title: Key role of barstar Cys-40 residue in the mechanism of heat denaturation of bacterial ribonuclease complexes with barstar.
abstract: The mechanism by which barnase and binase are stabilized in their complexes with barstar and the role of the Cys-40 residue of barstar in that stabilization have been investigated by scanning microcalorimetry. Melting of ribonuclease complexes with barstar and its Cys-82-Ala mutant is described by two 2-state transitions. The lower-temperature one corresponds to barstar denaturation and the higher-temperature transition to ribonuclease melting. The barstar mutation Cys-40-Ala, which is within the principal barnase-binding region of barstar, simplifies the melting to a single 2-state transition. The presence of residue Cys-40 in barstar results in additional stabilization of ribonuclease in the complex.
authors: Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow.
authors: I I
authors: II
authors: Protasevich
authors: A A
authors: AA
authors: Schulga
authors: L I
authors: LI
authors: Vasilieva
authors: K M
authors: KM
authors: Polyakov
authors: V M
authors: VM
authors: Lobachov
authors: R W
authors: RW
authors: Hartley
authors: M P
authors: MP
authors: Kirpichnikov
authors: A A
authors: AA
authors: Makarov
mesh_terms: D000409:Alanine / Q000235:genetics; D001407:Bacillus / Q000201:enzymology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000235:genetics / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism*; D004795:Enzyme Stability; D006361:Heating; D016297:Mutagenesis, Site-Directed; D011489:Protein Denaturation; D012260:Ribonucleases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C057438:barstar protein, Bacillus amyloliquefaciens; D004722:Endoribonucleases; D012260:Ribonucleases; C019760:Bacillus amyloliquefaciens ribonuclease; C022543:ribonuclease T(2); D003545:Cysteine; D000409:Alanine