Roles of copper and O(2) in the radiation-induced inactivation of T7 bacteriophage

The effect of copper on the radiation damage induced in T7 bacteriophage has been investigated. The phages were gamma-irradiated and the effects of copper(II) ions in the presence of various additives and radical scavengers were examined in an attempt to better understand the effect of transition metal ions on the role of free radicals, particularly superoxide, in biological damage. The present work extends a study previously done on isolated enzyme to a whole biological entity. Copper(II) ions even at very low concentrations enhanced the lethal effect of radiation. This sensitization was observed in both the presence and the absence of oxygen. The effect of copper could be reverted by chelating agents such as EDTA or 1,10-phenanthroline. Hydrogen peroxide enhanced the sensitizing effect of copper, though little if any protection was provided by catalase or SOD. High molecular weight scavengers of free radicals in the presence of both copper(II) and hydrogen peroxide had no protective effect. (This is in contrast to metal-free systems where, although such scavengers are incapable of penetrating the phages, they protect them against inactivation.) These scavengers, without added H2O2, afforded only slight protection to the irradiated phages in the presence of Cu. Low molecular weight scavengers of free radicals reduced but did not eliminate the sensitizing effect of copper. The sensitizing effect of copper was also observed with other T-odd phages, but not with the T-even series. Copper(II) ions under similar experimental conditions did not sensitize T4 or T2 phages but rather had a protective effect. The results are interpreted in terms of a site-specific Fenton mechanism according to which the binding of the metal ion to the phages is a prerequisite for the occurrence of the biological damage. The results also indicate that most of the copper effect is endogenous. This is in accord with the failure of copper to sensitize the T-even phages, which differ by the rigidity and permeability of their outer coat structures.     

Application of FTIR microscopy for the characterization of malignancy: H-ras transfected murine fibroblasts as an example.

Recently, microscopic FTIR is widely used in the field of biology and medicine. FTIR can detect biomolecular changes in the cells and tissues responsible for various disorders. In this report, we characterize the H-ras transfected fibroblasts and its normal control using microscopic FTIR. The intensity of the normal fibroblasts was higher than that of H-ras transfected fibroblasts. Our studies showed significant differences occur in the concentration of vital metabolites upon transformation. The DNA and carbohydrates level decreased in the transformed cells compared to the controls. A linear correlation could be found between the levels of carbohydrates and phosphate, while the RNA/DNA ratio varied inversely with glucose/phosphate levels.     

Reaction of nitric oxide with heme proteins: studies on metmyoglobin, opossum methemoglobin, and microperoxidase

Kinetic and EPR studies show that the first step in the reaction of NO with ferric myoglobin, opossum hemoglobin, and microperoxidase is the reversible formation of the H-NO complex: H + NO in equilibrium H-NO (where H = Mb+, or Hb+ OP, or MP+). The NO-combination rates are markedly affected by the presence or absence of the distal histidine. The distal histidine significantly reduces the NO-combination rates, perhaps by interaction between the distal histidine and the ferric iron. Thus the beta-chains of Hb+ OP and metmyoglobin show similar combination rates. In the absence of a distal histidine, the NO-combination rates in the alpha-chains of Hb+ OP are much faster and similar to those observed for the five-coordinate heme in microperoxidase. The loss of a water molecule from the six-coordination site is assumed to be the rate-limiting step.     

Lyme Disease Associated with Alzheimer’s Disease

This case report discusses a patient with co-occurring neuroborreliosis and Alzheimer’s disease (AD). Although no claim is made for causality nor is there objective evidence that spirochetes are involved in AD, co-infection may exacerbate the symptoms of either neuroborreliosis or AD. Much is to be learned about the role of spirochetes in degenerative central nervous system disease.     

Retinal-Protein Interactions in Halorhodopsin from Natronomonas pharaonis: Binding and Retinal Thermal Isomerization Catalysis

Halorhodopsin from Natronomonas pharaonis (NpHR) is a member of the retinal protein group and serves as a light-driven chloride pump in which chloride ions are transported through the membrane following light absorption by the retinal chromophore. In this study, we examined two main issues: (1) factors controlling the binding of the retinal chromophore to the NpHR opsin and (2) the ability of the NpHR opsin to catalyze the thermal isomerization of retinal isomers. We have revealed that the reconstitution process of pharaonis HR (NpHR) pigment from its apoprotein and all-trans retinal depends on the pH, and the process has a pK_a of 5.8 ± 0.1. It was proposed that this pK_a is associated with the pK_a of the lysine residue that binds the retinal chromophore (Lys256). The pigment formation is regulated by the concentration of sodium chloride, and the maximum yield was observed at 3.7 M NaCl. The low yield of pigment in a lower concentration of NaCl (< 3 M) may be due to an altered conformation adopted by the apomembrane, which is not capable of forming the pigment. Unexpectedly and unlike the apomembrane of bacteriorhodopsin, NpHR opsin produces pigments with 11-cis retinal and 9-cis retinal owing to the thermal isomerization of these retinal isomers to all-trans retinal. The isomerization rate depends on the pH, and it is faster at a higher pH. The pK_a value of the isomerization process is similar to the pK_a of the binding process of these retinals, which suggests that Lys256 is also involved in the isomerization process. The isomerization is independent of the sodium chloride concentration. However, in the absence of sodium chloride, the apoprotein adopts such a conformation, which does not prevent the isomerization of retinal, but it prevents a covalent bond formation with the lysine residue. The rate and the thermodynamic parameter analysis of the retinal isomerization by NpHR apoprotein led to the conclusion that the apomembrane catalyzes the isomerization via a triplet mechanism.     

SOBP is mutated in syndromic and nonsyndromic intellectual disability and is highly expressed in the brain limbic system

Intellectual disability (ID) affects 1%-3% of the general population. We recently reported on a family with autosomal-recessive mental retardation with anterior maxillary protrusion and strabismus (MRAMS) syndrome. One of the reported patients with ID did not have dysmorphic features but did have temporal lobe epilepsy and psychosis. We report on the identification of a truncating mutation in the SOBP that is responsible for causing both syndromic and nonsyndromic ID in the same family. The protein encoded by the SOBP, sine oculis binding protein ortholog, is a nuclear zinc finger protein. In mice, Sobp (also known as Jxc1) is critical for patterning of the organ of Corti; one of our patients has a subclinical cochlear hearing loss but no gross cochlear abnormalities. In situ RNA expression studies in postnatal mouse brain showed strong expression in the limbic system at the time interval of active synaptogenesis. The limbic system regulates learning, memory, and affective behavior, but limbic circuitry expression of other genes mutated in ID is unusual. By comparing the protein content of the +/jc to jc/jc mice brains with the use of proteomics, we detected 24 proteins with greater than 1.5-fold differences in expression, including two interacting proteins, dynamin and pacsin1. This study shows mutated SOBP involvement in syndromic and nonsyndromic ID with psychosis in humans.