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ContributorsShi, Ge (Performer) / ASU Library. Music Library (Publisher)
Created2018-03-25
ContributorsShatuho, Kristina (Performer) / ASU Library. Music Library (Publisher)
Created2018-03-27
Description
Photosystem I (PSI) is a multi-subunit, pigment-protein complex that catalyzes light-driven electron transfer (ET) in its bi-branched reaction center (RC). Recently it was suggested that the initial charge separation (CS) event can take place independently within each ec2/ec3 chlorophyll pair. In order to improve our understanding of this phenomenon, we have generated new mutations in the PsaA and PsaB subunits near the electron transfer cofactor 2 (ec2 chlorophyll). PsaA-Asn604 accepts a hydrogen bond from the water molecule that is the axial ligand of ec2B and the case is similar for PsaB-Asn591 and ec2A. The second set of targeted sites was PsaA-Ala684 and PsaB-Ala664, whose methyl groups are present near ec2A and ec2B, respectively. We generated a number of mutants by targeting the selected protein residues. These mutations were expected to alter the energetics of the primary charge separation event.
The PsaA-A684N mutants exhibited increased ET on the B-branch as compared to the A-branch in both in vivo and in vitro conditions. The transient electron paramagnetic resonance (EPR) spectroscopy revealed the formation of increased B-side radical pair (RP) at ambient and cryogenic temperatures. The ultrafast transient absorption spectroscopy and fluorescence decay measurement of the PsaA-A684N and PsaB-A664N showed a slight deceleration of energy trapping. Thus making mutations near ec2 on each branch resulted into modulation of the charge separation process. In the second set of mutants, where ec2 cofactor was target by substitution of PsaA-Asn604 or PsaB-Asn591 to other amino acids, a drop in energy trapping was observed. The quantum yield of CS decreases in Asn to Leu and His mutants on the respective branch. The P700 triplet state was not observed at room and cryogenic temperature for these mutants, nor was a rapid decay of P700+ in the nanosecond timescale, indicating that the mutations do not cause a blockage of electron transfer from the ec3 Chl. Time-resolved fluorescence results showed a decrease in the lifetime of the energy trapping. We interpret this decrease in lifetime as a new channel of excitation energy decay, in which the untrapped energy dissipates as heat through a fast internal conversion process. Thus, a variety of spectroscopic measurements of PSI with point mutations near the ec2 cofactor further support that the ec2 cofactor is involved in energy trapping process.
The PsaA-A684N mutants exhibited increased ET on the B-branch as compared to the A-branch in both in vivo and in vitro conditions. The transient electron paramagnetic resonance (EPR) spectroscopy revealed the formation of increased B-side radical pair (RP) at ambient and cryogenic temperatures. The ultrafast transient absorption spectroscopy and fluorescence decay measurement of the PsaA-A684N and PsaB-A664N showed a slight deceleration of energy trapping. Thus making mutations near ec2 on each branch resulted into modulation of the charge separation process. In the second set of mutants, where ec2 cofactor was target by substitution of PsaA-Asn604 or PsaB-Asn591 to other amino acids, a drop in energy trapping was observed. The quantum yield of CS decreases in Asn to Leu and His mutants on the respective branch. The P700 triplet state was not observed at room and cryogenic temperature for these mutants, nor was a rapid decay of P700+ in the nanosecond timescale, indicating that the mutations do not cause a blockage of electron transfer from the ec3 Chl. Time-resolved fluorescence results showed a decrease in the lifetime of the energy trapping. We interpret this decrease in lifetime as a new channel of excitation energy decay, in which the untrapped energy dissipates as heat through a fast internal conversion process. Thus, a variety of spectroscopic measurements of PSI with point mutations near the ec2 cofactor further support that the ec2 cofactor is involved in energy trapping process.
ContributorsBadshah, Syed Lal (Author) / Redding, Kevin E (Thesis advisor) / Fromme, Petra (Committee member) / Gould, Ian (Committee member) / Arizona State University (Publisher)
Created2014
Description
Photochromic molecules, which photoisomerize between two chemically and optically distinct states, are well suited for electron and energy transfer to covalently attached chromophores. This dissertation aims to manipulate electron and energy transfer by photochromic control in a number of organic molecular systems. Herein the synthesis, characterization and function of these organic molecular systems will be described. Electron and energy transfer were quantified by the use of steady state absorbance and fluorescence, as well as time-resolved fluorescence and transient absorbance. A dithienylethene-porphrin-fullerene triad was synthesized to investigate photochromic control of photo-induced electron transfer. Control of two distinct electron transfer pathways was achieved by photochromic switching. A molecular dyad was synthesized, in which fluorescence was modulated by energy transfer by photoinduced isomerization. Also described is a triplet-triplet annihilation upconversion system that covalently attaches fluorophores to improve quantum yield. Overall these studies demonstrate complex molecular switching systems, which may lead to advancement in organic electronic applications and organic based artificial photosynthesis systems.
ContributorsCrisman, Jeffrey (Author) / Gust, John D (Thesis advisor) / Rose, Seth (Committee member) / Moore, Ana (Committee member) / Arizona State University (Publisher)
Created2014
ContributorsCarlisi, Daniel (Performer) / ASU Library. Music Library (Publisher)
Created2018-04-07
Description
Yannis Constantinidis was the last of the handful of composers referred to collectively as the Greek National School. The members of this group strove to create a distinctive national style for Greece, founded upon a synthesis of Western compositional idioms with melodic, rhyhmic, and modal features of their local folk traditions. Constantinidis particularly looked to the folk melodies of his native Asia Minor and the nearby Dodecanese Islands. His musical output includes operettas, musical comedies, orchestral works, chamber and vocal music, and much piano music, all of which draws upon folk repertories for thematic material. The present essay examines how he incorporates this thematic material in his piano compositions, written between 1943 and 1971, with a special focus on the 22 Songs and Dances from the Dodecanese. In general, Constantinidis's pianistic style is expressed through miniature pieces in which the folk tunes are presented mostly intact, but embedded in accompaniment based in early twentieth-century modal harmony. Following the dictates of the founding members of the Greek National School, Manolis Kalomiris and Georgios Lambelet, the modal basis of his harmonic vocabulary is firmly rooted in the characteristics of the most common modes of Greek folk music. A close study of his 22 Songs and Dances from the Dodecanese not only offers a valuable insight into his harmonic imagination, but also demonstrates how he subtly adapts his source melodies. This work also reveals his care in creating a musical expression of the words of the original folk songs, even in purely instrumental compositon.
ContributorsSavvidou, Dina (Author) / Hamilton, Robert (Thesis advisor) / Little, Bliss (Committee member) / Meir, Baruch (Committee member) / Thompson, Janice M (Committee member) / Arizona State University (Publisher)
Created2011
Description
This paper describes six representative works by twentieth-century Chinese composers: Jian-Zhong Wang, Er-Yao Lin, Yi-Qiang Sun, Pei-Xun Chen, Ying-Hai Li, and Yi Chen, which are recorded by the author on the CD. The six pieces selected for the CD all exemplify traits of Nationalism, with or without Western influences. Of the six works on the CD, two are transcriptions of the Han Chinese folk-like songs, one is a composition in the style of the Uyghur folk music, two are transcriptions of traditional Chinese instrumental music dating back to the eighteenth century, and one is an original composition in a contemporary style using folk materials. Two of the composers, who studied in the United States, were strongly influenced by Western compositional style. The other four, who did not study abroad, retained traditional Chinese style in their compositions. The pianistic level of difficulty in these six pieces varies from intermediate to advanced level. This paper includes biographical information for the six composers, background information on the compositions, and a brief analysis of each work. The author was exposed to these six pieces growing up, always believing that they are beautiful and deserve to be appreciated. When the author came to the United States for her studies, she realized that Chinese compositions, including these six pieces, were not sufficiently known to her peers. This recording and paper are offered in the hopes of promoting a wider familiarity with Chinese music and culture.
ContributorsLuo, Yali, D.M.A (Author) / Hamilton, Robert (Thesis advisor) / Campbell, Andrew (Committee member) / Pagano, Caio (Committee member) / Cosand, Walter (Committee member) / Rogers, Rodney (Committee member) / Arizona State University (Publisher)
Created2012
Description
The purpose of this project was to examine the lives and solo piano works of four members of the early generation of female composers in Taiwan. These four women were born between 1950 and 1960, began to appear on the Taiwanese musical scene after 1980, and were still active as composers at the time of this study. They include Fan-Ling Su (b. 1955), Hwei-Lee Chang (b. 1956), Shyh-Ji Pan-Chew (b. 1957), and Kwang-I Ying (b. 1960). Detailed biographical information on the four composers is presented and discussed. In addition, the musical form and features of all solo piano works at all levels by the four composers are analyzed, and the musical characteristics of each composer's work are discussed. The biography of a fifth composer, Wei-Ho Dai (b. 1950), is also discussed but is placed in the Appendices because her piano music could not be located. This research paper is presented in six chapters: (1) Prologue; the life and music of (2) Fan-Ling Su, (3) Hwei-Lee Chang, (4) Shyh-Ji Pan-Chew, and (5) Kwang-I Ying; and (6) Conclusion. The Prologue provides an overview of the development of Western classical music in Taiwan, a review of extant literature on the selected composers and their music, and the development of piano music in Taiwan. The Conclusion is comprised of comparisons of the four composers' music, including their personal interests and preferences as exhibited in their music. For example, all of the composers have used atonality in their music. Two of the composers, Fan-Ling Su and Kwang-I Ying, openly apply Chinese elements in their piano works, while Hwei-Lee Chang tries to avoid direct use of the Chinese pentatonic scale. The piano works of Hwei-Lee Chang and Shyh-Ji Pan-Chew are chromatic and atonal, and show an economical usage of material. Biographical information on Wei-Ho Dai and an overview of Taiwanese history are presented in the Appendices.
ContributorsWang, Jinding (Author) / Pagano, Caio (Thesis advisor) / Campbell, Andrew (Committee member) / Humphreys, Jere T. (Committee member) / Meyer-Thompson, Janice (Committee member) / Norton, Kay (Committee member) / Arizona State University (Publisher)
Created2011
ContributorsShi, Zhan (Performer) / ASU Library. Music Library (Publisher)
Created2018-03-26
Description
The photosynthetic reaction center is a type of pigment-protein complex found widely in photosynthetic bacteria, algae and higher plants. Its function is to convert the energy of sunlight into a chemical form that can be used to support other life processes. The high efficiency and structural simplicity make the bacterial reaction center a paradigm for studying electron transfer in biomolecules. This thesis starts with a comparison of the primary electron transfer process in the reaction centers from the Rhodobacter shperoides bacterium and those from its thermophilic homolog, Chloroflexus aurantiacus. Different temperature dependences in the primary electron transfer were found in these two type of reaction centers. Analyses of the structural differences between these two proteins suggested that the excess surface charged amino acids as well as a larger solvent exposure area in the Chloroflexus aurantiacus reaction center could explain the different temperature depenence. The conclusion from this work is that the electrostatic interaction potentially has a major effect on the electron transfer. Inspired by these results, a single point mutant was designed for Rhodobacter shperoides reaction centers by placing an ionizable amino acid in the protein interior to perturb the dielectrics. The ionizable group in the mutation site largely deprotonated in the ground state judging from the cofactor absorption spectra as a function of pH. By contrast, a fast charge recombination assoicated with protein dielectric relaxation was observed in this mutant, suggesting the possibility that dynamic protonation/deprotonation may be taking place during the electron transfer. The fast protein dielectric relaxation occuring in this mutant complicates the electron transfer pathway and reduces the yield of electron transfer to QA. Considering the importance of the protein dielectric environment, efforts have been made in quantifying variations of the internal field during charge separation. An analysis protocol based on the Stark effect of reaction center cofactor spectra during charge separation has been developed to characterize the charge-separated radical field acting on probe chromophores. The field change, monitored by the dynamic Stark shift, correlates with, but is not identical to, the electron transfer kinetics. The dynamic Stark shift results have lead to a dynamic model for the time-dependent dielectric that is complementary to the static dielectric asymmetry observed in past steady state experiments. Taken together, the work in this thesis emphasizes the importance of protein electrostatics and its dielectric response to electron transfer.
ContributorsGuo, Zhi (Author) / Woodbury, Neal W (Thesis advisor) / Lindsay, Stuart M (Committee member) / Ross, Robert (Committee member) / Ozkan, Banu S (Committee member) / Moore, Thomas A. (Committee member) / Arizona State University (Publisher)
Created2012