Acetaldehyde‐enkephalins: pronounced changes in the opiate activity of methionine‐enkephalin and leucine‐enkephalin on reaction with acetaldehyde

Acetaldehyde-enkephalins: structure proof and some conformational deductions from one- and two-dimensional proton nuclear magnetic resonance spectra

“…Analysis of the NMR was used to assign the resonances. Suitable manipulation of data suggests that the folded conformation characteristic of the two-dimensional data allowed analysis of -CH resonances native enkephalins in dimethyl-i/6 sulfoxide is not important which were completely buried under a water signal and of in these derivatives.e opioid pentapeptides (1) and Leu5enkephalin (2) react rapidly with aqueous solutions of acetaldehyde to yield adducts with much reduced opiate activity (Summers & Hayes, 1980), and three of us have recently presented some 100-MHz proton NMR evidence that these adducts have the 2-methylimidazolidin-4-one structure shown in Scheme I, each adduct being formed as a mixture of the 2R, 5S and 2S,5S diastereoisomers (Summers et al, 1980).…”

“…e opioid pentapeptides (1) and Leu5enkephalin (2) react rapidly with aqueous solutions of acetaldehyde to yield adducts with much reduced opiate activity (Summers & Hayes, 1980), and three of us have recently presented some 100-MHz proton NMR evidence that these adducts have the 2-methylimidazolidin-4-one structure shown in Scheme I, each adduct being formed as a mixture of the 2R, 5S and 2S,5S diastereoisomers (Summers et al, 1980).…”