The Solution Structure of [ala4]-desdimethylchlamydocin - A H-1-nmr Relaxation Study

Many fungal peptides exhibit plant toxicity in a host-specific manner. Here we report a proton relaxation and two dimensional (2D) n.m.r. study of the [Ala4]-desdimethyl analogue of the fungal tetrapeptide chlamydocin. Interproton distances calculated from n.m.r. parameters agreed substantially with the corresponding distances in the crystalline form of dihydrochlamydocin. A solution conformational analysis was performed based on n.m.r. distance measurements and φ, ψ, and ω angles of the four residues plus χi rotamer populations. These data support the use of proton relaxation parameters as a basis for accurate solution conformational analysis. As a corollary, the data can also indicate within experimental error that the crystal and solution conformations of chlamydocin and the [Ala4]-desdimethyl analogue, respectively, are identical.