Choh Hao Li (sometimes Cho Hao Li) (; April 21, 1913 – November 28, 1987) was a Chinese-born American biochemist who discovered, in 1966, that human pituitary growth hormone (somatotropin) consists of a chain of 256 amino acids. In 1970 he succeeded in synthesizing this hormone, the largest protein molecule synthesized up to that time. Li was born in Guangzhou and educated at the Nanjing University. In 1935 he immigrated to the US, where he took up postgraduate studies at the University of California, Berkeley and later joined the staff. He became professor in 1950. He served as Director of the Hormone Research Laboratory at Berkeley from 1950 to 1967 and at UCSF from 1967 until his retirement in 1983. In 1955 he was elected as Academician of Academia Sinica, Republic of China. Li spent his entire academic career studying the pituitary-gland hormones. In collaboration with various co-workers, he isolated several protein hormones, including adrenocorticotropic hormone (ACTH), which stimulates the adrenal cortex to increase its secretion of corticoids. In 1956, Li and his group showed that ACTH consists of 39 amino acids arranged in a specific order, and that the whole chain of the natural hormone is not necessary for its action. He isolated another pituitary hormone called melanocyte-stimulating hormone (MSH) and found that not only does this hormone produce some effects similar to those produced by ACTH, but also that part of the amino acid chain of MSH is the same as that of ACTH. Scientific Achievements In 1940, Dr. Li successfully purified the luteinizing hormone from sheep pituitary glands. The whole process included grinding thousands of glands, extracting the hormone, and then identifying its chemistry and biology at the molecular level. This was a breakthrough in biological studies. Eight of the nine hormones secreted by the anterior pituitary were isolated and identified by Dr. Li and his research team. These nine hormones can be divided into three groups based on the similarity of their chemical properties and biological activities. The first group includes adrenocorticotropic hormone (ACTH), melanocyte-stimulating hormones (MSH), and lipotropin. 1953 - Dr. Li being the first person to isolate and extract ACTH. 1964 - Dr. Li and his research team discovered and isolated lipotropin, and its structure was defined in 1965. 1975 - Dr. Li discovered β-endorphin when they were trying to find β-lipotropin in camel brain. The team isolated human β-endorphin in 1976 and synthesized