The complete covalent structure of a novel boar DQH sperm surface protein resistant to many classical procedures of enzymatic fragmentation was determined. The relative molecular mass of the major form of this protein determined by ESI-MS and MALDI-MS was 13,065.2 ± 1.0 and 13,065.1, respectively. However, additional peaks differing by 162 Da (i.e., minus hexose), 365 Da (i.e., minus hexose and N-acetylhexosamine), 146 Da (i.e., plus deoxyhexose), and 291 Da (i.e., plus sialic acid) indicated the heterogeneity due to differences in glycosylation. The complete covalent structure of the protein was determined using automated Edman degradation, MALDI-MS, and post-source decay (PSD) MALDI-MS, and shown to consist of N-terminal O-glycosylated peptide followed by two fibronectin type II repeats. The carbohydrates are O-glycosidically linked to threonine 10, as confirmed by PSD MALDI-MS of the isolated N-terminal glycopeptide. Eight cysteine residues of the protein form four disulfide bridges, the positions of which were assigned from MALDI-MS and Edman degradation data. We conclude that mass spectral techniques provide an indispensable tool for the detailed analysis of the covalent structure of proteins, especially those that are refractory to standard approaches of protein chemistry.

Triad1 was recently identified as a nuclear RING finger protein, which is up-regulated during retinoic acid induced granulocytic differentiation of acute leukemia cells. Here we show that a cysteine-rich domain (C6HC), present in Triad1, is conserved in at least 24 proteins encoded by various eukaryotes. The C6HC consensus pattern C-x(4)-C-x(14–30)-C-x(1–4)-C-x(4)-C-x(2)-C-x(4)-H-x(4)-C defines this structure as the fourth family member of the zinc-binding RING, LIM, and LAP/PHD fingers. Strikingly, in 22 of 24 proteins the C6HC domain is flanked by two RING finger structures. We have termed the novel C6HC motif DRIL (double RING finger linked). The strong conservation of the larger tripartite TRIAD (two RING fingers and DRIL) structure indicates that the three subdomains are functionally linked and identifies a novel class of proteins.

Oleg Ptitsyn was a pioneer in protein folding studies: his discovery of molten globule folding intermediates revolutionized the field. He died in England on March 22, 1999, after a heart attack. Oleg Ptitsyn was born in St. Petersburg (Leningrad) on July 18, 1929, and took his M.Sc. in Molecular Physics at the University of Leningrad at the age of 22. He remained in Leningrad, at the Institute of High Molecular Compounds, first taking his Ph.D. in 1954 and then his D.Sc. in 1963 in physical and mathematical sciences. In 1967, he became Deputy Director of the Institute of Protein Research and simultaneously Head of the Laboratory of Protein Physics at Pushchino, at the Academy of Sciences Institute for Protein Research. He retained his position at Pushchino after becoming in 1992 a visiting member of the NIH Laboratory of Mathematical Biology, in the section of Robert Jernigan.

The hypothesis that life on earth evolved under thermophilic conditions and then adapted at cooler temperatures is based on the discovery, in the last decade, of organisms growing optimally at temperatures near and above 100 °C, termed “hyperthermophiles,” and on the rooted phylogenetic trees based on 16S rRNA sequences proposed by Woese and colleagues in which all branches leading to hyperthermophiles are short and located at the base of the tree. These observations led to the conclusion that the common ancestor of all extant organisms (cenancestor) was a hyperthermophile. This hypothesis, which implies the fascinating opportunity of studying the origin of life by investigating thermophilic organisms, is still the subject of controversy and debate. In particular, considerable opposition arose to the concept of the hyperthermophilic origin of life and to the interpretation of the phylogenetic and geological data. With this in mind, the collection of papers written by selected speakers from the international workshop Thermophiles: The keys to molecular evolution and the origin of life contributes significantly to the discussion by offering the opinions (some of them in open conflict) of leading protagonists from a range of disciplines. In fact, as the editors correctly point out, the majority of researchers in the thermophile field have backgrounds in biochemistry, microbiology, and genetics, but the views of geochemists, oceanographers, and evolutionists would also be of great interest. With this aim, the book gives an opportunity to readers with different backgrounds to approach such fundamental questions as to how life originated and under what environmental conditions.

Dr. Klein's name is misspelled in the print version of this article, on page 1010 in Volume 8, Number 5, 1999. The correct spelling is Teri E. Klein.