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The CD method has been used to study the conformation of the pentapeptido Asn-Ala-Gly-Ala-Asn(NAGAN) and the tetrapeptides Asn-Ala-Gly-Ala(NAGA) and Asn-D-Ala-Gly-Ala-NH_2(NDAGA) in solution. At low pH the far UV CD speetra of aqueous solutions of NAGAN show a positive extremum at 215 nm and a negative extremum at 232.5 nm. Under this condition, the molecule of NAGAN may assume a β-turn structure. In the solution of 90% ethanol or tri-fluoroethanol at pH 5.8, NAGAN reveals CD spectra with a negative 218 nm extremum. The[θ]_218 values are independent of the concentration of NAGAN. Au intramolecular β-pleated sheet-like structure is suggested to explain the negative peak.The CD spectra of NAGA show a single positive band at around 215 nm. The possibility of forming a β-turn by NAGA has been discussed. Only the 196 nm negative extremum canbe seen in the spectra of NDAGA: It seems as if NDAGA is in the form of a random coil.According to the report made by Pan et al. all these peptides possess analgesic
The CD method has been used to study the conformation of the pentapeptido Asn-Ala-Gly-Ala-Asn (NAGAN) and the tetrapeptides Asn-Ala-Gly- Ala (NAGA) and Asn- D-Ala-Gly-Ala- (NDAGA) in solution. At low pH the far UV CD speetra of aqueous solutions of NAGAN show a positive extremum at 215 nm and a negative extremum at 232.5 nm. Under this condition, the molecule of NAGAN may assume a β-turn structure. The [θ] _218 values are independent of the concentration of NAGAN. Au intramolecular β-pleated sheet-like structure is suggested to explain the negative peak. The CD spectra of NAGA show a single positive band at around 215 nm. The possibility of forming a β-turn by NAGA has been discussed. Only the 196 nm negative extremum canbe seen in the spectra of NDAGA: It seems as if NDAGA is in the form of a random coil. Accredited to the report made by Pan et al. All these peptides possess analgesic