophan photooxidation products and the adduct, when using solutions previously irradiated with visible light in an O2 atmosphere. A cytotoxic effect was also observed with embryos incubated in the presence of a tryptophan-riboflavin adduct, in the latter case necrosis and embryo development arrest occured.