Two Structures of Alliinase from Alliium sativum L.: Apo Form and Ternary Complex with Aminoacrylate Reaction Intermediate Covalently Bound to the PLP Cofactor.

摘要: Abstract Alliinase (alliin lyase EC 4.4.1.4), a PLP-dependent α, β-eliminating lyase, constitutes one of the major protein components garlic ( Alliium sativum L. ) bulbs. The enzyme is homodimeric glycoprotein and catalyzes conversion specific non-protein sulfur-containing amino acid alliin ((+S)-allyl- L -cysteine sulfoxide) to allicin (diallyl thiosulfinate, well known biologically active component freshly crushed garlic), pyruvate ammonia. was crystallized in presence (+S)-allyl- -cysteine, forming dendrite-like monoclinic crystals. In addition, intentionally produced apo -enzyme tetragonal form. These structures alliinase with associated glycans were resolved 1.4 A 1.61 A by molecular replacement. Branched hexasaccharide chains N-linked Asn146 trisaccharide Asn328 are seen. structure found similar “short chain complex vacuole type” oligosaccharide most commonly seen plant glycoproteins. An unexpected state site has been observed present structure. electron density region cofactor made it possible identify moiety as aminoacrylate intermediate covalently bound PLP cofactor. It be stabilized large number interactions surrounding residues. Moreover, existence expected internal aldimine bond between e-amino group Lys251 aldehyde ruled out on basis distinct separation Lys251. cavity -form nearly identical that holo -form, two sulfate ions, an acetate several water molecules from crystallization conditions replace mimic