tailieunhanh - Báo cáo khoa học: Implication for buried polar contacts and ion pairs in hyperthermostable enzymes

Understanding the structural basis of thermostability and thermoactivity, and their interdependence, is central to the successful future exploitation of extremophilic enzymes in biotechnology. However, the structural basis of thermostability is still not fully characterized. | MINIREVIEW Implication for buried polar contacts and ion pairs in hyperthermostable enzymes Ikuo Matsui and Kazuaki Harata BiologicalInformation Research Center National institute of Advanced Industrial science and Technology AIST Ibaraki Japan Keywords accessible surface area buried polar contact hyperthermophilic archaea hyperthermostable enzyme ion pair molecular structure Pyrococcus subunit interaction thermostability Correspondence I. Matsui BiologicalInformation Research Center NationalInstitute of Advanced Industrial science and Technology AIST Tsukuba Ibaraki 305 Japan Fax 81 29 8616151 Tel 81 29 8616142 E-mail ik-matsui@ Received 28 February 2007 accepted 17 May 2007 Understanding the structural basis of thermostability and thermoactivity and their interdependence is central to the successful future exploitation of extremophilic enzymes in biotechnology. However the structural basis of thermostability is still not fully characterized. Ionizable residues play essential roles in proteins modulating protein stability folding and function. The dominant roles of the buried polar contacts and ion pairs have been reviewed by distinguishing between the inside polar contacts and the total intramolecular polar contacts and by evaluating their contribution as molecular determinants for protein stability using various protein structures from hyperthermophiles thermophiles and mesophilic organisms. The analysis revealed that the remarkably increased number of internal polar contacts in a monomeric structure probably play a central role in enhancing the melting temperature value up to 120 C for hyperthermophilic enzymes from the genus Pyrococcus. These results provide a promising contribution for improving the thermostability of enzymes by modulating buried polar contacts and ion pairs. doi Introduction Hyperthermophiles grow optimally at temperatures of 80-110 C 1 . Only represented by bacterial and archaeal species these .