RNA aptamers are in vitro sequences of RNA that have a high affinity for their target ligand. They have applications in therapeutics, biosensors and molecular machines. While the practical applications of aptamers are increasing, it is important to study their structure and thermodynamics to improve the understanding of these molecular tools. The malachite green aptamer (MGA) provides a model system to study the interactions between aptamer and ligand that do not involve hydrogen bonding between ligand and receptor. While the original application of this aptamer was abandoned, study of the MGA binding pocket revealed an electronegative environment that was harnessed for catalysis. MGA binding also supported the notion that aptamers bind by adaptive binding. Adaptive binding is the ability of molecules to mold themselves around the structure of a ligand thereby incorporating it into their three-dimensional fold. To further expand our understanding of MGA binding and to clarify conflicting reports of affinities, we conducted isothermal calorimetry binding studies. The results reveal that the entropy of complex formation plays a large role in determining binding affinity and ligand specificity. This data combined with previous structural studies show that metal ions are required to stabilize the complexes with non-native ligands, whereas, the complex with the original selection target is stable at low salt and in the absence of divalent metal ions. Next, competitive binding studies using isothermal titration calorimetry were conducted with the aim of understanding the adaptive nature of RNA. The results of these studies reveal that there are limits to the adaptability of the aptamer. Binding of one type of ligand reduces the affinity of the aptamer pocket to a differently shaped ligand, even if this second ligand has a significantly higher affinity. The ability of MGA to change ligand preference based on buffer conditions, and the previously reported catalysis suggested that RNA may have a potential supporting multiple functions in the same molecule. To investigate this possibility we attempted to select an aptamer that supports both ligand binding and catalysis. By conducting both a DNA and RNA selection we hoped to add to the iv collection of DNA and RNA aptamers selected for the same target. There are currently too few of these to determine if any correlation can be made between DNA and RNA sequences that bind the same target. The target of the selection was fluorescein diacetate (FDA), which was chosen with the aim that it would allow the exploration of the inherent potential of the selected aptamer to cleave FDA to fluorescein. The RNA selection proved to be more successful and an attempt was made to characterize the binding of the aptamer to its target fluorescein diacetate. Unfortunately there were complications with the binding assays, but future work is proposed that should address the issues. In order to expand the MGA catalytic repertoire attempts were made to synthesize new ligands that could exploit the catalytic potential of the MGA binding pocket. Unfortunately these attempts were unsuccessful, however further attempts are recommended. The MGA used in this study was transcribed in vitro using T7 RNA polymerase. This process is known to add extra nucleotides to the end of the transcription product. Attempts were made to eliminate the n+1 product by introducing a ribozyme or DNAzyme. These were met with difficulties resulting in low yield, however mass spectrometry revealed that n and n+1 MGA bind to ligand. This, along with secondary structure prediction suggests that MGA n+1 behaves the same as n. Overall, the results presented here provide insights into the capabilities of RNA aptamers with respect to ligand binding and catalysis.

Heparin binding (HB) proteins mediates a wide range of important cellular processes, which makes this class of proteins biopharmaceutically important. Engineering HB proteins could bring many advantages, but it necessitates cost effective and efficient purification methodologies compared to the currently available methods. One of the most important classes of heparin binding protein is the fibroblast growth factors (FGFs) and its receptors (FGFRs). In this study, we report an efficient off-column purification of FGF-1 from soluble fractions and purification of the D2 domain of FGFR from insoluble inclusion bodies, using a weak amberlite cation (IRC) exchanger. This approach is an alternative to conventional affinity column chromatography, which exhibit several disadvantages, including time-consuming experimental procedures and regeneration and results in high cost for production of recombinant proteins. Authenticity of the purified proteins was verified by SDS-PAGE and MALDI mass spectrum analysis. Results of the heparin binding chromatography and steady state fluorescence experiments showed that the FGF-1 and the D2 are in a native biologically active conformation. The findings of this study will not only aid an in-depth investigation of this class of proteins but will also provide avenues for inexpensive and efficient purification of other important biological macromolecules.

This thesis is about protein profiling in serum and plasma using antibody suspension bead arrays for the analysis of biobanked samples and in the context of prostate cancer biomarker discovery. The influence of sample preparation methods on antibody based protein profiles were investigated (Papers I-III) and a prostate cancer candidate biomarker identified and verified (Papers III-V). Furthermore, a perspective on the research area affinity proteomics and its’ employment in biomarker discovery, for improved understanding and potentially improved disease diagnosis, is provided. Paper I presents the results of a comparative plasma and serum protein profiling study, with a targeted biomarker discovery approach in the context of metabolic syndrome. The study yielded a higher number of significant findings and a low experimental variability in blood samples prepared as plasma. Paper II investigated the effects from post-centrifugation delays at different temperatures prior sample storage of serum and plasma samples. Minor effects were found on the detected levels of more than 300 predicted or known plasma proteins. In Paper III, the detectability of proteins in plasma was explored by exposing samples to different pre-analytical heat treatments, prior target capture. Heat induced epitope retrieval was observed for approximately half of the targeted proteins, and resulted in the discovery of different candidate markers for prostate cancer. Several antibodies towards the prostate cancer candidate biomarker CNDP1 were generated, epitope mapped and evaluated in a bead based sandwich immunoassay, as presented in Papers IV and V. Furthermore, the developed sandwich immunoassay targeting multiple distinct CNDP1 epitopes in more than 1000 samples, confirmed the association of CNDP1 levels to aggres- sive prostate cancer and more specifically to prostate cancer patients with regional lymph node metastasis (Paper V). As an outcome of the present investigations and in parallel to studies within the Biobank profiling research group, valuable lessons from study design and multiplex antibody analysis of plasma within biomarker discovery to experimental, technical and biological verifications have been collected. / <p>QC 20130821</p>

This ethnographic study investigated the interactions between the musical lives of adolescents and school music-learning culture in a suburban high school. Participants included two music teachers and seven adolescents. Framed within a symbolic interactionist perspective (Blumer, 1969), data were collected via methods consistent with qualitative inquiry, including an innovative data collection technique utilizing music elicitation interviews with adolescents. Findings emerged from the data via thematic analysis (Grbich, 2007). Findings indicate limited interactions between the musical lives of adolescents and school music-learning culture because participants portrayed and experienced a dichotomy between the musical assumptions and practices inside and outside of school. Interactions occurred when participants engaged in sharing musical capital that overcame segmentation among music learning, out-of-school experience, and elective participation in secondary school music programs. Supporting findings indicate that the school music-learning culture derived from teachers' negotiating between two major influences: 1) their own musical values, which were based on their musical backgrounds and the long-established professional tradition of formal performance emphases in school music programs; and 2) the musical values of their students. Adolescents self-defined their musical lives as largely informal musical activities commonly experienced outside of school. They expressed a wealth of personal musical knowledge and described their affinity for music across four dimensions: 1) expression and feeling, 2) relevance, 3) quality in artistry and craftsmanship, and 4) diversity. Three themes describe how adolescents’ personal relationships with music influenced their beliefs and choices regarding music participation and learning: 1) musical roots: nurturing personal and social connections with music, 2) motivated learning: seeking relevance and challenge, and 3) finding a voice: striving toward musical independence. Findings indicate that music teachers may enhance interactions between adolescents’ musical lives and school music-learning culture by acknowledging students’ musical engagement outside of school, honoring their personal musical knowledge and interests, and making them collaborators in developing music-learning models rooted in their affinity for, and personal relationships with, music.

The paradigm of drug discovery have been to find the strongest possible binder to the target by high-throughput screening (HTS) but high affinity interactions are related to low kinetic off rates and thus result in severe side-effects and non-approved drugs. Lead molecules working in a transient manner (KD &gt; µM) will allow for rapid off rates and possibly less side-effects. In this study the peak profile method applied to weak affinity chromatography (WAC) was evaluated as a simple way to provide the kinetics of the interaction and thereby allowing for high-throughput determinations. In the peak profile formula all band-broadening effects except the stationary mass transfer is subtracted which simplifies the calculations for the kinetics of the interaction tremendously. The technique was evaluated by screening of 3 different benzamidines at 3 linear flow-rates using zonal chromatography and human α-thrombin as immobilized target protein. The kinetics of the interaction could unfortunately not be determined. This was possibly due to the flow-rates not being high enough as indicated by a low critical ratio (η &lt; 1). Higher flow-rates would increase the contribution to band-broadening due to kinetic effects but would also require more precise estimation of peak variance.

Abstract It is well known that geographical distances between nations cause differences in cul-tural resemblances as well as affinity. Defined, affinity is inheriting similarities between nations in familiarity, language and mutual understanding. It cause variations in the uni-lateral trade volume flowing towards the destination countries and can be estimated by a traditional gravity model (GM). So far Swedish affinity towards Czech Republic (CZ) has remained unexplored. Hence, this paper investigates Swedish firm´s export perfor-mance and affinity towards CZ, both through the aggregate export and the extensive margin (average number of exporters). The investigation aims to seek clarification of what particular factors influence unilateral export towards CZ as well as stronger affini-ty in contrast to similar markets. To answer those questions, a one sided GM is re-gressed on two gravity equations, covering panel data for 177 destination countries from year 1997 to 2006. Results are in line with the expected behavior of the GM and show evidently; distance as well as land lock features have negative effects on unilateral ex-ports to CZ. Additionally, evidence of positive influence on unilateral export is found for GDP and familiarity to the nation. Both regressions for the gravity equations are showing high goodness of fit for the panel data. Findings of positive residuals in both the equations conclude that Swedish export have stronger affinity to CZ and solider country characteristics than its resembling countries Slovenia and Slovakia. However, positive residuals also indicate larger export flows to CZ than motivated by the tradi-tional GM coefficients. Various explanations are suggested as origins for those, such as differences in purchasing power and regions, were Prague was found to be the most suitable option for export and other regions rather for outsourcing possibilities.

We have previously used a two-dimensional fluorescence difference gel electrophoresis protein expression with matrix-assisted laser desorption ionization of mass spectrometry to identify the serum proteomic profiles before and after the Tai Chi exercise in normal adults (Yang & Chang, et al. Clin Chem 56:127, 2010). However, the high abundant serum proteins in seyal samples might interfere the discovery of low abundance proteins in two-dimensional electrophoresis, but these low abundant proteins may play an important role on human physiology. Therefore, we looked for another way to resolve this complex issue. After multiple attempts, we chose a commercial affinity column to exclude 14 kinds of high-abundance proteins before analyses of serum proteomic displays. This column could be fit into a fast liquid chromatography separation of purified proteins and eluted for low abundant proteins. The low abundant proteins were first expressed by one-dimensional gel electrophoresis of proteins followed by a series of gel cut down for in-gel digestion by trypsin and subject to nano-liquid chromatography with electrospray ionization tandem mass spectrometry analysis (nano-LC ESI MS/MS ). The results obtained by software analysis were subject to its functional pathways analysis. We analysed 3 comparisons of the protein displays including differences between normal adults before and after exercise, differences of normal adults and diabetic patients before and after exercise. Experiments were next performed to validate the most significant difference of proteins between each category by enzyme-linked immunoassay. Results showed that dipeptidyl peptidase 4 (DPP4) and neutrophil gelatinase-associated lipocalin (NGAL) proteins were significantly higher in diabetic patients than in normal adults ( P values were 0.011 and less than 0.001), while the prolactin-inducible protein (PIP) was higher in normal adults than in diabetic patients after exercise (P value of 0.042). To our knowledge, decrease of DPP4 in type 2 diabetes has been shown to reduce blood sugar and improve the immunity; and NGAL has been confirmed to be an indicator for early diagnosis of acute kidney injury. Therefore, we have identified certain functional proteomic markers in normal and diabetic patients after Tai Chi exercise. This study model with exclusion of high-abundance serum proteins is a useful mode for identifying immune and metabolic marker with and without.

The purpose of the study is to purify human growth hormone from the fermentation broth by affinity chromatography. For this purpose, human growth hormone specific oligonucleotide aptamers are selected among an aptamer library / selected oligonucleotides were synthesized and used as ligands. Effect of pH on ligand-human growth hormone complex formation was investigated and the highest complex formation was obtained at pH= 7.0. Human growth hormone is separated from the fermentation broth with 99.8% purity and 41% overall yield. The equilibrium data obtained was described by Langmuir type isotherm where saturation constant (q0) and affinity constant (K) are calculated as 0.338 mg hGH/&igrave / mol aptamer and 0.059 mg hGH/ml, respectively. Further, equilibriumdata obtained using aptamer affinity column was described by Langmuir type isotherm where saturation constant (q0) and affinity constant (K) are 0.027 mg hGH/&igrave / mol aptamer and 1.543 mg hGH/ml, respectively. It is possible that, selected aptamer can be used for purification of bulk amounts of recombinant human growth hormone by using aptamer affinity chromatography.

<p>The recent development of methods for constructing andhandling large collections (libraries) of proteins, from whichvariants with desired traits can be isolated, hasrevolutionized the field of protein engineering. Key elementsof such methods are the various ways in which the genotypes(the genes) and the phenotypes (the encoded proteins) arephysically linked during the process. In one section of thework underlying this thesis, one such technique (phagedisplay), was used to isolateand identify protein librarymembers based on their catalytic or target molecule-bindingproperties.</p><p>In a first study, phage display libraries of the lipolyticenzyme Lipolase from Thermomyces lanuginosa were constructed,the objective being to identify variants with improvedcatalytic efficiency in the presence of detergents. Toconstruct the libraries, nine positions were targeted for codonrandomization, all of which are thought to be involved in theconformational change-dependent enzyme activation that occursat water-lipid interfaces. The aim was to introduce two tothree amino acid mutations at these positions per lipase gene.After confirming that the wt enzyme could be functionallydisplayed on phage, selections with the library were performedutilizing a mechanism-based biotinylated inhibitor in thepresence of a detergent formulation. According to rhodamineB-based activity assays, the fraction of active clonesincreased from 0.2 to 90 % over three rounds of selection.Although none of the variants selected using this approachshowed increased activity, in either the presence or absence ofdetergent compared to the wild type enzyme, the resultsdemonstrated the possibility of selecting variants of theenzyme based on catalytic activity.</p><p>In the following work, phage libraries of the StaphylococcalProtein A (SPA)-derived Z-domain, constructed by randomizationof 13 surface-located positions, were used to isolate Z domainvariants (affibodies) with novel binding specificities. Astargets for selections, the parental SPA domains as well as twopreviously selected affibodies directed against two unrelatedtarget proteins were used. Binders of all three targets wereisolated with affinities (KD) in the range of 2-0.5 µM.One SPA binding affibody (Z_SPA-1) was shown to bind to each of the fivehomologous native IgG-binding domains of SPA, as well as theZdomain used as the scaffold for library constructions.Furthermore, the Z_SPA-1affibody was shown to compete with one of thenative domains of SPA for binding to the Fc part of humanantibodies, suggesting that the Z_SPA-1affibody bound to the Fc-binding surface ofthe Z domain. The majority of the affibodies isolated in theother two selections using two different affibodies as targets,showed very little or no binding to unrelated affibodies,indicating that the binding was directed to the randomizedsurface of their respective targets, analogously toanti-idiotypic antibodies.</p><p>The structure of the wild type Z domain/Z_SPA-1affibody co-complex was determined by x-raycrystallography, which confirmed the earlier findings in thatthe affibody Z_SPA-1affibody was shown to bind to the Fc bindingsurface of the Z domain. Further, both the Z domain and the Z_SPA-1affibody had very similar three helix-bundletopologies, and the interaction surface involved ten out of thethirteen randomized residues, with a central hydrophobic patchsurrounded by polar residues. In addition, the interactionsurface showed a surprisingly high shape complementarity, giventhe limited size of the library used for selections. The Z_SPA-1affibody was further investigated for use invarious biotechnological applications. In one study, the Z_SPA-1affibody was successfully recruited as a novelaffinity gene fusion partner for production, purification anddetection of cDNA-encoded recombinant proteins using anSPA-based medium for affinity chromatography. Further, the SPAbinding capability of the Z_SPA-1affibody was employed for site-specific andreversible docking of Z_SPA-1affibody-tagged reporter proteins onto an SPAfusion protein anchored to a cellulose surface via acellulose-binding moiety. These generated protein complexesresembles the architecture of so-called cellulosomes observedin cellulolytic bacteria. The results suggest it may bepossible to use anti-idiotypic affibody-binding protein pairsas modules to build other self-assembling types of proteinnetworks.</p><p><b>Keywords:</b>phage display, selection, mechanism-basedinhibitor, affinity domains, crystal structure, Staphylococcusaureus protein A, affinity chromatography, anti-idiotypicbinding pairs, affibody, combinatorial, protein engineering,lipase, cellulosome, assembly.</p>

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 132-138).