In 20th-century biochemistry history of China, Szu-Chih Liu (刘思职, 1904—1983)(Fig. 1) acted as a central bridge in both academic genealogy and knowledge indigenization. Liu inherited the methodology and value established by Chinese earliest generation of biochemistry trailblazers, notably Hsien Wu, while fostered generations of biomedical students. He worked as a competent colleague of Professor Hsien Wu in the Department of Biochemistry at Peking Union Medical College (PUMC), elucidating the structural mechanism for protein denaturation and quantitatively examining antigen-antibody equilibrium in immunochemistry. He subsequently established the Department of Biochemistry at the College of Medicine, National Peking University, which was later reorganized into Beijing Medical College (now Peking University Health Science Center), where he led to explore a plethora of intriguing biochemical problems, as well as nurtured generations of talents. He initiated pioneering efforts to localize biochemistry in China through sustained efforts on unifying biochemistry terminology and developing biochemistry textbooks in the Chinese language, imperceptibly shaping the robust trajectory of biochemistry in China in the latter half of the 20th century. He was elected as an academician of the Division of Biology in the Chinese Academy of Sciences in 1957.
Szu-Chih Liu was born in 1904 in Xianyou, Fujian Province, China. After graduation from a public primary school, he studied at the Fuzhou Jiazhong Industrial School (福州甲种工业学校) . In 1921, Liu was admitted into the newly established Department of Chemistry at Amoy University (厦门大学). He transferred to the Great China University (大夏大学) in 1924, which later became a major part of East China Normal University, and obtained his bachelor's degree from the Great China University in 1925. He also acquired the Bachelor of Science degree at Southwestern University after studying there during 1925–1926. In 1926–1929, Liu pursued his Ph.D. at the University of Kansas majoring in physical chemistry, after which Liu returned to join the faculty of the Great China University.
In 1930, Liu moved to the PUMC as an associate in the Department of Biochemistry at PUMC, which stood as the paramount center of biochemistry in China under the leadership of Hsien Wu. From 1934 to 1935, Liu was a visiting scholar at the Kaiser Wilhelm Institute for Cell Physiology in Germany, and at the University of Cambridge in the United Kingdom. Liu was promoted to assistant professor of biochemistry in 1935 and associate professor in 1937. In 1942, the PUMC was forced into closure, and Liu transferred to the College of Medicine, National Peking University. In 1946, Liu was confirmed as the professor and founding dean of the Department of Biochemistry at the College of Medicine, National Peking University (Fig. 2). In 1952, the College of Medicine at Peking University was separated from Peking University and became Beijing Medical College, and Liu continued to work in the Department of Biochemistry at Beijing Medical College until his retirement in the early 1980s.
The first research focus of Szu-Chih Liu was to elucidate the molecular mechanism of protein denaturation. In PUMC, Hsien Wu, Szu-Chih Liu, and colleagues managed to resolve the mystery of denaturation and conducted a myriad of systematic biochemical analyses. In 1931, they comprehensively proposed the theory of protein denaturation for the first time that a soluble protein molecule was "not a flexible open chain of polypeptide but has a compact structure" held together by the "force of attraction between the polar groups in a single molecule," and "the compact and orderly structure" was disorganized in the process of denaturation.
The second field of study of Szu-Chih Liu was immunochemistry, where chemical equilibrium principles and quantitative analytical approaches were elegantly applied. In 1930s, they investigated the possibility and mechanism of antibody recovery and antigen recovery from antigen–antibody immune precipitate. Their quantitative characterization of the antigen-antibody stoichiometry in immune precipitate further underpinned the immunochemical equilibrium hypothesis.
In 1930s, Szu-Chih Liu investigated the biomedical application of ultrasonic radiation. In 1960s, Liu led his team to investigate ammonia toxicity, tolerance, metabolism, and clinical interventions. Liu and the famous historian of medicine T'ao Lee coauthored a detailed summary of biochemistry knowledge in ancient China (Fig. 3), and Liu also demonstrated profound enthusiasm in humanity, history and philosophy.
The courses of biochemistry, or originally physiological chemistry, had been taught in China since 1910s. However, biochemistry textbooks in early years were largely written in English. Moreover, at that time, most faculty members and students of biochemistry in China generally regarded English textbooks as more reliable, while expressing doubt and distrust toward Chinese translations. Even if biochemistry had been taught in China for decades, without terminology and textbooks in Chinese, the biochemistry discipline had never deeply rooted in China.
In the late 1940s, Liu enthusiastically organized biochemists to discuss the translation unification of biochemistry terminology in Chinese language, though their effort faced strong opposition. In the early 1950s, Liu again organized a team of patriotic biochemists in Beijing to translate and unify biochemistry terms. In July 1950, the Draft of Biochemistry Terminology was formulated as the first attempt at unifying Chinese terminology for biochemistry, and its revised edition Biochemistry Terminology was published in 1955 and used in all medical colleges in China.
The Biochemistry terminology by Liu laid the necessary foundation for biochemistry textbook compilation in Chinese, facilitating precise term choice and accurate translation. (Fig. 4) During 1951 to 1954, Liu led colleagues in the Department of Biochemistry at Beijing Medical College compiled the Outline of Biochemistry, one of the first comprehensive biochemistry textbook in Chinese language. Liu stated in its preface: "In order for science to take root in our homeland, it is essential to write textbooks in our own language. Biochemistry is no exception. This is the prime driving force behind the creation of this book."
In 1964, Liu's textbook was officially recommended by the Ministry of Health as the textbook for higher medical education in China, and the book title was changed from Outline of Biochemistry to Biochemistry, with enrichments and updates in contents, serving as the standard curriculum textbook from the 1960s through 1978, educating generations of biomedical students in China, while comprehensively formalizing the conceptual frame for biochemistry pedagogy in the second half of the 20th century China.
A concise and condensed version of biochemistry textbook was in urgent need for short-term medical training, thus an abridged textbook of the Biochemistry Lecture Notes was authored by Liu in 1951. The revised edition of this concise textbook, published in 1956, gained tremendous popularity.
Through his efforts in the standardization of biochemical terminology and the compilation of biochemistry textbooks in Chinese, Liu profoundly influenced the biochemistry development in China. Liu's indigenization contribution substantively shaped the development of biochemistry in China, fostering a brand new era of standardization, unification, and sinicization in biochemistry.
Professor Szu-Chih Liu not only dedicated to pioneering pursuit in his professional field, but also demonstrated a profound patriotic commitment. In 1949, he declined the airplane tickets that were offered to him, choosing instead to remain resolutely in China. He once said, "I firmly believed that my career lay in my homeland. My ultimate aspiration was to witness biochemistry take root in China and flourish. I was willing to dedicate all my efforts to this cause." Liu's lynchpin role to bridging the transmission of biochemistry knowledge across institutions and generations, along with his efforts for biochemistry to take root in China, will be honored. We commemorate Professor Liu by revisiting the insightful couplet he crafted which exhibited his poetic talent, offered a vividly depiction of science, and accurately encapsulated the regulation of metabolism.
"Life transforms, transformations bring about life; biochemistry is the process of transformation." （"生者化，化又生，生化即化生；"）
"New replaces old, and the old fades away; metabolism from new to old is continuation." （"新则陈，陈乃谢，新陈恒代谢。"）
Horizontal inscription: "Dynamic equilibrium."（"横批：动态平衡。"）
