From UC Riverside (US): “Picosecond electron transfer in peptides can help energy technologies”

UC Riverside bloc

From UC Riverside (US)

April 13, 2021
Holly Ober
Senior Public Information Officer
(951) 827-5893
holly.ober@ucr.edu

Hydrogen bonds reshape peptides to move electrons a million times faster than previously known.

Biological energy flows, such as in photosynthesis and respiration, depend on the transfer of electrons from one molecule to another. Despite its importance to sustaining life, factors governing the rate of electron transfer, especially over long distances, are not well understood because the systems that mediate such ultrafast processes are very complex. A better understanding of electron transfer rates would help scientists improve chemical transformations, energy conversion, electronic devices, and photonic technologies.

Now, an international team of researchers led by UC Riverside has observed picosecond charge transfer mediated by hydrogen bonds in peptides. A picosecond is one trillionth of a second. As short-chain analogs of proteins, crucially important building blocks of living organisms, peptides are chains of chemically linked amino acids. The discovery shows the role of hydrogen bonds in electron transfer. The results are published in PNAS.

Valentine Vullev, a professor of bioengineering at UC Riverside’s Marlan and Rosemary Bourns College of Engineering, along with Daniel Gryko from the Polish Academy of Sciences (PL), and Harry Gray from the California Institute of Technology (US), led a team that discovered unusually ultrafast electron transfer from a donor to an acceptor molecule connected with oligopeptide linkers stretching up to 20 covalent bonds. Electron transfer usually takes a microsecond, or one millionth of a second, in peptides with such long through-bond distances.

The researchers were surprised to observe picosecond electron transfer- a rate 1 million times faster than previously known for such systems.

“It shouldn’t work, but it does,” Vullev said. “The picosecond charge transfer we observed contradicts structural biology, assuming the expected random distribution of structures of the flexible peptide chains.”

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The extended peptide (top) does not mediate charge transfer (detectable charge transfer)/ The folded peptide (bottom) mediates picosecond charge transfer along the hydrogen bonds between the donor and the acceptor (the hydrogen bonds are indicated with thin red dotted lines). Credit: Valentine Vullev.

The team chose donor and receptor molecules linked by short peptides they discovered actually assume well-defined structures stabilized by hydrogen bonds. Further analysis revealed that hydrogen bonds within each molecule brought the donor and acceptor close to each other in a scorpion-shaped molecular architecture, enabling picosecond electron transfer.

“This revolutionary design demonstrates short peptides can not only assume well-defined secondary conformations when templated by organic components but also provide a hydrogen-bonding network that can mediate electron transfer with unusually high efficiencies,” Vullev said. “Our work provides unprecedented paradigms for the design and development of charge-transfer pathways along flexible bridges, as well as insights into structural motifs for mediating electron transfer in proteins.”

The findings could lead to advances in energy storage as well as spur development of organic electronics that use conducting polymers instead of conducting minerals.

“One of the most exciting and fulfilling aspects about working in our group is being at the forefront of such discoveries and observing these spectacular results,” said co-author John Clark, a doctoral student in Vullev’s lab who did photochemical measurements for the research.

Other authors include Rafał Orłowski, Olga Staszewska-Krajewska, Hanna Jedrzejewska, and Agnieszka Szumna at the Polish Academy of Sciences; John A. Clark, James B. Derr, Eli M. Espinoza, and Maximilian F. Mayther at UC Riverside; and Jay R. Winkler at the California Institute of Technology.

See the full article here .

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UC Riverside Campus

The University of California, Riverside (US) is a public land-grant research university in Riverside, California. It is one of the 10 campuses of the University of California (US) system. The main campus sits on 1,900 acres (769 ha) in a suburban district of Riverside with a branch campus of 20 acres (8 ha) in Palm Desert. In 1907, the predecessor to UC Riverside was founded as the UC Citrus Experiment Station, Riverside which pioneered research in biological pest control and the use of growth regulators responsible for extending the citrus growing season in California from four to nine months. Some of the world’s most important research collections on citrus diversity and entomology, as well as science fiction and photography, are located at Riverside.

UC Riverside’s undergraduate College of Letters and Science opened in 1954. The Regents of the University of California declared UC Riverside a general campus of the system in 1959, and graduate students were admitted in 1961. To accommodate an enrollment of 21,000 students by 2015, more than $730 million has been invested in new construction projects since 1999. Preliminary accreditation of the UC Riverside School of Medicine was granted in October 2012 and the first class of 50 students was enrolled in August 2013. It is the first new research-based public medical school in 40 years.

UC Riverside is classified among “R1: Doctoral Universities – Very high research activity.” The 2019 U.S. News & World Report Best Colleges rankings places UC Riverside tied for 35th among top public universities and ranks 85th nationwide. Over 27 of UC Riverside’s academic programs, including the Graduate School of Education and the Bourns College of Engineering, are highly ranked nationally based on peer assessment, student selectivity, financial resources, and other factors. Washington Monthly ranked UC Riverside 2nd in the United States in terms of social mobility, research and community service, while U.S. News ranks UC Riverside as the fifth most ethnically diverse and, by the number of undergraduates receiving Pell Grants (42 percent), the 15th most economically diverse student body in the nation. Over 70% of all UC Riverside students graduate within six years without regard to economic disparity. UC Riverside’s extensive outreach and retention programs have contributed to its reputation as a “university of choice” for minority students. In 2005, UCR became the first public university campus in the nation to offer a gender-neutral housing option.UC Riverside’s sports teams are known as the Highlanders and play in the Big West Conference of the National Collegiate Athletic Association (NCAA) Division I. Their nickname was inspired by the high altitude of the campus, which lies on the foothills of Box Springs Mountain. The UC Riverside women’s basketball team won back-to-back Big West championships in 2006 and 2007. In 2007, the men’s baseball team won its first conference championship and advanced to the regionals for the second time since the university moved to Division I in 2001.

History

At the turn of the 20th century, Southern California was a major producer of citrus, the region’s primary agricultural export. The industry developed from the country’s first navel orange trees, planted in Riverside in 1873. Lobbied by the citrus industry, the UC Regents established the UC Citrus Experiment Station (CES) on February 14, 1907, on 23 acres (9 ha) of land on the east slope of Mount Rubidoux in Riverside. The station conducted experiments in fertilization, irrigation and crop improvement. In 1917, the station was moved to a larger site, 475 acres (192 ha) near Box Springs Mountain.

The 1944 passage of the GI Bill during World War II set in motion a rise in college enrollments that necessitated an expansion of the state university system in California. A local group of citrus growers and civic leaders, including many UC Berkeley(US) alumni, lobbied aggressively for a UC-administered liberal arts college next to the CES. State Senator Nelson S. Dilworth authored Senate Bill 512 (1949) which former Assemblyman Philip L. Boyd and Assemblyman John Babbage (both of Riverside) were instrumental in shepherding through the State Legislature. Governor Earl Warren signed the bill in 1949, allocating $2 million for initial campus construction.

Gordon S. Watkins, dean of the College of Letters and Science at University of California at Los Angeles(US), became the first provost of the new college at Riverside. Initially conceived of as a small college devoted to the liberal arts, he ordered the campus built for a maximum of 1,500 students and recruited many young junior faculty to fill teaching positions. He presided at its opening with 65 faculty and 127 students on February 14, 1954, remarking, “Never have so few been taught by so many.”

UC Riverside’s enrollment exceeded 1,000 students by the time Clark Kerr became president of the University of California(US) system in 1958. Anticipating a “tidal wave” in enrollment growth required by the baby boom generation, Kerr developed the California Master Plan for Higher Education and the Regents designated Riverside a general university campus in 1959. UC Riverside’s first chancellor, Herman Theodore Spieth, oversaw the beginnings of the school’s transition to a full university and its expansion to a capacity of 5,000 students. UC Riverside’s second chancellor, Ivan Hinderaker led the campus through the era of the free speech movement and kept student protests peaceful in Riverside. According to a 1998 interview with Hinderaker, the city of Riverside received negative press coverage for smog after the mayor asked Governor Ronald Reagan to declare the South Coast Air Basin a disaster area in 1971; subsequent student enrollment declined by up to 25% through 1979. Hinderaker’s development of innovative programs in business administration and biomedical sciences created incentive for enough students to enroll at Riverside to keep the campus open.

In the 1990s, the UC Riverside experienced a new surge of enrollment applications, now known as “Tidal Wave II”. The Regents targeted UC Riverside for an annual growth rate of 6.3%, the fastest in the UC system, and anticipated 19,900 students at UC Riverside by 2010. By 1995, African American, American Indian, and Latino student enrollments accounted for 30% of the UC Riverside student body, the highest proportion of any UC campus at the time. The 1997 implementation of Proposition 209—which banned the use of affirmative action by state agencies—reduced the ethnic diversity at the more selective UC campuses but further increased it at UC Riverside.

With UC Riverside scheduled for dramatic population growth, efforts have been made to increase its popular and academic recognition. The students voted for a fee increase to move UC Riverside athletics into NCAA Division I standing in 1998. In the 1990s, proposals were made to establish a law school, a medical school, and a school of public policy at UC Riverside, with the UC Riverside School of Medicine and the School of Public Policy becoming reality in 2012. In June 2006, UC Riverside received its largest gift, 15.5 million from two local couples, in trust towards building its medical school. The Regents formally approved UC Riverside’s medical school proposal in 2006. Upon its completion in 2013, it was the first new medical school built in California in 40 years.

Academics

As a campus of the University of California(US) system, UC Riverside is governed by a Board of Regents and administered by a president. The current president is Michael V. Drake, and the current chancellor of the university is Kim A. Wilcox. UC Riverside’s academic policies are set by its Academic Senate, a legislative body composed of all UC Riverside faculty members.

UC Riverside is organized into three academic colleges, two professional schools, and two graduate schools. UC Riverside’s liberal arts college, the College of Humanities, Arts and Social Sciences, was founded in 1954, and began accepting graduate students in 1960. The College of Natural and Agricultural Sciences, founded in 1960, incorporated the CES as part of the first research-oriented institution at UC Riverside; it eventually also incorporated the natural science departments formerly associated with the liberal arts college to form its present structure in 1974. UC Riverside’s newest academic unit, the Bourns College of Engineering, was founded in 1989. Comprising the professional schools are the Graduate School of Education, founded in 1968, and the UCR School of Business, founded in 1970. These units collectively provide 81 majors and 52 minors, 48 master’s degree programs, and 42 Doctor of Philosophy (PhD) programs. UC Riverside is the only UC campus to offer undergraduate degrees in creative writing and public policy and one of three UCs (along with Berkeley and Irvine) to offer an undergraduate degree in business administration. Through its Division of Biomedical Sciences, founded in 1974, UC Riverside offers the Thomas Haider medical degree program in collaboration with UCLA.[29] UC Riverside’s doctoral program in the emerging field of dance theory, founded in 1992, was the first program of its kind in the United States, and UC Riverside’s minor in lesbian, gay and bisexual studies, established in 1996, was the first undergraduate program of its kind in the UC system. A new BA program in bagpipes was inaugurated in 2007.

Research and economic impact

UC Riverside operated under a $727 million budget in fiscal year 2014–15. The state government provided $214 million, student fees accounted for $224 million and $100 million came from contracts and grants. Private support and other sources accounted for the remaining $189 million. Overall, monies spent at UC Riverside have an economic impact of nearly $1 billion in California. UC Riverside research expenditure in FY 2018 totaled $167.8 million. Total research expenditures at UC Riverside are significantly concentrated in agricultural science, accounting for 53% of total research expenditures spent by the university in 2002. Top research centers by expenditure, as measured in 2002, include the Agricultural Experiment Station; the Center for Environmental Research and Technology; the Center for Bibliographical Studies; the Air Pollution Research Center; and the Institute of Geophysics and Planetary Physics.

Throughout UC Riverside’s history, researchers have developed more than 40 new citrus varieties and invented new techniques to help the $960 million-a-year California citrus industry fight pests and diseases. In 1927, entomologists at the CES introduced two wasps from Australia as natural enemies of a major citrus pest, the citrophilus mealybug, saving growers in Orange County $1 million in annual losses. This event was pivotal in establishing biological control as a practical means of reducing pest populations. In 1963, plant physiologist Charles Coggins proved that application of gibberellic acid allows fruit to remain on citrus trees for extended periods. The ultimate result of his work, which continued through the 1980s, was the extension of the citrus-growing season in California from four to nine months. In 1980, UC Riverside released the Oroblanco grapefruit, its first patented citrus variety. Since then, the citrus breeding program has released other varieties such as the Melogold grapefruit, the Gold Nugget mandarin (or tangerine), and others that have yet to be given trademark names.

To assist entrepreneurs in developing new products, UC Riverside is a primary partner in the Riverside Regional Technology Park, which includes the City of Riverside and the County of Riverside. It also administers six reserves of the University of California Natural Reserve System. UC Riverside recently announced a partnership with China Agricultural University[中国农业大学](CN) to launch a new center in Beijing, which will study ways to respond to the country’s growing environmental issues. UC Riverside can also boast the birthplace of two name reactions in organic chemistry, the Castro-Stephens coupling and the Midland Alpine Borane Reduction..