Tricking an Enzyme Into Making Better Insulin

Mary Boyajian, a junior majoring in chemical engineering at Caltech, spent her summer as a student in the Summer Undergraduate Research Fellowships (SURF) program trying to trick an enzyme. The enzyme, tRNA synthetase, has a very specific chemical target, and Boyajian wanted the enzyme to ease up a bit on its requirements so that it might also find acceptable a slightly altered version of the target. The work might sound esoteric, but it was Boyajian's piece of a project with an end goal that could benefit millions: devising a faster-acting insulin-replacement therapy for the treatment of diabetes.

A normally functioning pancreas keeps blood sugar within a narrow range by releasing large bursts of the hormone insulin after meals. Insulin helps cells absorb excess glucose and prevents the liver from producing additional sugar. In the case of diabetics, however, either the cells become resistant to the effects of insulin or the body simply cannot produce enough of the hormone, so additional insulin is needed.

In the 1920s, insulin isolated from animals became the first insulin-replacement therapy for diabetics. Forty years later, scientists figured out how to make human insulin in the lab. However, that synthetic insulin behaves a bit differently in the body. For example, it tends to clump up and therefore takes a long time for the body to absorb.

To improve the speed or ease of absorption, chemists have designed replacement therapies that are analogs of human insulin, made by substituting some of insulin's building blocks, or amino acids, with other naturally occurring amino acids. However, there is room for improvement. For example, scientists would like to make therapies that kick in faster, last longer, and offer a longer shelf life.

In all current insulin-replacement therapies, certain naturally occurring amino acids are swapped for other naturally occurring amino acids. But in the lab of David Tirrell, the Ross McCollum–William H. Corcoran Professor and professor of chemistry and chemical engineering at Caltech, chemists are working with what are known as noncanonical amino acids. These variants are designed and made in the lab to have slightly altered chemical structures. If expressed in a protein, these synthetic amino acids can introduce entirely new functions or capabilities. Tirrell's group has the idea to swap out a naturally occurring amino acid from insulin with a noncanonical amino acid to create a replacement therapy that would outperform those on the market today.

Boyajian's role this summer was to introduce specific mutations in the enzyme tRNA synthetase. Each of the 20 amino acids that are expressed naturally in proteins has its own tRNA synthetase that hunts within cells for its specific amino acid target, so that the amino acid can be incorporated in the right sequence to make proteins. Even a small difference in an amino acid's structure will deter its tRNA synthetase.

"When I started this project, I had no idea that changing one amino acid could change so much about a protein, but it can," says Boyajian. "My job is to mutate the tRNA synthetase so that it won't see a modified amino acid—one of our noncanonical amino acids—and say, 'That's the wrong one. Take it out.'"

To get an idea of how she might mutate the enzyme, Boyajian studied the known structures of similar tRNA synthetases and how they interact with their target molecules.

Once she had an idea for a mutation, she introduced the changes into the gene that codes for the tRNA synthetase. Then she used a standard technique in molecular biology called polymerase chain reaction (PCR) to make many copies of it. Next she grew cells with the mutated enzymes on media lacking the naturally occurring amino acid—think of it as a type of food for cells. Once the cells ate up any small traces of the amino acid in the media, she fed them one of the noncanonical amino acids. If a mutated enzyme worked, it was able to "eat" the new amino acids; if not, the cells eventually died.

At the end of the summer, one of Boyajian's mutated tRNA synthetases showed promising results in terms of incorporating one of the noncanonical amino acids, and she is now working to scale-up the size of cultures to determine whether the new enzyme can be used to produce proteins for future experiments. In the long term, if the enzyme is found to efficiently incorporate a specific noncanonical amino acid, the Tirrell lab would use the enzyme to produce novel insulins that could be assessed as potential biopharmaceuticals to improve the quality of life for patients.

Boyajian, who also plays basketball and serves as one of the captains of the water polo team, says she learned a lot from her SURF experience. "My grad student mentors, Seth Lieblich and Kat Fang, were great, and everybody in the lab was very welcoming," she says. "It's really nice to see everything you learned in the classroom being applied."

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Kimm Fesenmaier
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SURF: Working to Make a Better Insulin
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Junior Mary Boyajian spent her summer working on a project that aims to devise a faster-acting insulin-replacement therapy for the treatment of diabetes.

Three's Not a Crowd

The public high school in Blue Springs, Missouri, just outside Kansas City, graduates more than 500 seniors each year. Remarkably, the valedictorian in 2015 was the younger sister of the valedictorian in 2014—who was the younger sister of the valedictorian in 2013.

And all three are now Caltech undergraduates.

These are the Butkovich sisters: junior Slava and sophomore Nina, both majoring in chemical engineering, and freshman Lazarina ("Laza"), currently deciding between chemical engineering and chemistry.

"In the nearly half-century since Caltech began admitting women to its undergraduate program, 2015 is almost certainly the first year we've had three sisters enrolled in three different graduating classes at the same time," notes Barbara Green, interim dean of undergraduate students." The sisters represent "a three-peat," says Caltech admissions director Jarrid Whitney, not a package deal. "All our applicants are reviewed independently and without regard to siblings, parents, or other legacies. For three family members to receive consecutive offers of admission indicates how tremendously talented all three of them must be."

For their part, Slava, Nina, and Laza find their own nearly identical trajectories unsurprising. "We were taught at a young age that science majors can do a lot of good for society," Slava explains. "Anyway," adds Nina, "science is more objective than other things, like English and law. It has right answers."

Instead, they give much of the credit for nurturing their talents to their father, who is a lawyer, and their mother, a chemical engineer. They also single out recently retired Blue Springs High chemistry teacher Evan Manuel. "He's the above-and-beyond teacher," says Nina. "His passion for the sciences inspires his students."

Manuel praises the sisters for having "high expectations—not just of themselves but of others around them. I'm sure it's because of how they were brought up. And they've generously shared that perspective with their peers."

For example, the three young women, whose own heritage is Slavic and Filipino, cofounded their school's Association for Cultural and Ethnic Diversity and hosted its monthly world culture celebrations. That willingness to serve, says Manuel, earned them the respect of their peers. "And it's not a far-removed, no-interaction, pedestal kind of respect," he adds. "They like helping people, so people like them. Their college recommendation letters were some of the easiest I've ever been asked to write."

Even before landing in Pasadena, they had already completed summer research projects in university chemistry labs: Slava at Baylor and Missouri S&T, her sisters at the University of Iowa. They also tutored classmates in a variety of subjects in between sitting for a combined total of almost four dozen AP exams, many in subjects not even offered by their school.

At Caltech, all three Butkoviches will be pursuing summer research opportunities. Slava, who is planning a career in anti-cancer research, was named a Howard Hughes Medical Institute Summer Undergraduate Research Fellowships (SURF) fellow last year. They are active in the undergraduate house system (Nina is a member of Ruddock House; Laza and Slava are members of Dabney) and have taken part in yoga, tennis, tai chi, karate, and the NERF club. Their course loads are challenging, but none are carrying an overload. "I don't think extreme units is smart," Nina says.

In fact, according to all three, one of the biggest challenges since leaving high school has been learning to rely on something they had honestly never needed before now: study groups.

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The Butkovich sisters—junior Slava, sophomore Nina, and freshman Lazarina—find their own nearly identical trajectories unsurprising.

When Harry Met Arnold

A Milestone in Chemistry

On November 12 and 13, the Beckman Institute at Caltech hosted a symposium on "The Shared Legacy of Arnold Beckman and Harry Gray." The two began a close working relationship in the late 1960s, when Gray arrived at Caltech. In this interview, Gray provides some background.

How did you come to Caltech?

I grew up in southern Kentucky. I got my BS in chemistry in 1957, and my professors told me to go to grad school at Northwestern University in Evanston, Illinois, to continue my studies in synthetic organic chemistry. They didn't give me a choice. Western Kentucky College had physical chemistry, analytical chemistry, organic chemistry, and that was it.

When I got to Northwestern I met Fred Basolo, who became my mentor. He did inorganic chemistry, which I was very surprised to discover even existed as a research field. I was so excited by his work, which was studying the mechanisms of inorganic reactions, that I decided to switch fields and do what he did. I got my PhD in 1960 from work on the syntheses and reaction mechanisms of platinum, rhodium, palladium, and nickel complexes. A complex has a metal atom sitting in the middle of as many as six ions or molecules called ligands. The metal has empty orbitals that it wants to fill with paired-up electrons, and the ligands have electron pairs they aren't using, so the metal and its ligands form stable bonds.

I had gotten into chemistry in the first place because I'd always been interested in colors. Even when I was a little kid, colors fascinated me. I really wanted to understand them, and many complexes have brilliant, beautiful colors. At Northwestern I heard about crystal-field theory, which was the first attempt to explain how metal complexes got their colors. All the crystal-field theory's big shots were in Copenhagen, so I decided to go there as a postdoc. Which I did.

I soon found out that crystal-field theory didn't go far enough. It only explained the colors of a limited set of metal ions in solution, and it couldn't explain charge transfers and a lot of other things. All the atoms were treated as point charges, with no provision for the bonds between the metal and the ligands. There weren't any bonds. So I helped develop a new theory, called ligand-field theory, which put the bonds back in the complexes. Carl Ballhausen, a professor at the University of Copenhagen, and I wrote a paper on a "metal-oxo" complex in which an oxygen atom was triple-bonded to a vanadium ion. The triple bond in our theory was required to account for the blue color of the vanadium-oxo complex. We also could explain charge transfers in other oxo complexes. Bonds were back in metal complexes!

Metal-oxo bonds are very important in biology. They are crucial in a lot of reactions, such as the oxygen-producing side of photosynthesis; the metabolism of drugs by cytochrome P-450, which often leads to toxic interactions with other drugs; and respiration. When we breathe in O2, our respiratory system splits the O=O bond, forming a metal-oxo complex as a reactive intermediate on the way to the product, which is water.

My work on bonding in metal oxo complexes got me a job as an assistant professor at Columbia University in 1961. By '65 I was a full professor and getting offers from many places, including Caltech. I loved Columbia, and I would have stayed there, but the chemistry department was very small. I knew it would be hard to build inorganic chemistry in a small department that concentrated on organic and physical chemistry.

There weren't any inorganic chemists at Caltech, either, but division chair Jack Roberts encouraged me to build the field up to five or six faculty members. I came to Caltech in 1966, and we now have a very strong inorganic chemistry group.

When I got here, I started work in two new areas at the interface of inorganic chemistry and biology. I'm best known for my work showing how electrons flow through proteins in respiration and photosynthesis. I won the Wolf Prize and the Welch Prize and the National Medal of Science for this work.

I also got into inorganic photochemistry—solar-energy research. That work started well before the first energy crisis in 1973, and continued until oil became cheap again in the early 1980s and solar-energy research was no longer supported. In the late '90s, I restarted the work. Now I'm leading an NSF Center for Chemical Innovation in Solar Fuels, which has an outreach activity I proudly call the Solar Army.

And how's that going?

The Solar Army keeps growing. We now have at least 60 brigades at high schools across the U.S., and 10 more abroad. I'd say that about 1,000 students have been through the program since 2008. We're getting young scientists involved in research that could have a profound effect on the world they're going to inherit. They're helping us look for light absorbers and catalysts to turn water into hydrogen fuel, using nothing but sunlight. The solar materials need to be sturdy metal oxides that are abundant and dirt cheap. But there are many metals in the periodic table. When you start combining them in twos and threes in varying amounts, there are literally millions of possibilities to be tested. We already have found several very good water oxidation and reduction catalysts, and since the National Science Foundation has just renewed our CCI Solar Fuels grant, we expect to make great progress in the coming years in understanding how they work.

Let's shift gears and talk about the Beckman Institute. How did you first meet Arnold Beckman [PhD '28, inventor of the pH meter, founder of Beckman Instruments, and a Life Trustee of Caltech]?

I gave a talk back in 1967, probably on Alumni Day. Arnold was the chair of Caltech's Board of Trustees at the time, and he and his wife, Mabel, were seated in the second row. When the talk was over, they came down and introduced themselves. Mabel said—and I remember this very well—she said, "Arnold, I didn't understand much of what this young man said, but I really liked the way he said it." Arnold gave me the thumbs up, and that started our relationship.

When I became chairman of the Division of Chemistry and Chemical Engineering in 1978, I asked him to be on my advisory committee. I didn't ask him for money, but I asked him for advice, and we became quite close. He said he wanted to do something for us. That led to his gift for the Arnold and Mabel Beckman Laboratory of Chemical Synthesis, as well as a gift for instrumentation.

He liked it that we raised money to match his instrument gift. He told me that he wanted to do something bigger, so we started thinking about building the Beckman Institute. [Caltech President] Murph Goldberger and I would go down to Orange County about every week with a new plan. He rejected the first four or five until we came up with the idea of developing technology to support chemistry and biology—methods and instruments for fundamental research—and creating resource centers to house them.

Once we agreed on what the building should house, we started planning the building itself. But when we showed Arnold our design, which was four stories plus a basement, he said, "That's not big enough. You need another floor for growth." So we added a subbasement that was quickly occupied by a resource center for magnetic-resonance imaging and optical imaging that has been heavily used by biologists, chemists, and other investigators.

The Beckman Institute has done a lot over the last 25 years. But it develops technology for general research use, so it doesn't often make the headlines itself. Are you OK with that?

Many advances in science and technology have been made in the Beckman Institute over the last 25 years. The methods and instruments that have been developed in BI resource centers have made enormous impacts at the frontiers of chemistry and biology. Solar-fuels science and human biology are just two examples of areas where work in the Beckman Institute has made a big difference. And there are many more. Am I proud? You bet I am!

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Douglas Smith
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When Harry Met Arnold
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When Harry Met Arnold
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Caltech celebrates the 25th year of the Beckman Institute and the 80th birthday of Harry Gray, the Beckman Professor of Chemistry and the founding director of the institute.
Monday, November 30, 2015

Microbial diners, drive-ins, and dives: deep-sea edition

Elachi to Retire as JPL Director

Charles Elachi (MS '69, PhD '71) has announced his intention to retire as director of the Jet Propulsion Laboratory on June 30, 2016, and move to campus as professor emeritus. A national search is underway to identify his successor.

"A frequently consulted national and international expert on space science, Charles is known for his broad expertise, boundless energy, conceptual acuity, and deep devotion to JPL, campus, and NASA," said Caltech president Thomas F. Rosenbaum in a statement to the Caltech community. "Over the course of his 45-year career at JPL, Charles has tirelessly pursued new opportunities, enhanced the Laboratory, and demonstrated expert and nimble leadership. Under Charles' leadership over the last 15 years, JPL has become a prized performer in the NASA system and is widely regarded as a model for conceiving and implementing robotic space science missions."

With Elachi at JPL's helm, an array of missions has provided new understanding of our planet, our moon, our sun, our solar system, and the larger universe. The GRAIL mission mapped the moon's gravity; the Genesis space probe returned to Earth samples of the solar wind; Deep Impact intentionally collided with a comet; Dawn pioneered the use of ion propulsion to visit the asteroids Ceres and Vesta; and Voyager became the first human-made object to reach interstellar space. A suite of missions to Mars, from orbiters to the rovers Spirit, Opportunity, and Curiosity, has provided exquisite detail of the red planet; Cassini continues its exploration of Saturn and its moons; and the Juno spacecraft, en route to a July 2016 rendezvous, promises to provide new insights about Jupiter. Missions such as the Galaxy Evolution Explorer, the Spitzer Space Telescope, Kepler, WISE, and NuSTAR have revolutionized our understanding of our place in the universe.

Future JPL missions developed under Elachi's guidance include Mars 2020, Europa Clipper, the Asteroid Redirect Mission, Jason 3, Aquarius, OCO-2, SWOT, and NISAR.

Elachi joined JPL in 1970 as a student intern and was appointed director and Caltech vice president in 2001. During his more than four decades at JPL, he led a team that pioneered the use of space-based radar imaging of the Earth and the planets, served as principal investigator on a number of NASA-sponsored studies and flight projects, authored more than 230 publications in the fields of active microwave remote sensing and electromagnetic theory, received several patents, and became the director for space and earth science missions and instruments. At Caltech, he taught a course on the physics of remote sensing for nearly 20 years

Born in Lebanon, Elachi received his B.Sc. ('68) in physics from University of Grenoble, France and the Dipl. Ing. ('68) in engineering from the Polytechnic Institute, Grenoble. In addition to his MS and PhD degrees in electrical science from Caltech, he also holds an MBA from the University of Southern California and a master's degree in geology from UCLA.

Elachi was elected to the National Academy of Engineering in 1989 and is the recipient of numerous other awards including an honorary doctorate from the American University of Beirut (2013), the National Academy of Engineering Arthur M. Bueche Award (2011), the Chevalier de la Légion d'Honneur from the French Republic (2011), the American Institute of Aeronautics and Astronautics Carl Sagan Award (2011), the Royal Society of London Massey Award (2006), the Lebanon Order of Cedars (2006 and 2012), the International von Kármán Wings Award (2007), the American Astronautical Society Space Flight Award (2005), the NASA Outstanding Leadership Medal (2004, 2002, 1994), and the NASA Distinguished Service Medal (1999).

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He will move to campus as professor emeritus. A national search is underway to identify his successor.

Peters Named New Director of Resnick Sustainability Institute

Jonas C. Peters, the Bren Professor of Chemistry, has been appointed director of the Resnick Sustainability Institute. Launched in 2009 with an investment from philanthropists Stewart and Lynda Resnick and located in the Jorgenson Laboratory on the Caltech campus, the Resnick Institute concentrates on transformational breakthroughs that will contribute to the planet's sustainability over the long term.

The Resnick Sustainability Institute, which involves both the Chemistry and Chemical Engineering and Engineering and Applied Science divisions, serves as a prime example of the multidisciplinary approach prized by Caltech.

"Some of the most important challenges in sustainability are also among the most complex," says Peters, who has been a member of the Caltech faculty since 1999. "We are committed to working on problems that are uniquely suited to the Caltech environment. This means starting with fundamentals and leveraging the cross-catalysis of ideas and creativity of this campus to come up with ways to have substantial impact."

Because the world's natural resources are dwindling, Peters wants to continue focusing the Resnick Institute's efforts on efficient energy generation, storage, and use. Some current projects include development of advanced photovoltaics, photoelectrochemical solar fuels and cellulosic biofuels; energy conversion work on batteries and fuel cells; and efficiency in industrial catalysis and advanced research on electrical grid control and distribution.

In addition, the Resnick Institute is exploring new opportunities in the area of water sustainability. In September, the institute hosted a workshop entitled "Water Resilience and Sustainability: Can We Make LA Water Self-Sufficient?" The workshop examined the long-term potential for sustainable water use in urban environments, using the Los Angeles area as a case study.

"The Resnick Sustainability Institute is continuing to build one of the great centers for sustainability research," says Peters. "We are doing this by supporting the most talented young scientists and engineers committed to tackling the fascinating, critical, and yet very difficult challenges of this field."

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Jonas C. Peters has been appointed director of the Resnick Sustainability Institute.
Friday, October 30, 2015
Beckman Institute Auditorium – Beckman Institute

Teaching Statement Workshop

Wednesday, November 11, 2015
Center for Student Services 360 (Workshop Space) – Center for Student Services

Communication Strategies for Tutoring and Office Hours

Friday, October 23, 2015
Winnett Lounge – Winnett Student Center

TeachWeek Caltech Capstone Panel

Friday, October 16, 2015
Center for Student Services 360 (Workshop Space) – Center for Student Services

Course Ombudsperson Training, Fall 2015

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