His work focused on molecules on the surface of cells. As a young researcher, he found an error in the structure determined by other researchers of a major cell surface molecule, sialic acid, and presented scientific proof to back up his finding.
He was born in Brooklyn, N.Y. His father died when he was a boy and the family lived in poverty.
"He was a poor kid, the son of immigrants," said his son-in-law, Dr. Ronald Schnaar, a Johns Hopkins School of Medicine professor. "He was very bright in school and skipped grades and was often the youngest in his class. But he had a passion for knowledge."
He enrolled at the City College of New York and received a bachelor of science in chemistry, but also had minors in biology and physics.
"He was that kind of scientist," his son-in-law said. "He liked to integrate information."
He then did graduate work at the University of Wisconsin's biochemistry department and earned a master's degree before serving as a rifleman in the Army in Europe during World War II.
After his military service, he returned to the University of Wisconsin and completed his doctorate while studying with Karl Link, who discovered the anticoagulant warfarin, a coumarin derivative. As a doctoral student, Dr. Roseman tested the synthesis and metabolism of coumarin derivatives. In later life, he took the same drug to treat his heart condition.
In the 1950s, as a young researcher, Dr. Roseman earned the nickname Saul "Serendipity" Roseman. According to a biographical sketch, he was studying an enzyme that metabolizes sialic acid while he was an assistant professor at the University of Michigan. Two groups of scientists, including two Nobel laureates, had previously announced that they had determined the structure of sialic acid. During his research on enzymes, he found that there was a major error in the proposed structure. While looking for one thing, he found something else that was of great value to science.
"As a junior faculty member, he knew he had to nail down his proof and figure out why two Nobel laureates were wrong," his son-in-law said.
"As far as I'm concerned, serendipity is a major tool of scientific investigation, and many, many major discoveries in biology and medicine have come through it," Dr. Roseman said in remarks during a tribute to him in 2001. "Take the human brain, for example. We think there's about 100,000 different types of enzymatic reactions that take place in the human brain. When you start from scratch looking for something in that, the chances that you're going to find what you're looking for are pretty low."
The unexpected, he said at that time, is just nature's "way of telling researchers where to look for the really interesting and important stuff."
Dr. Roseman was brought to Hopkins as a professor in 1965. He served as chair of the biology department from 1969 to 1973 and from 1988 to 1990. He lectured in biochemistry to generations of Hopkins undergraduates. He also raised funds to help build Mudd Hall on the Homewood campus, where his lab remains. Although he formally retired and accepted the title emeritus this year, his laboratory continues his research to this day.
"Saul arrived at Johns Hopkins in 1965, and his time here as a biology professor was nothing short of prolific," said Katherine Newman, dean of the Hopkins Krieger School of Arts and Sciences. "Saul loved coming to the lab every day, and that enthusiasm inspired his students and his colleagues alike."
Dr. Roseman was married to Martha Ozrowitz, whom he met when they were children in Brooklyn. She is the former Hopkins dean of academic advising.
Dr. Roseman received numerous awards and honors, including his 1972 election to the National Academy of Sciences and an honorary medical degree from the University of Lund in Sweden.
Family members said Dr. Roseman adopted Baltimore enthusiastically. He had season tickets to the Colts, Orioles and later Ravens. He subscribed to the Baltimore Symphony Orchestra and kept a sloop at Middle River.
Details of a memorial ceremony at the Johns Hopkins University planned for the fall are incomplete. A funeral was held Tuesday at Sol Levinson and Bros.
In addition to his wife of nearly 70 years, survivors include a son, Mark Roseman of Columbia; two daughters, Dorinda Gershman of Cleveland Heights, Ohio, and Cynthia Schnaar of Owings Mills; seven grandchildren; and 11 great-grandchildren.