tailieunhanh - Báo cáo khoa học: Crystal structure determination and inhibition studies of a novel xylanase and a-amylase inhibitor protein (XAIP) from Scadoxus multiflorus

A novel plant protein isolated from the underground bulbs of Scadoxus multiflorus, xylanase and a-amylase inhibitor protein (XAIP), inhibits two structurally and functionally unrelated enzymes: xylanase and a-amylase. The mature protein contains 272 amino acid residues which show sequence identities of 48% to the plant chitinase hevamine and 36% to xylanase inhibitor protein-I, a double-headed inhibitor of GH10 and GH11 xylanases. | ễFEBS Journal Crystal structure determination and inhibition studies of a novel xylanase and a-amylase inhibitor protein XAIP from Scadoxus multiflorus Sanjit Kumar Nagendra Singh Mau Sinha Divya Dube S. Baskar Singh Asha Bhushan Punit Kaur Alagiri Srinivasan Sujata Sharma and Tej P. Singh Department of Biophysics All India Institute of MedicalSciences New Delhi India Keywords crystal structure enzyme inhibition TIM barrel fold xylanase a-amylase Correspondence T. P. Singh Department of Biophysics All India Institute of MedicalSciences Ansari Nagar New Delhi - 110 029 India Fax 91 11 2658 8663 Tel 91 11 2658 8931 E-mail Database The complete nucleotide and derived amino acid sequences of XAIP are available in the EMBL GenBank DDBJ databases under the accession number EU663621 Structural data are available in the Protein Data Bank database under the accession numbers 3HU7 and 3M7S. Received 18 March 2010 revised 27 April 2010 accepted 29 April 2010 doi A novel plant protein isolated from the underground bulbs of Scadoxus multiflorus xylanase and a-amylase inhibitor protein XAIP inhibits two structurally and functionally unrelated enzymes xylanase and a-amylase. The mature protein contains 272 amino acid residues which show sequence identities of 48 to the plant chitinase hevamine and 36 to xylanase inhibitor protein-I a double-headed inhibitor of GH10 and GH11 xylanases. However unlike hevamine it is enzymatically inactive and unlike xylanase inhibitor protein-I it inhibits two functionally different classes of enzyme. The crystal structure of XAIP has been determined at A resolution and refined to Rcryst and Rfree factors of and respectively. The polypeptide chain of XAIP adopts a modified triosephosphate isomerase barrel fold with eight b-strands in the inner circle and nine a-helices forming the outer ring. The structure contains three cis peptide bonds Gly33-Phe34 Tyr159-Pro160 and .