R. Xu, X. Huang, T. D. Morgan
May 1, 1996
Citations
1
Influential Citations
41
Citations
Journal
Archives of biochemistry and biophysics
Abstract
When insects harden or sclerotize their exoskeletons, quinones of N-acetylated catecholamines such as N-acetyldopamine (NADA) undergo nucleophilic addition reactions with amino acids such as histidine in cuticular proteins. To determine the products that might form when this type of reaction occurs during cuticle sclerotization, the reactions between electrochemically prepared NADA quinone and N-acetylistidine (NAcH), a protein model nucleophile, have been investigated at pH 7. Two major products, 6-[N-(N-acetylhistidyl)]-N-acetyldopamine and 2-[N-(N-acetylhistidyl)]-N-acetyldopamine, were purified by semipreparative reversed-phase liquid chromatography and identified by mass spectrometry and nuclear magnetic resonance spectroscopy. The relative molar ratio of the C(6) mono-addition adduct to the C(2) mono-addition adduct is 87:13. UV/vis spectroscopic analysis shows that both products have an absorption maximum at 284 nm. Cyclic voltammetry shows that these adducts are oxidized less readily than NADA.