Unexpected Di-biotinylation of Angiotensin II by N-Hydroxysulfosuccinimide (sulfo-NHS) linked Biotin Reagents

摘要

An unexpected di-biotinylation on tyrosine of Angiotensin II by N-Hydroxysulfosuccinimide linked biotin reagents was observed and confirmed by LC-MS. Both the unexpected and expected biotinylations occurred primary amine were nearly completed within 1 minute at pH 8. The biotin modification on tyrosine of Angiotensin II can be removed by dithiothreitol (DTT) reduction, unlike that on primary amines, which are stable upon reduction treatment. The histidine adjacent to the tyrosine (Y-I-H) in Angiotensin II probably enhances neucleophilic reactivity of the hydroxyl group towards sulfoNHS-biotin. Future work will be carried to test this hypothesis.