Optical biosensor and scanning probe microscopy studies of cytochrome P450 interactions with redox partners and phospholipid layers

Peripheral nerve targeting by procaine-conjugated ribavirin-loaded dual drug nanovesicle

AIM

Procaine that is able to reach the peripheral nervous system (PNS) was conjugated as a ligand with lipid nanovesicle and loaded with ribavirin (a broad spectrum antiviral drug incapable of entering the PNS on its own) to target the PNS with a dual-drug effect.

MATERIALS & METHODS

Different physicochemical characterizations, γ-scintigraphy and electromyography of the developed nanovesicle were conducted.

RESULTS

Marked capability of the optimized radiolabeled formulation to target PNS was observed in rats. Electromyography signals were reduced after treatment with the formulation on conscious rats.

CONCLUSION

The developed nanocarrier can deliver drug successfully at the PNS and reduce excitation of the nerve and thus give a better therapeutic option for treatment of various diseases and disorders of the PNS.

[Visualization and identification of hepatitis C viral particles by atomic force microscopy combined with MS/MS analysis]

Possibility of detection and identification of hepatitis C viral particles with mass spectrometry (MS) in combination with atomic force microscopy (AFM) had been investigated. AFM/MS approach is based on two technologies: (1) AFM-biospecific fishing that allows to detect, concentrate from solution and to count protein complexes on a surface of AFM-nanochip; (2) mass spectrometric identification of these complexes. AFM-biospecific fishing of HCVcoreAg from solution was carried onto surface of AFM-nanochips with immobilized anti-HCVcoreAg. It was shown that HCVcoreAg/anti-HCVcore(im) complexes were formed onto AFM-nanochips in quantity sufficient for mass spectrometric identification. Thus, AFM/MS approach allows to identify fragments of hepatitis C virus fished onto a surface of AFM-nanochip from serum.

Application of AFM and optical biosensor for investigation of complexes formed in P450-containing monooxygenase systems

Atomic force microscopy (AFM) allows to visualize and count the individual protein molecules and their complexes within multiprotein systems. On the other hand, optical biosensor (OB) provides information on complex formation kinetics as well as complex lifetime (τ(LT)) and affinity. Comparison of complex lifetime τ(LT) with the time required for enzyme's catalytic cycle (τ(cat)) enables to characterize productive complexes and distinguish them from non-productive ones. Both these approaches were applied for the analysis of the three cytochrome P450-containing monooxygenase systems: cytochrome P450 101, cytochrome P450 11A1 and cytochrome P450 2B4. By using AFM, the formation of binary and ternary protein complexes was registered in all the three systems. OB analysis enabled to kinetically characterize these binary and ternary complexes. It was shown that the binary complexes putidaredoxin reductase (PdR)/putidaredoxin (Pd) and Pd/cytochrome P450 101 (P450 101) formed within the P450 101 system and, also, the binary complexes adrenodoxin reductase (AdR)/adrenodoxin (Ad) and Ad/cytochrome P450 11A1 (P450 11A1) formed within the P450 11A1 system are non-productive (deadlock). At the same time, the ternary PdR/Pd/P450 101 and AdR/Ad/P450 11A1 complexes proved to be productive. The binary cytochrome P450 reductase (Fp)/cytochrome P450 2B4 (2B4) complexes and the ternary Fp/2B4/cytochrome b5 (b5) complexes formed within P450 2B4 system were productive.

Analytical nanobiotechnology for medicine diagnostics

The review is concerned with the state-of-the-art and the prospects of development of nanotechnologies in clinical proteomics. Nanotechnology in clinical proteomics is a new medical research direction, dealing with the creation and application of nanodevices for performing proteomic analyses in the clinic. Nanotechnological progress in the field of atomic force microscopy makes it possible to perform clinical studies on the revelation, visualization and identification of protein disease markers, in particular of those with the sensitivity of 10(-17) M that surpasses by several orders the sensitivity of commonly adopted clinical methods. At the same time, implementation of nanotechnological approaches into diagnostics allows for the creation of new diagnostic systems based on the optical, electro-optical, electromechanical and electrochemical nanosensoric elements with high operating speed. The application of nanotechnological approaches to creating nanopore-based devices for express sequencing of the genome is discussed.

Conformational transitions and redox potential shifts of cytochrome P450 induced by immobilization

Cytochrome P450 (P450) from Pseudomonas putida was immobilized on Ag electrodes coated with self-assembled monolayers (SAMs) via electrostatic and hydrophobic interactions as well as by covalent cross-linking. The redox and conformational equilibria of the immobilized protein were studied by potential-dependent surface-enhanced resonance Raman spectroscopy. All immobilization conditions lead to the formation of the cytochrome P420 (P420) form of the enzyme. The redox potential of the electrostatically adsorbed P420 is significantly more positive than in solution and shows a steady downshift upon shortening of the length of the carboxyl-terminated SAMs, i.e., upon increasing the strength of the local electric field. Thus, two opposing effects modulate the redox potential of the adsorbed enzyme. First, the increased hydrophobicity of the heme environment brought about by immobilization on the SAM tends to upshift the redox potential by stabilizing the formally neutral ferrous form. Second, increasing electric fields tend to stabilize the positively charged ferric form, producing the opposite effect. The results provide insight into the parameters that control the structure and redox properties of heme proteins and contribute to the understanding of the apparently anomalous behavior of P450 enzymes in bioelectronic devices.

Interactions of mammalian cytochrome P450, NADPH-cytochrome P450 reductase, and cytochrome b(5) enzymes

An immobilized system was developed to detect interactions of human cytochromes P450 (P450) with the accessory proteins NADPH-P450 reductase and cytochrome b(5) (b(5)) using an enzyme-linked affinity approach. Purified enzymes were first bound to wells of a polystyrene plate, and biotinylated partner enzymes were added and bound. A streptavidin-peroxidase complex was added, and protein-protein binding was monitored by measuring peroxidase activity of the bound biotinylated proteins. In a model study, we examined protein-protein interactions of Pseudomonas putida putidaredoxin (Pdx) and putidaredoxin reductase (PdR). A linear relationship (r(2)=0.96) was observed for binding of PdR-biotin to immobilized Pdx compared with binding of Pdx-biotin to immobilized PdR (the estimated K(d) value for the Pdx.PdR complex was 0.054muM). Human P450 2A6 interacted strongly with NADPH-P450 reductase; the K(d) values (with the reductase) ranged between 0.005 and 0.1muM for P450s 2C19, 2D6, and 3A4. Relatively weak interaction was found between holo-b(5) or apo-b(5) (devoid of heme) with NADPH-P450 reductase. Among the rat, rabbit, and human P450 1A2 enzymes, the rat enzyme showed the tightest interaction with b(5), although no increases in 7-ethoxyresorufin O-deethylation activities were observed with any of the P450 1A2 enzymes. Human P450s 2A6, 2D6, 2E1, and 3A4 interacted well with b(5), with P450 3A4 yielding the lowest K(d) values followed by P450s 2A6 and 2D6. No appreciable increases in interaction between human P450s with b(5) or NADPH-P450 reductase were observed when typical substrates for the P450s were included. We also found that NADPH-P450 reductase did not cause changes in the P450.substrate K(d) values estimated from substrate-induced UV-visible spectral changes with rabbit P450 1A2 or human P450 2A6, 2D6, or 3A4. Collectively, the results show direct and tight interactions between P450 enzymes and the accessory proteins NADPH-P450 reductase and b(5), with different affinities, and that ligand binding to mammalian P450s did not lead to increased interaction between P450s and the reductase.