Li Cho Hao (1913-1987)

Chinese-born US 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 Guangzhu and educated at the University of Nanjing. In 1935 he emigrated to the USA, where he took up postgraduate studies at the University of California at Berkeley and later joined the staff. He became professor 1950.

Li spent his entire academic career studying the pituitary-gland hormones. In collaboration with various co-workers, he isolated several protein hormones, including adreno-corticotrophic 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.