Abstract

OBITUARY: Oleg Borisovich Ptitsyn (July 18, 1929 - March 22, 1999)

A. V. Finkelstein

Oleg Borisovich Ptitsyn died suddenly on March 22, 1999. He was an outstanding scientist, one of the creators of modern polymer theory and of a new branch of science, protein physics.

Oleg Ptitsyn was born in 1929 in Leningrad (St. Petersburg). After school he entered the Physical Faculty of Leningrad University. Here Ptitsyn met M. V. Volkenstein, then young but an already known theorist, and Ptitsyn earned his university degree in polymer physics under Volkenstein's supervision. Thus began the creation of the rotational-isomeric theory of polymers and the long-standing cooperation between Ptitsyn and Volkenstein; their joint publications appeared during a span of almost 40 years.

After gaining his Ph.D. degree at the age of 25, Ptitsyn joined the Institute of High-Molecular-Weight Compounds of the Academy of Sciences of the USSR. Gradually he became the hub around which disciples gathered. His ideas then, as always, were enough for all. With time theoretical work was augmented with experimental work. His own laboratory appeared. Ptitsyn created the rotational isomeric theory of polymers, highly acknowledged by the international scientific community, the theory of glassy transitions, and the first theory of coil-globule transitions. He presented lectures at many universities. He published (together with T. M. Birshtein) a fundamental monograph Conformations of Macromolecules. The book appeared in Russian and then in English. He was awarded a Doctor of Science degree in physics at the age of 34, and here his life sharply changed.

He became interested in biology and passed from chemical physics to molecular biology, from synthetic polymers to “living” macromolecules. Together with a group of adherents, he founded the Winter School on Molecular Biology, a school which brought up several generations of Russian molecular biologists. Together with A. S. Spirin, Ptitsyn founded the Institute of Protein Research of the Academy of Sciences of the USSR and moved from the northern capital to the small academic city of Pushchino on the Oka river. At this institute he headed the Laboratory of Protein Physics and became a scientific deputy director. At the same time he became Professor of the Moscow Physico-Technical Institute and began to create his course of lectures on protein physics.

In the seventies, Ptitsyn and his collaborators created a theory of protein and polypeptide secondary structure and started extensive experimental work on protein folding and physics of proteins and of model synthetic polypeptides.

The discovery of the “molten globule” (as it is now called in textbooks) takes a special place in the Ptitsyn's life. At first this globule, resembling the not yet hardened native protein, was deduced at “the point of the pen” in an attempt to understand how a protein can find its unique native spatial structure among the astronomical number of possible structures. The few next years was spent to find the molten globule as a special state of proteins, and, at the beginning of the eighties, it was found experimentally. Not only Ptitsyn's laboratory at the Institute of Protein Research participated in this work. Inspired by Ptitsyn, the molten globule was searched for, found, and studied by various methods by tens of scientists in different laboratories in many countries. The experimental results were quickly interpreted by theorists, and their questions targeted the experiments. At the end of the eighties the “molten globule” had found its way into textbooks, but Ptitsyn's interest in the molten globule, and especially in its role in the living cell and to the possibilities of application of this peculiar state of protein in medicine, did not fade to the last days of his life.

At the same time, he paid more and more attention to protein engineering. The artificial protein albebetin, de novo designed and then synthesized by him, was the first in Russia and one of the first in the World. Also, he widely used targeted mutation to create stable molten globules as well as to test his hypothesis on the leading role of super-conservative amino acid residues in the formation of “folding nuclei” of globular proteins. This work was done at the Institute of Protein Research, at the Scripps Institute, and at the National Institutes of Health (USA), where Ptitsyn spent a significant part of his time during his last years.

Ptitsyn was a member of the European Academy, a member of several Russian and international scientific councils, and an editor of many Russian and foreign journals. In his lifetime he saw protein science undergo many revolutions, and he contributed to most of them. He was the author of more than 260 scientific publications, wrote one book, and was preparing a second book when death overtook him.

Ptitsyn died on March 22 in England on the eve of a talk to be given at the University of Warwick. On July 18 we would have celebrated his 70th birthday.

A. V. Finkelstein