The interaction of ribonuclease A with cupric and zinc ions has been studied spectrophotometrically and by potentiometric titration in the presence and absence of cytidylic acid derivatives. In the absence of cytidylic acid, the results suggest that each cupric ion distributes among a set of approximately four spectrally similar sites; each site appears to consist mainly of a single imidazole s...

The effects of calcium, cupric, ferrous and ferric ions on the formation of trihalomethanes (THMs) and haloacetic acids (HAAs) were investigated using natural organic matter (NOM), small molecular weight NOM surrogates and natural water samples. The results showed that the effects were greatly dependent on the disinfection byproduct (DBP) precursor structure and molecular weight, and metal ions...

The effect of 2’-cytidylic acid and 3’qtidylic acid upon the binding of cupric ions by RNase has been studied by gel filtration, together with the effect of cupric ions upon binding of 2’and 3’-cytidylic acids. The results confirm that binding of 2’-CMP by RNase weakens its athnity for cupric ions; reciprocally, binding of cupric ion diminishes the athnity of RNase for 2’CMP. The negative inter...

Isoflavones are commonly consumed in many Asian countries and have potentially positive effects on human being. Only a few and rather controversial data on their interactions with copper and iron are available to date. 13 structurally related isoflavones were tested in the competitive manner for their Cu/Fe-chelating/reducing properties. Notwithstanding the 5-hydroxy-4-keto chelation site was a...

we studied the effect of different concentrations of alpha-tocopherol on in vitro cupric ions induced oxidation of low density lipoproteins (ldl). human native ldl (50 µg protein/ml) oxidation was induced by 10 µmol/l of cuso4. conjugated dienes were measured spectrophotometrically for up to 440 minutes. the length of the lag phase (tlag), maximum velocity of the reaction (vmax) and the maximum...

The presence of cupric ions or ferric ions was found to enhance the development of color in the indole reaction for the calorimetric determination of deoxyribonucleic acid. The addition of calcium, cobaltous, magnesium, manganous, nickel, or zinc ions did not produce this effect. In the absence of added cupric ions, the indole reaction gave variable results, and the color developed to less than...

Studies of the chemical properties of the enzyme, catecholase, have shown that this polyphenoloxidase consists of a copper-protein complex (l-3). Indications have also been obtained that the enzymic activity of catecholase is associated with the copper part of the molecule, since it has been found that the addition of certain reagents known to react with cupric ions will inhibit the enzymic act...

Carboxamidomethyl derivatives of sperm whale metmyoglobin were prepared by reaction at pH 6.8 with iodoacetamide. The modified protein is similar to previously studied carboxymethyl preparations and shows many of the properties of the native, unmodified protein. Preparations were obtained with compositions in the following ranges, expressed as moles of histidine derivative per mole of protein: ...

We studied the effect of different concentrations of alpha-tocopherol on in vitro cupric ions induced oxidation of low density lipoproteins (LDL). Human native LDL (50 µg protein/ml) oxidation was induced by 10 µmol/L of CuSO4. Conjugated dienes were measured spectrophotometrically for up to 440 minutes. The length of the lag phase (Tlag), maximum velocity of the reaction (Vmax) and the maximum...

Evidence is presented here that cupric ions play a part in the natural spinning of Bombyx mori silk. Proton induced X-ray emission studies revealed that the copper content increased from the posterior part to the anterior part of silk gland, and then further increased in the silk fiber. Spectrophotometric analysis demonstrated that cupric ions formed coordination complexes with silk fibroin cha...