P. Morini

The response of rat liver lipid peroxidation, antioxidant enzyme activities and glutathione concentration to the thyroid hormone.

1. In liver microsomes from hyperthyroid rats NADPH-dependent lipid peroxidation induces a hydroperoxide formation 56% higher than that in euthyroid ones. 2. The addition of 5 microM Fe2+ (or Fe3+) strongly decreases the hydroperoxide level in favour of that of TBA-reactive substances. Higher iron concentrations (30 microM) have no significant effect. 3. In hepatocytes from hyperthyroid rats CCl4-induced lipid peroxidation produces an amount of TBA-reactive substances four times higher than that in those from euthyroid rats. 4. In the liver of hyperthyroid rats a GSH concentration decrease (by about 35%) is found while the opposite occurs in the blood of the same animals where GSH increases 2.5 times. 5. It is shown that in the liver of hyperthyroid rats, besides higher lipid peroxidation, a more active defense mechanism is operating since both glutathione peroxidase and glutathione reductase specific activities are higher than in euthyroid rats.

Lipid peroxidation in rat liver microsomes. II. Response of hydroperoxide formation to iron concentration.

When rat liver microsomes were incubated with NADPH, the major products were hydroperoxides which increased with time indicating that endogenous iron content is able to promote lipid peroxidation. The addition of either 5 microM Fe2+ or Fe3+ ions strongly enhanced the hydroperoxide formation rate. However, due to the hydroperoxide breakdown, hydroperoxide concentration decreased with time in this case. Higher ferrous or ferric iron concentration did not change the situation much, in that both hydroperoxide breakdown and formation were similar to those when NADPH only was present in the incubation medium. After lipid peroxidation, analysis of fatty acids indicated that the highest amount of peroxidized PUFA occurred in the presence of 5 microM of either Fe2+ or Fe3+. This analysis also showed that after 8 min incubation with low iron concentration, PUFA depletion was about 77% of that observed after 20 min, whereas without any iron addition or in the presence of 30 microM of either Fe3+, PUFA decrease was only about 37% of that observed after 20 min. As far as the optimum Fe2+/Fe3+ ratio required to promote the initiation of microsomal lipid peroxidation in rat liver is concerned, the highest hydroperoxide formation was observed with a ratio ranging from 0.5 to 2. These results indicate that microsomal lipid peroxidation induced by endogenous iron is speeded up by the addition of low concentrations of either Fe2+ or Fe3+ ions, probably because free radicals generated by hydroperoxide breakdown catalyze the propagation process. In experimental conditions unfavourable to hydroperoxide breakdown the principal process is that of the initiation of lipid peroxidation.

Structural and spectroscopic properties of N-benzenesulphonylglycine complexes with copper (II)

In this paper are reported structural and spectroscopic properties of (N-benzenesulphonylglycinato) triaquacopper (II) (complex I) and dipotassium bis (N-benzenesulphonylglycinato) cuprate (II) (complex II). The crystals of (I) are monoclinic, space groupP21/c,Z=4, withα=12.736(4),b=10.292(3),c=10.402(3) Å,β=109.41(2)° while those of complex (II) are orthorhombic, space groupPbca, witha=23.333(8),b=10.508(4),c=16.989(5) Å. In both complexes the aminoacid molecules act as bidentatevia carboxylic oxygen and the amide nitrogen atom; in (I) three water molecules complete the coordination to tetragonal pyramidal, while in (II) coordination is square planar, tetrahedrally distorted involving two ligand molecules. The structure (I) was refined to a finalR index of 0.0596 and (II) toR=0.0466.

Influence of 4-toluenesulphonyl group on the coordination properties of dl-asparagine and l-glutamine

Abstract From the interaction between N-tosyl- dl -asparagine (TsasnH), N-tosyl- l -glutamine (TsglnH) (tosyl = 4-toluenesulphonyl) and copper(II) ion in aqueous solution, compounds of formula CuL 2 ·XH 2 O·YC 2 H 5 OH (L = tosyl-α-aminoacidate monoanion), Cu(LH –1 )·2H 2 O (LH –1 = tosyl-α-aminoacidate dianion) and K 2 [Cu(LH –1 ) 2 ] were isolated. By potentiometric and spectrophotometric measurements, the number and type of complex species and their cumulative formation constants were determined. The treatment of data confirmed, also in solution, the formation of the complexes separated in the solid state and defined the pH range in which they are stable. The coordination behaviour of these ligands is compared with that of parent amino acids and other N-tosyl-derivatives.

Differential action of thyroid hormones on the activity of certain enzymes in rat kidney and brain

In rat kidney several mitochondrial and soluble enzyme activities are stimulated by thyroid hormones and the mitochondrial membrane fluidity is also increased. However, the ketone metabolism enzyme activities of D-3-hydroxybutyrate dehydrogenase and of 3-oxoacid CoA-transferase are not significantly affected by the hyperthyroid state and the ketone body concentration is not greatly changed. Therefore, in hyperthyroid rats the response of the kidney, as far as the ketone bodies and their metabolizing enzymes are concerned, is at variance with that of the liver and the heart. In the brain of young rats, age 8-9 weeks, the activities of the enzymes of ketone body metabolism and those responsible for other metabolic pathways are not influenced by the hyperthyroid state. In these animals, however, the activities of two enzymes, NAD-isocitrate dehydrogenase and pyruvate kinase, are still stimulated by 28 and 41%, respectively. This can be probably related to the higher energy requirement for definitive brain maturation in young hyperthyroid rats.

Magnetic and spectroscopic behavior of amine adducts of copper(II)-N-acetyl-β-alaninate

A series of ternary complexes with the general formula Cu(ac-β-ala)2B2·nH2O (ac-β-ala = N-acetyl-β-alaninate ion;n = 0 and B = ethylenediamine (en), 4-methylpyridine (4pic); n = 2 and B = pyridine (py) and 4pic) and Cu(ac-β-ala)2B(B = piperazine (pipz), 2,2′-bipyridine (bipy), py, 3-methylpyridine (3pic), 4pic) were synthesized and investigated by means of infrared, electronic, e.p.r. spectroscopy and variable temperature magnetic measurements. The green monoamine adducts of py, 3- and 4pic (pKa⩽ 6) showed physical properties which indicated a binuclear geometry as in the parent complex [Cu(ac-β-ala)2·H2O]2·2H2O. The |2J| values of these adducts increased with respect to the hydrate complex, and were comparable to those of carboxylic acids of similar complexity. For this type of complexes the narrow spectral range of v(OCO)as and v(OCO)s indicates only slight dependence on N-protected amino acids. The blue or violet monomeric compounds display spectroscopic properties which indicate a tetragonal configuration whose distortion increases with the basic strength of the amine. For en derivatives all the experimental results are in accord with a square geometry with CuN4 chromophore, the amino acid acting only as a counterion.

Calorimetric and structural investigation of monomeric and dimeric copper(II)-N-protecte daminoacidates

Abstract A calorimetric investigation of the dehydration of structurally-known binary copper(II)- N -protected aminoacidates is reported to compare their relative stability. In order to consider a series of strictly related compounds, the crystal and molecular structure of N -benzoyl-α-alaninate (bz-α-ala) complex is also determined. The compound crystallizes in the triclinic space group P 1 − with 1 formula unit in a cell of dimensions a = 9.425(3), b = 9.579(3), c = 12.644 A, α = 74.10(2)°, β = 78.95(2)°, γ = 88.32(3)°. The structure was solved using the Patterson and Fourier methods and refined by least-squares calculations to a conventional R factor of 5.6% for 3134 counter data. It consists of centrosymmetric tetracarboxylato bridged binuclear molecules showing the copper(II) acetate structure. The calorimetric analysis shows higher dehydration E a values for dimeric species with respect to blue ones which assign a peculiar stability to dimeric structures. The crystal size strongly influences kinetic parameters because the proportion between water molecules on the surface and in the bulk varies with the crystal dimensions.

Amino acids as cations: Tetrachlorocuprates (II) of glycine and β-alanine cations

Abstract The effect of glycine and β-alanine, when act as counterions, on the coordination geometry of the tetrachlorocuprates has been investigated.