Gordon Guroff, 66, a noted biochemist and neurobiologist who was deputy scientific director of the National Institute of Child Health and Human Development at the National Institutes of Health, was killed July 9 in a traffic accident in Moultonboro, N.H.

New Hampshire State Police said Dr. Guroff, a resident of Rockville, was a passenger in a car driven by his brother, Gregory Guroff of Chevy Chase, when the vehicle ran out of control and turned over. Dr. Guroff was pronounced dead at the scene. He was vacationing at Lake Winnipesaukee, N.H.

Dr. Guroff joined what is now NIH's National Heart, Blood and Lung Institute in 1959. He did pioneering research on hydroxylation, the molecular mechanism through which certain amino acids become the neurotransmitters serotonin, norepinephrine and dopamine.

Neurotransmitters are the means by which one cell in the brain talks to another, and Dr. Guroff's work filled in an important gap in knowledge of how the process works. The mechanism of hydroxylation became known as the "NIH shift."

Dr. Guroff also was credited with discovering a new class of proteases that are activated by calcium and with making important contributions to a new method, called affinity chromatography, of purifying proteins.

In 1968, Dr. Guroff transferred to the Laboratory of Biomedical Sciences of the National Institute of Child Health and Human Development. His subsequent projects included studies of nerve growth factor and related growth factors that are responsible for much of the development of the human nervous system. These factors are now emerging as potential therapies for neurodegenerative diseases and injuries to the brain.

In 1982, Dr. Guroff was named deputy scientific director of the national child health institute.

Dr. Guroff was born in Chicago. He graduated from the University of Illinois in 1954 and received a master's degree in biochemistry at Auburn University in 1956. He received his doctorate in biochemistry at the University of Wisconsin in 1959.

In the course of his career, Dr. Guroff trained more than 100 postdoctoral fellows from around the world in his program at NIH, and he was a professorial lecturer in biochemistry at George Washington University.

He was the author of Molecular Neurobiology, a textbook, and he published nearly 200 papers in professional journals. He was the editor of three volumes in a series on growth and maturation factors and the editor of another series on oncogenes, genes and growth factors. He was a member of the editorial advisory boards of a number of professional journals.

His marriage to Julie Guroff ended in divorce.

In addition to Gregory Guroff, Dr. Guroff's survivors include his wife of 26 years, Marjorie Robert-Guroff, and their two children, Sarah and Robert Guroff, all of Rockville; three children from his first marriage, Peter Guroff of Pittsburgh, Margaret Guroff of Baltimore and Stephen Guroff of San Diego; his mother, Sarah Guroff of Rockville; another brother, Avram "Buzz" Guroff of McLean; and four grandchildren.