Straub was born in Nagyvrad (now Oradea in Romania) in 1914. He was educated at a Piarist grammar school and then at the Szeged University of Sciences in south-east Hungary. He carried out his initial research in the mid-1930s under Hungary's best-known biochemist, Albert Szent-Gyogyi, the recipient of the 1937 Nobel Prize for Medicine for his work in isolating ascorbic acid to produce vitamin C.
After a two-year stint on a Rockefeller scholarship at Cambridge, Straub returned to Szeged University in 1939 first as a research fellow and then as a member of the teaching staff. He concentrated his research on the production and structure of enzymes, the functioning of muscles and the synthesis of proteins.
His greatest scientific achievement came in 1941 with the discovery of how actin, which along with myosin proteins constitutes muscle fibres, controls muscle contraction. For this and his other scientific achievements he was twice in the 1950s awarded the Kossuth Prize, Hungary's highest award for intellectual achievement.
In the late 1940s Straub joined the Budapest University of Medicine. He became a prolific author in the 1950s, publishing several monographs and university textbooks. He also began a successful career as an administrator. From the 1960s onwards there were few institutes or committees in Hungary in the field of biochemistry that did not at some time come under his supervision.
He was an outstanding organiser. His pragmatism and his network of contacts in the Communist establishment helped him push through decisions that benefited many fellow-scientists in Hungary.
The greatest success of his lobbying endeavours was the establishment of the Szeged Biological Centre in 1970. It was a response to the revolution in biology following the discovery of DNA and under Straub, its founding director, the centre acquired international renown.
Unusually, Straub gave whole-hearted support to young researchers, valuing talent above reputation. And instead of transforming the centre into a lifelong sinecure, he left it in 1978 to become head of the less prestigious Enzymological Institute in Budapest.
But Straub continued at the top of Hungary's scientific hier-archy. He completed two stints as Vice-President of the Academy of Sciences and, thanks to his interest in the use of isotopes for biological research, became deputy chairman of the National Atomic Energy Committee.
Throughout, he remained 100 per cent loyal to the relatively benign Communist regime of Jnos Kdr, who ruled Hungary for over three decades after the crushing of the 1956 uprising. Straub was a leading member of the privileged intellectual establishment that had benefits showered on it by the authorities.
His position in that hierarchy was highlighted when he was elected a member of Hungary's rubber-stamp parliament in 1985 on an uncontested national list reserved for 35 prestigious candidates. The absurdity of the system was revealed when - along with leading Communist officials and the cream of Hungary's fellow-travelling intellectuals - Straub received over 99 per cent of the votes cast.
The predictability of his election to parliament could not have prepared anyone for the shock three years later when he was elected President of Hungary's collective head of state, the Presidential Council. That was in June 1988, a month after Kdr was ousted from the leading post of the Communist Party - known as the Hungarian Socialist Workers' Party (HSWP). The new leadership of the HSWP had embarked on a policy of radical reform which was to lead over the next two years to the dismantling of the Communist regime itself.
Straub was picked to become head of state in place of a hardline HSWP official, Kroly Nemeth, on the grounds that he was a non-Communist and a public figure with a nationwide reputation for his scientific achievements. In fact, he had always been loyal to the Communist regime, and he had even belonged to the HSWP's predecessor before 1956, in the darkest days of Stalinism.
But the elderly academician carried out his duties in a dignified way. He was present at a number of historic occasions. He welcomed George Bush to Hungary in June 1989 when the American President pledged for the first time financial aid to Hungary (and Poland) to help its transition to democracy and a market economy.
Straub stepped down as head of state in October 1989 when the Communist- era Presidential Council was abolished by a new transitional constitution.
After the multi-party elections of 1990 that ousted the reformed Communists from power, Straub, like other prominent public figures associated with the former regime, was pushed into the background. By then he had retired from his scientific posts, though for a while he visited the institutes where he had earlier worked, encouraging younger scientists.
Brun Straub was fond of quoting the Bible. Among his recurring biblical allusions was "Render unto Caesar the things which are Caesar's."
Brun Ferenc Straub, biochemist and head of state: born Nagyvrad, Hungary 5 January 1914; Director, Szeged Biological Centre 1970-78; Vice-President, Hungarian Academy of Sciences 1967-73, 1985-90; President of the Presidential Council, 1988-89; married 1940 Erzsebet Lichtneckert (died 1967), 1972 Gertrud Szabolcsi (died 1993; two daughters); died Budapest 15 February 1996.