Molecular Biology Institute, University of California, Los Angeles, Los Angeles, United States of America.Pest description and crop damage The tomato hornworm larvae is over 3 inches long when full grown, green, with eight chevron-shaped white stripes and a distinctive large "horn" on the posterior end of its body. in a form suitable for a high resolution structure determination. Crystallization of insecticyanin from the hemolymph of the tobacco hornworm Manduca sexta L.The biliverdin lies towards the open end of the beta-barrel with its two propionate side chains pointing towards the solvent and it adopts a rather folded conformation, much like a heme. The electron density attributable to the chromophore is unambiguous and shows that it is indeed the gamma-isomer of biliverdin. Interestingly the overall three-dimensional fold of the insecticyanin subunit shows remarkable similarity to the structural motifs of bovine beta-lactoglobulin and the human serum retinol-binding protein. ![]() ![]() The individual subunits have overall dimensions of 44 A X 37 A X 40 A and consist primarily of an eight-stranded anti-parallel beta-barrel flanked on one side by a 4.5-turn alpha-helix. The map clearly shows that insecticyanin is a tetramer with one of its molecular 2-fold axes coincident to a crystallographic dyad. All 189 amino acids have been fitted to the electron density map. Its three-dimensional structure has now been solved to 2.6 A resolution using the techniques of multiple isomorphous replacement, non-crystallographic symmetry averaging about a local 2-fold rotation axis and solvent flattening. Insecticyanin, a blue biliprotein isolated from the tobacco hornworm Manduca sexta L., is involved in insect camouflage.
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