TAILIEUCHUNG - Báo cáo khoa học: The essential tyrosine-containing loop conformation and the role of the C-terminal multi-helix region in eukaryotic phenylalanine ammonia-lyases

Besides the post-translationally cyclizing catalytic Ala-Ser-Gly triad, Tyr110 and its equivalents are of the most conserved residues in the active site of phenylalanine ammonia-lyase (PAL, EC ), histidine ammonia-lyase (HAL, EC ) and other related enzymes. The Tyr110Phe muta-tion results in the most pronounced inactivation of PAL indicating the importance of this residue. | iFEBS Journal The essential tyrosine-containing loop conformation and the role of the C-terminal multi-helix region in eukaryotic phenylalanine ammonia-lyases Sarolta Pilbak1 Anna Tomin1 Janos Rétey2 and László Poppe1 1 Institute for Organic Chemistry and Research Group for Alkaloid Chemistry Budapest University of Technology and Economics Hungary 2 Institute of Organic Chemistry University of Karlsruhe Germany Keywords homology model loop conformation phenylalanine ammonia-lyase regulation structure Correspondence L. Poppe Institute for Organic Chemistry and Research Group for Alkaloid Chemistry Budapest University of Technology and Economics Gellert ter 4 H-1111 Budapest Hungary Fax 36 1 4633297 Tel 36 1 4632229 E-mail poppe@ Received 20 October 2005 revised 16 December 2005 accepted 3 January 2006 doi Besides the post-translationally cyclizing catalytic Ala-Ser-Gly triad Tyr110 and its equivalents are of the most conserved residues in the active site of phenylalanine ammonia-lyase PAL EC histidine ammonialyase HAL EC and other related enzymes. The Tyr110Phe mutation results in the most pronounced inactivation of PAL indicating the importance of this residue. The recently published X-ray structures of PAL revealed that the Tyr110-loop was either missing for Rhodospridium torulo-ides or far from the active site for Petroselinum crispum . In bacterial HAL 500 amino acids and plant and fungal PALs 710 amino acids a core PAL HAL domain 480 amino acids with 30 sequence identity along the different species is common. In plant and fungal PAL a 100-residue long C-terminal multi-helix domain is present. The ancestor bacterial HAL is thermostable and in all of its known X-ray structures a Tyr83-loop-in arrangement has been found. Based on the HAL structures a Tyr110-loop-in conformation of the P. crispum PAL structure was constructed by partial homology modeling and the static and dynamic behavior of the loop-in .

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