We have studied nucleic acid double helix destabilization mediated by purified calf helix-unwinding proteins, measuring ultraviolet hyperchromicity to detect helix melting. Both,calf unwinding protein 1 (UPl) and a high salt eluting protein fraction are found to depress strongly the helix melting temperature (T,) of the synthetic alternating copolymers poly[d(AT) ] and poly[r(AU)], indicating t...

Mitochondrial aspartate aminotransferase is inactivated irreversibly on heating. The inactivated protein aggregates, but aggregation is prevented by the presence of the chaperonin 60 from Escherichia coli (GroEL). The chaperonin increases the rate of thermal inactivation in the temperature range 55-65 degrees C but not at lower temperatures. It has previously been shown [Twomey and Doonan (1997...

The targeting of tumor cells by peptides for drug delivery is a promising strategy for cancer therapy. Interleukin-2 (IL-2), which mediates anti-tumor cellular immune responses, has been approved as a therapy for cancer. However, the serious side effects and short half-life of recombinant IL-2 (rIL-2) has limited its use clinically. Somatostatin receptors (SSTRs), which are expressed in a large...

Thioredoxin, thioredoxin reductase and NADPH form the thioredoxin system and are the major cellular protein disulphide reductase. We report here that Escherichia coli thioredoxin and thioredoxin reductase interact with unfolded and denatured proteins, in a manner similar to that of molecular chaperones that are involved in protein folding and protein renaturation after stress. Thioredoxin and/o...

Limited proteolysis of the core domain of the 36-kDa protein p36 by trypsin gives a first insight into the structural organization of the four annexin repeats. Trypsin opens only a single peptide bond, situated between residues 204 and 205. The two fragments (of 20 kDa and 15 kDa), each containing two annexin repeats, remain as a tight complex (nicked core), which binds phospholipids in a Ca2(+...

Partial renaturation of urea-denatured bovine pancreatic ribonuclease by polyanions such as phosphate and polyphosphates, as well as by nucleotides, has been observed by Sela, Anfinsen, and Harrington (1). The finding that the velocities of denaturation and renaturation of ribonuclease may be separately and easily measured (2) prompted us to reinvestigate by kinetic methods the manner by which ...