CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF PEANUT AGGLUTININ-N6-BENZYLAMINOPURINE COMPLEX

Preliminary diffraction data collected on peanut agglutinin (PNA) crystals grown in the presence of N6-benzylaminopurine (BAP) indicate a monoclinic cell (P2) with a = 67·0 A ̊, b = 35·2 A ̊, c = 65·8 A ̊ and β = 68·6 °. This is the first example of a legume lectin crystallized with a bound phytohormone. Crystals of PNA grown previously in the presence of lactose had an orthorhombic space group (P21212) with a = 128·8 A ̊, b = 126·0 A ̊ and c = 76·l A ̊ and one tetramer per asymmetric unit. The Vm value for the PNA-BAP crystals is 2·62 Å3/Da. assuming one monomer of PNA per asymmetric unit. Thus, while the PNA-lactose complex crystallized as tetramers, the PNA-BAP complex has, at most, dimers in the crystal. These results indicate that BAP, a naturally occurring phytohormone, can modify the quaternary structure of PNA by dissociation and change its carbohydrate valence. © 1991.