Biophysical Society Bulletin | September 2025

In Memoriam

Sunney Chan

Sunney Chan (1936–2025), the California Institute of Technology’s George Grant Hoag Professor of Biophysical Chemistry, Emeritus, and long-time Biophysical Society member, died on May 5, 2025. Chan was born in San Francisco to immigrant, working-class parents. He pursued an interest in math and science that was ignited by teach ers at a Jesuit school in Hong Kong

He served as vice president of Academia Sinica from 1999 to 2003. To honor him for his service there, Academia Sinica established a lecture in his name in 2003. Harry Gray , a friend and colleague since meeting Chan at Caltech more than 50 years ago, says of him, “I greatly enjoyed collaborations with [Sunney]…His work laid the foundation for understanding the coupling of electron flow with proton pumping that drives the synthesis of ATP, the energy currency of life. Importantly, the currently accepted mechanism of dioxygen reduction to water at the binuclear iron-copper site owes much to his pioneering work.” Chan is remembered as a generous, caring colleague, includ ing by fellow Caltech faculty member John E. Bercaw , who recalls that when he asked Chan if he could use a spectrom eter in his NMR facility, Chan showed immediate enthusiasm and assisted Bercaw’s research group, leading to an import ant research article and ultimately a major program for the group. Bercaw credits Chan with teaching him how to teach chemistry courses and mentoring him as a faculty member at Caltech. In 2009, Chan published a review article in the Annual Review of Biophysics in which he discussed the trajectory of his career and the evolution of his work. He wrote that he “learned much” from his many (more than 200 at the time) students, postdocs, and colleagues and that many of his colleagues at Caltech had been inspirational. Chan is survived by his sisters, Elizabeth Gong and Diane Chan ; son, Michael Chan ; daughter-in-law, Marianne Lee ; and grand sons, Peter Chan and Nicholas Chan . He will be missed by his many friends and colleagues.

and went on to become the first in his family to attend college and eventually earn his doctorate. He received his PhD from the University of California, Berkeley in 1961. Chan began his Caltech career as an assistant professor of chemical physics in 1963 and became a tenured member of the faculty in 1968. In 1992, he was named the George Grant Hoag Professor of Biophysical Chemistry. His research evolved from fundamental studies in chemical physics to the use of nuclear magnetic resonance (NMR) to investigate bio logical molecules, including the base stacking of nucleic acids, the dynamic structures of membranes, and the function of membrane proteins. Chan received a Guggenheim Fellowship in 1968 and was elected to the American Academy of Arts and Sciences in 2010. He was also a fellow of the American Physical Society. In 1988, he became a member of Academia Sinica, Taiwan’s national academy. Chan retired from Caltech in 1997 and received emeritus status from the Institute in 2002. During his time at Caltech, Chan also served as executive officer for chemistry from 1978 to 1980 and again from 1989 to 1994. Sunney Chan

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September 2025

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