Crystal structures of an enantioselective Fab-fragment in free and complex forms

Tarja Parkkinen, Tarja Nevanen, Anu Koivula, Juha Rouvinen (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

15 Citations (Scopus)

Abstract

Enantioselective antibodies can separate the enantiomers of a chiral compound in a highly specific manner. We have recently reported the cloning and applications of a recombinant Fab-fragment, ENA11His, in the enantioseparation of a drug candidate, finrozole, which contains two chiral centers. Here, the crystal structures of this enantioselective antibody Fab-fragment are determined in the absence of the hapten at a resolution of 2.75 Å, and in the presence of the hapten at 2.05 Å resolution. The conformation of the protein was found to be similar in both free and complex forms. The hapten molecule was tightly bound in a deep cleft between the light and heavy chains of the Fab-fragment. The complex structure also allowed us to describe the molecular basis for enantioselectivity and to deduce the absolute configurations of all the four different stereoisomers (a–d) of finrozole. The ENA11His antibody fragment selectively binds the SR (a) enantiomer from the racemic mixture of a and d-enantiomers, thus allowing separation from the pharmacologically most active RS enantiomer (d). In particular, Asp95 and Asn35 of the H-chain in the ENA11 His antibody seem to provide this specificity through hydrogen bonding.
Original languageEnglish
Pages (from-to)471-480
JournalJournal of Molecular Biology
Volume357
Issue number2
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

Keywords

  • enantioselective antibody
  • Fab-fragment
  • complex
  • crystal structure
  • finrozole

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