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Key role of barstar Cys‐40 residue in the mechanism of heat denaturation of bacterial ribonuclease complexes with barstar
Author(s) -
Protasevich I.I,
Schulga A.A,
Vasilieva L.I,
Polyakov K.M,
Lobachov V.M,
Hartley R.W,
Kirpichnikov M.P,
Makarov A.A
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)00158-1
Subject(s) - barnase , ribonuclease , chemistry , residue (chemistry) , denaturation (fissile materials) , crystallography , isothermal microcalorimetry , stereochemistry , biochemistry , rna , thermodynamics , enthalpy , physics , nuclear chemistry , gene
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.