Solution properties, electrochemical behavior and protein interactions of water soluble triosmium carbonyl clusters
JOURNAL OF ORGANOMETALLIC CHEMISTRY
Authors: Nervi, C; Gobetto, R; Milone, L; Viale, A; Rosenberg, E; Spada, F; Rokhsana, D; Fiedler, J
synthesis and solution chemistry of the water soluble clusters [Os-3(CO)(9)(mu-eta(2)-Bz)(mu-H)L+] (HBz=quinoxaline, L+ - [P(OCH2CH2NMe3)(3)I-3], 1) along with its negatively charged analog [Os-3(Co)(9)(mu-eta(2)-Bz)(mu-H)L-] (L- = [P(C6H4SO3)(3)Na-3], 2) are reported. In addition, we have examined the reduction potentials of the complexes [Os-3(Co)(9)(mu-eta(2)-Bz)(mu-H)L] (HBz = phenanthridine, L = L+ (3); HBz = 5,6 benzoquinoline, L = L+ (4); HBz = 3-amino quinoline, L = L+ (5); HBz = 3-amino quinoline, L = L- (6). The neutral analog of 1 and 2 [Os-3(CO)(9)(mu-eta(2)-Bz)(mu-H) PPh3] (Bz = quinoxaline, 7) was also examined for comparison. Both compounds 1 and 2 show pH dependent NMR spectra that are interpreted in terms of the extent of protonation of the uncoordinated quinoxaline nitrogen which impacts the degree of aggregation of the clusters in aqueous solution. Compound 1 undergoes a reversible le(-) reduction in water while 2 undergoes a quasi-reversible le- reduction at more negative potentials as expected from the difference in charge on the phosphine ligand. Compound 7 undergoes a marginally reversible CV in methylene chloride at a potential intermediate between the positively and negatively charged clusters. The overall stability of the radical anions of 1, 2 and 7 is somewhat less than the corresponding decacarbonyl [Os-3(CO)(10)(mu-eta(2)-Bz)(mu-H)] (HBz-quinoxaline). While complexes I and 2 show reversible le(-) reductions, all the other complexes examined show le(-) and/or two le(-) irreversible reductions in aqueous and non-aqueous solvents. The potentials for these complexes follow expected trends relating to the charge on the phosphine and the pH of the aqueous solutions. The ligand dependent trends are compared with those of the previously reported corresponding decacarbonyls. The interactions of the positively and negatively charged clusters with albumin have been investigated using the transverse and longitudinal relaxation times of the hydride resonances as probes of binding to the protein. Evidence of binding is observed for both the positive and negative clusters but the positive and negative clusters exhibit distinctly different rotational correlation times. Two additional complexes [Os-3(CO)(9)(mu-eta(2)-Bz)(mu-H)L] (HBz = 2-methylbenzimidazole, L = L+ (8); L = L- (10) and HBz = quinoline-4-carboxaldehyde, L = L+ (9); L = L- (11)) are reported in connection with these studies. (C) 2004 Elsevier B.V. All rights reserved.
Mechanisms of human T-Iymphotropic virus type 1 transmission and disease
CURRENT OPINION IN VIROLOGY
Authors: Lairmore, Michael D.; Haines, Robyn; Anupam, Rajaneesh
Human T-Iymphotrophic virus type-1 (HTLV-1) infects approximately 15-20 million people worldwide, with endemic areas in Japan, the Caribbean, and Africa. The virus is spread through contact with bodily fluids containing infected cells most often from mother to child through breast milk or via blood transfusion. After prolonged latency periods, approximately 3-5% of HTLV-1 infected individuals will develop either adult T-cell leukemia/lymphoma, or other lymphocyte-mediated disorders such as HTLV-1-associated myelopathy/tropical spastic paraparesis. The genome of this complex retrovirus contains typical gag, pol, and env genes, but also unique nonstructural proteins encoded from the pX region. These nonstructural genes encode the Tax and Rex regulatory proteins, as well as novel proteins essential for viral spread in vivo such as p30, p12, p13 and the antisense-encoded HTLV-1 basic leucine zipper factor (HBZ). While progress has been made in knowledge of viral determinants of cell transformation and host immune responses, host and viral determinants of HTLV-1 transmission and spread during the early phases of infection are unclear. Improvements in the molecular tools to test these viral determinants in cellular and animal models have provided new insights into the early events of HTLV-1 infection. This review will focus on studies that test HTLV-1 determinants in context to full-length infectious clones of the virus providing insights into the mechanisms of transmission and spread of HTLV-1.