Biological activity of hemoprotein nitrosyl complexes

Chemical and biological functions of hemoprotein nitrosyl complexes as well as their photolysis products are discussed in this review. Chemical properties of nitric oxide are discussed, and major chemical reactions such as interaction with thiols, free radicals, and transition metals are considered. Specific attention is paid to the generation of hemoprotein nitrosyl complexes. The mechanisms of nitric oxide reactions with hemoglobin and cytochrome c and physicochemical properties of their nitrosyl complexes are discussed. A review of photochemical reactions of nitrosyl complexes with various ligands is given. Finally, we observe physiological effects of visible radiation on hemoprotein nitrosyl complexes: smooth muscle relaxation and reactivation of mitochondrial respiration.     

Biological activity of ruthenium nitrosyl complexes

Nitric oxide plays an important role in various biological processes, such as neurotransmission, blood pressure control, immunological responses, and antioxidant action. The control of its local concentration, which is crucial for obtaining the desired effect, can be achieved with exogenous NO-carriers. Coordination compounds, in particular ruthenium(III) and (II) amines, are good NO-captors and -deliverers. The chemical and photochemical properties of several ruthenium amine complexes as NO-carriers in vitro and in vivo have been reviewed. These nitrosyl complexes can stimulate mice hippocampus slices, promote the lowering of blood pressure in several in vitro and in vivo models, and control Trypanosoma cruzi and Leishmania major infections, and they are also effective against tumor cells in different models of cancer. These complexes can be activated chemically or photochemically, and the observed biological effects can be attributed to the presence of NO in the compound. Their efficiencies are explained on the basis of the [Ru^IINO⁺]³⁺/[Ru^IINO⁰]²⁺ reduction potential, the specific rate constant for NO liberation from the [RuNO]²⁺ moiety, and the quantum yield of NO release.     

Hydrodynamic properties of macromolecular complexes. I. Translation

We have developed an improved theory for calculating the translational frictional coefficients of rigid macromolecular complexes composed of unequal spherical subunits. The Yamakawa hydrodynamic interaction tensor, which improves on the Oseen tensor by taking account of the finite sizes of the frictional subunits, has been generalized to accomodate nonidentical subunits. Iterative numerical methods are described for solving the set of simultaneous hydrodynamic interaction equations, thus avoiding preaveraging. The theory is applied to prolate ellipsoids of revolution, to lollipops, and to dumbbells, and comparison is made with earlier, more approximate theories.     

Biological activity of sulphur ylides. I. Antimicrobial properties of some new carbonyl stabilized sulphonium ylides

Antimicrobial properties of some new carbonyl stabilized sulphonium ylides have been tested against two bacteria Staphylococcus aureus, Escherichia coli and two fungi Alternaria alternata and Curvularia lunata. The potent antifungal activity of these compounds suggest their practical applications in fungicidal formulations and other pharmacological preparations.     

Comparative characteristics of soluble and membrane brain aminopeptidases. I. Isolation, physico-chemical properties, catalytic activity

The methods were worked out for isolating of the bovine brain soluble and membrane-bound aminopeptidases in highly purified state. One of the stages involved a biospecific-type chromatography on aminohexyl-Sepharose. Both enzymes were found to have equal molecular masses (ca. 100-107 kD) and isoelectric points (pI 4,6). None of the enzymes possessed a subunit structure. Both aminopeptidases were inactivated by omicron-phenanthroline and by an SH-reagent, p-hydroxymercuribenzoate. The catalytic constants for the hydrolysis of a specific substrate, L-leucine p-nitroanilide, were identical for the two enzymes. So far no differences in the physico-chemical or enzymatic properties of the soluble and membrane-bound enzymes were disclosed.     

Spectroscopic properties of complexes of acridine orange with glycosaminoglycans. I. Soluble complexes.

The interaction of acridine orange with dermatan and chondrotin sulfates results in the formation of complexes containing bound dye molecules ordered into dissymmetric arrays. Complexes containing an excess of available disaccharide residues compared to dye are completely soluble, and exhibit biphasic circular dichroism bands. Analysis of the dependence of the extrinsic circular dichrosim on dye aggregation indicates the presence of extended dye stacks bound to the glycosaminoglycan. Complexes formed in solutions containing an excess of dye are only partially soluble, and exhibit circular dichroism spectra having band shifts and intensity changes relative to the soluble complexes. The latter complexes show a sharp drop in induced circular dichroism with temperature, due to a cooperative change in the structure of the complex. The structural order of the dye–glycosaminoglycan complex may differ from the intrinsic structure of the glycosaminoglycan itself in dilute solution.     

Conformation properties and enzymatic activity of pancreatic ribonuclease in soluble complexes with sodium dextran sulfate

Effect of complex formation with dextran sulfate (DS) (substitution degree 1.3, molecular mass 500 thousand) on RNAse enzymic activity. its spatial structure and conformation stability was studied. Hydrolytic activity of the enzyme in complex in inhibited already at small additions of DS, while the transferase one is changed only at a great excess of the polyelectrolyte. It has been shown by CD spectra that no notable conformation changes proceed in the enzyme during complex formation, although the enzyme turns destabilized to the denaturing effect of heat at the expense of strengthened interactions between DS and RNAse during its denaturation. Thus the inhibition of hydrolytic activity in the complex is primarily related to limitations for the formation of the enzyme-substrate complex on polyelectrolyte charged likely with the substrate, and not to the protein conformation changes.