Oxovanadium ions bind transfer RNA at multiple sites.

Oxovanadium compounds exert preventive effects against chemical carcinogenesis in animals and form complexes with DNA and RNA in vivo. This study was designed to examine the interaction of transfer RNA (tRNA) with VO(2+) and VO₃⁻ ions in aqueous solution at physiological pH, with constant a tRNA concentration of 12.5 mM and different vanadium/RNA (P) (P = phosphate) molar ratios (r) of 1:60 to 1:2.

DNase I - DNA interaction alters DNA and protein conformations.

Human DNase I is an endonuclease that catalyzes the hydrolysis of double-stranded DNA predominantly by a single-stranded nicking mechanism under physiological conditions in the presence of divalent Mg and Ca cations. It binds to the minor groove and the backbone phosphate group and has no contact with the major groove of the right-handed DNA duplex. The aim of this study was to examine the effects of DNase I - DNA complexation on DNA and protein conformations.

Conformational analysis of Na,K-ATPase in drug-protein complexes.

This review reports the effects of several drugs such as AZT (anti-AIDS), cis-Pt (antitumor), aspirin (anti-inflammatory) and vitamin C (antioxidant) on the stability and conformation of Na,K-ATPase in vitro. Drug-enzyme binding was found to be via H-bonding to the polypeptide CO and C-N groups with two binding constants K(1(AZT))=5.30 (+/-2.

Protein unfolding in drug-RNase complexes.

Bovine pancreatic ribonuclease A (RNase A) catalyzes the cleavage of P-O5' bonds in RNA on the 3' side of pyrimidine to form cyclic 2', 5'-phosphates. It has several high affinity binding sites that make it possible target for many organic and inorganic molecules. Ligand binding to RNase A can alter protein secondary structure and its catalytic activity.

An overview of DNA and RNA bindings to antioxidant flavonoids.

In this report we are examining how the antioxidant flavonoids can prevent DNA damage and what mechanism of action is involved in the process. Flavonoids are strong antioxidants that prevent DNA damage. The anticancer and antiviral activities of these natural products are implicated in their mechanism of actions.

The effects of drug complexation on the stability and conformation of human serum albumin: protein unfolding.

We report different analytical methods used to study the effects of 3\'-azido-3\'-deoxythymidine, aspirin, taxol, cisplatin, atrazine, 2,4-dichlorophenoxyacetic, biogenic polyamines, chlorophyll, chlorophyllin, poly(ethylene glycol), vanadyl cation, vanadate anion, cobalt-hexamine cation, and As2O3, on the stability and secondary structure of human serum albumin (HSA) in aqueous solution, using capillary electrophoresis, Fourier transform infrared, ultraviolet visible, and circular dichroism (CD) spectroscopic methods. The concentrations of HSA used were 4% to 2% or 0.6 to 0.

DNA interaction with naturally occurring antioxidant flavonoids quercetin, kaempferol, and delphinidin.

Flavonoids are strong antioxidants that prevent DNA damage. The anticancer and antiviral activities of these natural products are implicated in their mechanism of actions. However, there has been no information on the interactions of these antioxidants with individual DNA at molecular level.

Taxol anticancer activity and DNA binding.

The interaction of taxol with DNA has major biological importance since it is shown the presence of higher concentration of taxol in the nucleus, than in the human lung tumor cell. Therefore, in this report we examine the interaction of taxol with calf-thymus DNA in aqueous solution at physiological pH, using constant DNA concentration (25 or 1.25 mM phosphate) and various taxol/DNA (phosphate) ratios 1/200 to 1/2.

DNA adducts with chlorophyll and chlorophyllin as antimutagenic agents: synthesis, stability, and structural features.

Porphyrins and their metal derivatives are strong DNA binders with association constants of 10(5) M(-1) to 10(7) M(-1). Some of these compounds have been used for radiation sensitization therapy of cancer and are targeted to interact with cellular DNA. Chlorophyll (CHL) and chlorophyllin (CHLN), a food-grade derivative of chlorophyll, the ubiquitous green plant pigment widely consumed by humans, are potent inhibitors of experimental carcinogenesis.

Effects of organic and inorganic polyamine cations on the structure of human serum albumin.

The presence of several high affinity binding sites on human serum albumin (HSA) makes it a possible target for many organic and inorganic molecules. Organic polyamines are widely distributed in living cells and their biological roles have been associated with their physical and chemical interactions with proteins, nucleic acids, and lipids. This study is designed to examine the effects of spermine, spermidine, putrescine, and cobalt [Co(III)]-hexamine cations on the solution structure of HSA using Fourier transform IR, UV-visible, and circular dichroism (CD) spectroscopic methods.

3'-azido-3'-deoxythymidine binding to ribonuclease A: model for drug-protein interaction.

Ribonuclease A (RNase A) with several high affinity binding sites is a possible target for many organic and inorganic molecules. 3'-Azido-3'-deoxythymidine (AZT) is the first clinically effective drug for the treatment of human immunodeficiency virus (HIV) infection. The drug interactions with protein and nucleic acids are associated with its mechanism of action in vivo.

Secondary structural analysis of the Na(+),K(+)-ATPase and its Na(+) (E(1)) and K(+) (E(2)) complexes by FTIR spectroscopy.

The Na(+),K(+)-ATPase is an integral membrane protein which transports sodium and potassium cations against an electrochemical gradient. The transport of Na(+) and K(+) ions is presumably connected to an oscillation of the enzyme between the two conformational states, the E(1) (Na(+)) and the E(2) (K(+)) conformations. The E(1) and E(2) states have different affinities for ligand interaction.

An FTIR spectroscopic study of calf-thymus DNA complexation with Al(III) and Ga(III) cations.

The interaction of calf-thymus DNA with trivalent Al and Ga cations, in aqueous solution at pH = 6-7 with cation/DNA(P) (P = phosphate) molar ratios (r) 1/80, 1/40, 1/20, 1/10, 1/4 and 1/2 was characterized by Fourier Transform infrared (FTIR) difference spectroscopy. Spectroscopic results show the formation of several types of cation-DNA complexes. At low metal ion concentration (r = 1/80, 1/40), both cations bind mainly to the backbone PO2 group and the guanine N-7 site of the G-C base pairs (chelation).

The effect of HCl on the solution structure of calf thymus DNA: a comparative study of DNA denaturation by proton and metal cations using Fourier transform IR difference spectroscopy.

The interaction of HCl with calf thymus DNA was investigated in aqueous solution at pH 7-2 with H+/DNA(P) (P:phosphate) molar ratios (r) of 1/80, 1/40, 1/20, 1/10, 1/4, 1/2, and 1, using Fourier Transform (FTIR) difference spectroscopy. Correlations between spectral changes, proton binding mode, DNA denaturation, and conformational variations are established. A comparison was also made between the ir spectra of denaturated DNA, in the presence of proton and Cu ions with similar cation concentrations.

DNA-carbohydrate interaction. The effects of mono- and disaccharides on the solution structure of calf-thymus DNA.

We report the interaction of calf-thymus DNA with D-glucose, D-fructose, D-galactose and sucrose in aqueous solution at physiological pH with sugar/DNA(P)(P = phosphate) molar ratios (r) of 1/10, 1/5, 1, 5 and 10. FTIR difference spectroscopy was used to characterize the nature of sugar-DNA interaction and correlations between spectral changes and structural variations for both sugar and DNA complexes have been established.

Energy content, storage substances, and construction and maintenance costs of Mediterranean deciduous leaves.

At monthly intervals water content, crude fibre, total and protein nitrogen, sugars, starch, total lipids, ash content and calorific total energy were measured throughout the lifespan of the leaves of the deciduous mediterranean shrubs Pistacia terebinthus L. and Cotinus coggygria Scop. From these data the construction costs and maintenance costs, as well as the construction costs of non-storage compounds and energy expenditure values were calculated.