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Sunney Chan, Caltech’s George Grant Hoag Professor of Biophysical Chemistry, Emeritus, passed away on May 5. He was 88 years of age.
Chan emerged from modest origins to become a distinguished biophysical chemist at Caltech and later in Taiwan. He expanded the frontiers of studying biological molecules employing a technique known as nuclear magnetic resonance (NMR). Chan was widely esteemed as an exceptional educator and mentor, actively engaged on campus in leadership roles within the Division of Chemistry and Chemical Engineering as well as in supporting Caltech students.
Indeed, throughout his tenure at Caltech, Chan received Caltech’s ASCIT (Associated Students of the California Institute of Technology) Teaching Award in 1991, the Richard M. Badger Teaching Prize in 1994, and held the position of Master of Student Houses from 1980 to 1983. Chan was appointed executive officer for chemistry twice (from 1978 to 1980 and again from 1989 to 1994), and he served as chair of the faculty from 1987 to 1989.
“Sunney exemplified the belief that teaching and research are interconnected, and that service is a vital aspect of the profession,” states Doug Rees, the Roscoe Gilkey Dickinson Professor of Chemistry and a Howard Hughes Medical Institute Investigator. “For those of us who followed his path as executive officers of chemistry, Sunney was the ideal model. He was an encouraging mentor and leaves behind a remarkable legacy of former students and postdocs, notable for the variety of their subsequent careers and passions.”
“Sunney Chan was a remarkable biophysical chemist who utilized magnetic resonance techniques to help unravel the structures and reactions of intricate membrane-bound metalloproteins,” comments Jacqueline Barton, Caltech’s John G. Kirkwood and Arthur A. Noyes Professor of Chemistry, Emerita. “However, Sunney’s importance to Caltech also stemmed from his service to the Caltech community, particularly focusing on undergraduate students.”
Chan was born in San Francisco on October 5, 1936, to immigrant parents who labored in a factory producing denim for Levi Strauss & Co. He spent his early years in what he referred to as a “Chinatown ghetto community.” “There was not a single drop of academic lineage in my family,” he remarked in the Annual Review of Biophysics in 2009. “I had no role models, scholars, scientists, or professionals to aspire to. I was the first in my family to go to university, earn a college degree, and obtain a PhD.”
At the age of 12, Chan’s parents sent him to middle school in Hong Kong, worried that he was growing up as a “‘hollow bamboo,’ lacking any awareness or appreciation of my Chinese heritage or culture,” Chan noted in the 2009 review article. Following his first term, he switched to an English-speaking school in Hong Kong run by Irish Jesuits. It was there that Chan developed an interest in mathematics and science, inspired by the exceptional teachers at the institution.
After graduating high school, Chan returned to the United States and enrolled at the University of San Francisco (USF), initially aiming to become a priest and science teacher. However, he quickly abandoned the idea of the Jesuit priesthood, and with guidance from faculty at USF, he transferred to UC Berkeley, where he earned his BS in chemical engineering in 1957 and his PhD in physical chemistry in 1961. His thesis focused on the molecular structure of oxetane (trimethylene oxide). Microwave data indicated a planar molecule, while far-infrared spectroscopy suggested a bent ring. Chan successfully reconciled these two different types of data.
At UC Berkeley, Chan intended to follow a career in industry, but his PhD supervisor urged him to apply for a postdoc at the laboratory of Harvard physicist Norman Ramsey. It was at Harvard that Chan began his work with NMR, a technique he would utilize throughout his career.
NMR is a non-invasive approach that takes advantage of the magnetic attributes of atomic nuclei to uncover valuable chemical details. When specific nuclei, like hydrogen or nitrogen, are subjected to a magnetic field, they absorb and re-emit electromagnetic radiation at distinct frequencies. These signals reveal insights into the local environment of nitrogen, carbon, and hydrogen atoms in molecules such as nucleic acids and proteins, thereby permitting scientists to deduce their structures and compositions in solution and under dynamic circumstances.
When Chan completed his postdoc in 1961, he was appointed as an assistant professor at UC Riverside. It was in this role, as Chan noted in 2009, that his “initial passion for science education was finally beginning to take form.” Eager to guide his students through scientific discovery, he gained access to an NMR spectrometer and led its operation within the department.
In 1961, Chan was also invited to deliver a lecture at Caltech. Within a week, the Institute offered him a position, which Chan initially declined. “As my research program was just starting to solidify, I did not think it was the right moment for me to make a transition,” Chan recounted. “I was also hesitant to relocate to such a high-powered institution.” However, after further contemplation, he opted for Caltech’s “stimulating research environment and excellent students.” This was a decision Chan never regretted, stating in 2009, “It is simply a prestigious institution. I have been affiliated with Caltech for over 45 years. Not for a moment have I ever regretted the choice I made in 1961.”
By the late 1960s, Chan began to shift his focus towards biophysics. “Considering that I … had no formal training in biochemistry or biology, I was entering the field with a disadvantage,” Chan reminisced. However, it turned out that his experience with spectroscopic tools and physics equipped him well for devising intriguing experiments on biological molecules, particularly centered on membranes and membrane proteins. He reported the pioneering use of high-resolution NMR to elucidate the stacking of nucleic acid bases in aqueous solution and analyzed the dynamics of lipids within membranes. From this exploration of membranes, Chan progressed to membrane proteins, conducting a series of biochemical and spectroscopic studies on the structures of metal ion sites in cytochrome oxidase, the terminal enzyme in the respiratory chain, along with investigations of blue copper electron transfer proteins.
“Sunney made significant contributions to biological inorganic chemistry,” remarks Harry Gray, the Arnold O. Beckman Professor of Chemistry at Caltech.
Chan later focused on the structure and mechanism of particulate methane monooxygenase, a complex copper-containing membrane protein, with the intention of creating a more effective catalyst for converting methane to methanol.
Chan was also an active and supportive colleague. Dennis Dougherty, the George Grant Hoag Professor of Chemistry, recalls the assistance Chan provided him early in his career, granting him unlimited access to a spectrometer in his laboratory. “That, combined with the intellectual guidance and support he provided, truly enabled me to launch my research program,” Dougherty comments. “Sunney was always a calming presence and a valued colleague for all of us in the Division of Chemistry and Chemical Engineering at Caltech.”
In 1997, Chan retired from Caltech and transitioned to academia…
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Sinica in Taiwan, where he established a research center focused on genomics and revamped the chemistry curriculum. Although primarily an administrator there—initially as director of the Institute of Chemistry and subsequently as vice president of the institute—Chan consistently engaged in his research on converting methane to methanol and comprehending protein folding in aqueous environments. He was awarded emeritus status by Caltech in 2002.
Throughout his professional journey, Chan garnered a multitude of accolades and recognitions, starting with a Guggenheim Fellowship in 1968. He became a member of the American Physical Society in 1987, the American Association for the Advancement of Science in 1992, the Academy of Sciences for the Developing World and the Biophysical Society in 2004, the American Academy of Arts and Sciences in 2010, and the International Academy of Physical Sciences in 2011. In 2004, Chan received the William C. Rose Award from the American Society for Biochemistry and Molecular Biology for “exceptional contributions to biochemical and molecular biological research and a proven dedication to the mentorship of younger scientists.” In 2021, he was honored with the Presidential Science Award in Taiwan.
To commemorate Chan for his contributions at Academia Sinica, a lecture series was created in his honor. The lecture website describes Chan as “particularly motivational to younger scientists, and his willingness to share insights on chemistry, scientific perspectives, life wisdom, and his expertise in wine, culinary arts, and fine dining is widely acknowledged within the community here.”
In 2009, Chan observed that he “gained significant knowledge” from his numerous (over 200 at that time) students, postdoctoral researchers, and collaborators. “Many of my former students and postdocs have ventured into groundbreaking science and even pioneered new research fields,” he mentioned. “I take pride in them. However, that is how it should be. Looking back, I believe my approach to student training has been effective. The most crucial aspect of scientific inquiry is posing questions, and I educated my students on how to formulate and ask these questions. Without questions—regardless of their quality—there is no challenge to address.”
Chan is survived by his spouse of 60 years, Irene; his sisters Elizabeth Gong and Diane Chan; son Michael Chan (who currently serves as a professor of life sciences at the Chinese University of Hong Kong); daughter-in-law Marianne Lee; and grandsons Peter Chan and Nicholas Chan.
A memorial viewing and symposium in honor of Chan were conducted in Taiwan. A service and burial took place in San Francisco. Furthermore, the Institute of Chemistry, Academia Sinica, plans to create a permanent website to pay tribute to Chan. Donations can be made here.