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<p> Electrospray ionization (ESI) is a premier method for volatilizing and ionizing biological analytes for mass spectrometry. In conventional mass spectrometry (MS), the spectrum of mass-to-charge ratio (<i>m/z</i>) for an ensemble of ions is measured. ESI produces a distribution of charges for each ionized species, and the mass of each species is determined by assigning a charge state to each peak in the <i>m/z</i> spectrum. These peaks are difficult to resolve for species above the 100-kDa range because of peak broadening and shifting due to salt adducts, incomplete desolvation, and intrinsic heterogeneity. Without resolved charge states, the mass cannot be determined. Charge detection mass spectrometry (CDMS) offers a solution to this problem. </p><p> In CDMS, both the <i>m/z</i> and the charge are measured simultaneously for individual ions. Multiplying those measurements for each ion yields the mass. Thus, there is no need for charge state resolution in an m/z spectrum. CDMS can therefore be used to measure the masses of extremely heavy and heterogeneous analytes far beyond the capabilities of conventional MS. This comes at the cost of efficiency, since single ions are measured serially, and resolution, since the charge measurement historically has been imprecise in CDMS. </p><p> Here we report a nearly perfect charge measurement in CDMS by analyzing each ion for 3 s in an electrostatic ion trap and implementing a novel analysis method. Then we discuss spontaneous mass and charge losses of trapped ions. Finally, we discuss multiple applications of CDMS to bacteriophage P22. P22 capsids assemble into <i>T = 7</i> &lsquo;procapsids&rsquo; with the assistance of a distribution of scaffolding proteins; we report the typical width of that distribution. Next we report our observation of mass loss in P22 procapsids over the course of weeks due to precipitation of scaffolding proteins. Then we discuss how the charge on electrosprayed P22 capsids allows us to distinguish morphologies of P22 capsids. Finally, we report an accurate mass measurement of the infectious P22 phage, a >50 MDa particle containing nucleic acid and nine kinds of protein.</p>

<p> Cell membranes have been shown to be able to change the conformation of proteins/peptides. However, the structure of the cell membrane is complicated and has been divided to three regions: the hydrophobic region containing alkyl chains, the hydrophilic head group, and the hydration layer, or lipid-water interface, which exists between the hydrophilic head group and the bulk water solution, but with lower dielectric constant compared with fully hydrated water. The air-water interface has been used to mimic the structure of the hydration layer because of their similar dielectric constant.1,2 Some proteins were found to form a stable Langmuir monolayer and accumulate at the air-water interface. For example, ?-synclein, a membrane protein containing 140 amino acids, is unstructured in aqueous solution but changes its conformation to &alpha;-helix at the air-water interface. This incites interest to investigate short motifs of &alpha;-helix to form a stable Langmuir monolayer at the air-water interface. In this thesis, a peptide with sequence of YAAAA(KAAAA)4 (referred as Pep25 hereafter) was used as a model peptide of &alpha;-helix to spread at the air-water interface, because our group has determined the conformation of Pep25 in residue level by the 13C isotope-edited FTIR. Langmuir monolayer technique together with IRRAS showed that Pep25 does not form a typical Langmuir monolayer at the interface. Potential plans to make Pep25 to form a stable monolayer are also discussed in this thesis.</p>

<p> The well-established principles of organic photochemistry, offer chemists the fundamental understanding and tools for studying light induced chemical transformations. Employing visible light for photocatalysis, one can design and develop benign routes for the synthesis of new organic materials. In our present investigation, we have developed novel <i>N-N</i> bond based compounds for visible light mediated phototransformations. We have presented synthesis for targeting achiral/chiral <i>N-N</i> bond based compounds and their study for various light driven applications. To name a few applications, these compounds have shown to react smoothly under visible light, metal-free conditions for classical photoreactions, chloromethylation, asymmetric photocyclization and photopolymerization. A diverse range of compounds has shown to react smoothly to afford products in high yields. </p><p> The scope of this methodology has been evaluated for both intermolecular and intramolecular reactions. Our work benefits from the ability of these compounds to undergo desired phototransformation in both solution and in crystalline media. We have provided photochemical and photophysical details that corroborates our experimental findings and highlights the role of excited state reactivity of the novel N-N bond based compounds. This thesis will be an effort to make chemists familiarize with potential of these compounds in light induced reactions. </p>

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A range of analytical techniques were investigated and compared for the determination of platinum group metals in plant tissues. These included ICP, DC arc AES and PlXE. Particular attention was paid to problems associated with determination by ETA AAS and INAA. PIXE was suitable as a routine method and gave results in good agreement with those from INAA. The ICP method was satisfactory only at relatively high concentrations. The biological effects of platinum group metals on Eichhornia crassipes were studied. At an applied metal concentration of 10ppm, the relative toxicity was found to be: Pt²⁺ &ap; Pd²⁺ > Os⁴⁺ &ap; Ru³⁺ > Ir³⁺ > Pt⁴⁺ " Rh³⁺. The metals were deposited mostly in plant roots though varying amounts were transported to the tops. Toxic symptoms of Pt²⁺ complexes included the appearance of reddish-brown streaks in the leaves, whilst Rh³⁺ appeared to exhibit a tonic effect. In contrast, the grass Setaria verticillata was growth stimulated by Pt²⁺ at low levels. Two complexed forms of platinum were investigated further because of the difference in relative toxicity. Platinum applied as the anti-tumour complex cis [Pt(NH₃)₂Cl₂] was found to be toxic at high levels. When applied at low levels some 47.9% of the platinum in the leaves was associated with alpha-cellulose and lignin; 16.1% was removed by the proteolytic enzyme pronase, and 20.8% found with water soluble pectates. A similar distribution was found in the floats of Eichhornia crassipes and in the plant roots the values were 35%, 3-5% and 14.2% respectively. In the roots however, a further 23.1% was removed with low molecular weight alcohol soluble materials and 12.0% with polar water soluble materials. The amino acid constituents of control and platinum treated plants are also presented. When applied as Pt⁴⁺, platinum appeared relatively non-toxic. Analytical electron micrographs revealed Pt deposits concentrated in the epidermis of the root with lesser amounts extending up to the endodermis. XPS confirmed the deposits on the root surface as Pt and the binding energy suggests it is Pt4+. Ruthenium also has been detected in the epidermis of Ru treated root samples.

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