5'-azido-N-1-napthylphthalamic acid, a photolabile analog of n-1-naphthylphthalamic acid. Synthesis and binding properties in Curcurbita pepo L

• Published in: Plant physiology (Bethesda) 1987-09, Vol.85 (1), p.22-25
• Main Authors: Voet, J.G, Howley, K.S, Shumsky, J.S
• Format: Article
• Language: English
• Subjects: AUXINAS; AUXINE; AUXINS; Binding sites; Biological and medical sciences; Carrier proteins; Cell membranes; CELL STRUCTURE; Coleoptiles; Communications; Corn; CUCURBITA PEPO; ESTRUCTURA CELULAR; Fundamental and applied biological sciences. Psychology; Growth regulators; Ligands; Metabolism; Pepos; Photolysis; Plant physiology and development; PROTEINAS; PROTEINE; PROTEINS; Stem cells; STRUCTURE CELLULAIRE
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.85.1.22

A photolabile analog of N-1-naphthylphthalamic acid (NPA), 5′-azido-N-1-naphthylphthalamic acid (Az-NPA), has been synthesized and characterized. This potential photoaffinity label for the plasma membrane NPA binding protein competes with [3H]NPA for binding sites on Curcurbita pepo L. (zucchini) hypocotyl cell membranes with K0.5 = 2.8 × 10-7 molar. The K0.5 for NPA under these conditions is 2 × 10-8 molar, indicating that the affinity of Az-NPA for the membranes is only 14-fold lower than NPA. While the binding of Az-NPA to NPA binding sites is reversible in the dark, exposure of the Az-NPA treated membranes to light results in a 30% loss in [3H]NPA binding ability. Pretreatment of the membranes with NPA protects the membranes against photodestruction of [3H]NPA binding sites by Az-NPA supporting the conclusion that Az-NPA destroys these sites by specific covalent attachment.