Tags

Type your tag names separated by a space and hit enter

A thermodynamic analysis of conformational change due to the alpha 2 beta 2 complex formation of tryptophan synthase.
Eur J Biochem. 1996 Aug 15; 240(1):63-70.EJ

Abstract

A characteristic property of the tryptophan synthase alpha 2 beta 2 complex is the mutual activation of the alpha and beta subunit upon complex formation. It has been speculated that this mutual activation results from the conformational change due to the alpha/beta subunit interaction. To elucidate this mechanism, we investigated the thermodynamic parameters of association for the various combinations of the alpha and beta subunits from Escherichia coli and Salmonella typhimurium using isothermal titration calorimetry. The negative association enthalpy of the S. typhimurium alpha subunit with the beta subunit from E. coli (or S. typhimurium) was about 20 kJ mol-1 larger than that of the E. coli alpha subunit at 40 degrees C. However, the favorable enthalpy of the S. typhimurium alpha subunit was perfectly compensated by the unfavorable association entropy, therefore, the Gibbs energy of association was similar to that of the E. coli alpha subunit. Furthermore, the site-directed mutagenesis study revealed that a single mutation (K109N; [Asn109] alpha subunit) of the E coli alpha subunit at the subunit interface from E. coli to the S. typhimurium type could change the characteristics of the thermodynamic parameters of association to the S. typhimurium alpha subunit type. The heat-capacity changes of the association of the alpha subunit with the beta subunit were quite great, 6.37-8.21 kJ mol-1 K-1, compared with that due to a decrease in accessible surface area in the subunit interface. The analysis of the thermodynamic parameters of association suggested that the complex formation couples with the folding (rearrangements) of the alpha subunit monomer or/and beta subunit dimer.

Authors+Show Affiliations

Institute for Protein Research, Osaka University, Japan.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8797836

Citation

Hiraga, K, and K Yutani. "A Thermodynamic Analysis of Conformational Change Due to the Alpha 2 Beta 2 Complex Formation of Tryptophan Synthase." European Journal of Biochemistry, vol. 240, no. 1, 1996, pp. 63-70.
Hiraga K, Yutani K. A thermodynamic analysis of conformational change due to the alpha 2 beta 2 complex formation of tryptophan synthase. Eur J Biochem. 1996;240(1):63-70.
Hiraga, K., & Yutani, K. (1996). A thermodynamic analysis of conformational change due to the alpha 2 beta 2 complex formation of tryptophan synthase. European Journal of Biochemistry, 240(1), 63-70.
Hiraga K, Yutani K. A Thermodynamic Analysis of Conformational Change Due to the Alpha 2 Beta 2 Complex Formation of Tryptophan Synthase. Eur J Biochem. 1996 Aug 15;240(1):63-70. PubMed PMID: 8797836.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A thermodynamic analysis of conformational change due to the alpha 2 beta 2 complex formation of tryptophan synthase. AU - Hiraga,K, AU - Yutani,K, PY - 1996/8/15/pubmed PY - 1996/8/15/medline PY - 1996/8/15/entrez SP - 63 EP - 70 JF - European journal of biochemistry JO - Eur J Biochem VL - 240 IS - 1 N2 - A characteristic property of the tryptophan synthase alpha 2 beta 2 complex is the mutual activation of the alpha and beta subunit upon complex formation. It has been speculated that this mutual activation results from the conformational change due to the alpha/beta subunit interaction. To elucidate this mechanism, we investigated the thermodynamic parameters of association for the various combinations of the alpha and beta subunits from Escherichia coli and Salmonella typhimurium using isothermal titration calorimetry. The negative association enthalpy of the S. typhimurium alpha subunit with the beta subunit from E. coli (or S. typhimurium) was about 20 kJ mol-1 larger than that of the E. coli alpha subunit at 40 degrees C. However, the favorable enthalpy of the S. typhimurium alpha subunit was perfectly compensated by the unfavorable association entropy, therefore, the Gibbs energy of association was similar to that of the E. coli alpha subunit. Furthermore, the site-directed mutagenesis study revealed that a single mutation (K109N; [Asn109] alpha subunit) of the E coli alpha subunit at the subunit interface from E. coli to the S. typhimurium type could change the characteristics of the thermodynamic parameters of association to the S. typhimurium alpha subunit type. The heat-capacity changes of the association of the alpha subunit with the beta subunit were quite great, 6.37-8.21 kJ mol-1 K-1, compared with that due to a decrease in accessible surface area in the subunit interface. The analysis of the thermodynamic parameters of association suggested that the complex formation couples with the folding (rearrangements) of the alpha subunit monomer or/and beta subunit dimer. SN - 0014-2956 UR - https://www.unboundmedicine.com/medline/citation/8797836/A_thermodynamic_analysis_of_conformational_change_due_to_the_alpha_2_beta_2_complex_formation_of_tryptophan_synthase_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0014-2956&date=1996&volume=240&issue=1&spage=63 DB - PRIME DP - Unbound Medicine ER -