title: Solution structure of a photo-switchable insect kinin thioxo-analog.
abstract: he photo-switchable insect kinin thioxo-analog Phe(1)-Tyr(2)-Psi[CS-N]-Pro(3)-Trp(4)-Gly(5)-NH(2) (Psi[CS-N](2)-Kinin) can change from ground state to photo-stationary state by following a pulse of UV Radiation and its bioactivity increases simultaneously. To investigate the conformation-activity relationship, the solution structure of its ground state was determined by two-dimensional NMR spectroscopy. In contrast, the photo-stationary state could not be determined because of its relatively fast thermal reisomerization. The molecular dynamics-calculated structures based on NMR constraints demonstrate that the trans Pro conformer is the predominant conformation for the ground state in aqueous solution, which was also confirmed by the very weak signal of the cis Pro conformer in the spectroscopy. The aromatic side chains of residues 2 and 4 form an electrostatic interaction rather than 1 and 4. The results explain the low bioactivity before UV Radiation, and indicate the importance of the 1-4 electrostatic interaction for the activity of insect kinins.
authors.affiliation: Institute of Biochemistry and Molecular Biology, School of Life Sciences, Lanzhou University, 222 Tianshui South Road, Lanzhou 730000, China.
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Cong
authors.forename: Yun
authors.initials: Y
authors.lastname: Huang
authors.forename: Longfei
authors.initials: L
authors.lastname: Yang
authors.forename: Dan
authors.initials: D
authors.lastname: Ye
authors.forename: Shouliang
authors.initials: S
authors.lastname: Dong
mesh_terms: D000818:Animals; D019476:Insect Proteins / Q000737:chemistry*; D007705:Kinins / Q000737:chemistry*; D007915:Lepidoptera / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011487:Protein Conformation; D012996:Solutions; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D019476:Insect Proteins; D007705:Kinins; D012996:Solutions