Through the eye of an electrospray needle: mass spectrometric identification of the major peptides and proteins in the milk of the one-humped camel (Camelus dromedarius)

摘要

Themilk of the one-humped camel (Camelus dromedarius) reportedly offersmedicinal benefits, perhaps because of its unique bioactive components.Milk proteinswere determined by (1) two-dimensional gel electrophoresis and peptidemassmapping and (2) liquid chromatography-tandem mass spectrometry (LC-MS/MS) following one-dimensional polyacrylamide gel electrophoresis. Over 200 proteins were identified: some known camel proteins including heavy-chain immunoglobulins and others exhibiting regions of exact homology with proteins from other species. Indigenous peptides were also identified following isolation and concentration by two strategies: (1) gel-eluted liquid fraction entrapment electrophoresis and (2) small-scale electrophoretic separation. Extracts were analyzed by LC-MS/MS and peptides identified by matching strategies, by de novo sequencing and by applying a sequence tag tool requiring similarity to the proposed sequence, but not an exact match. A plethora of protein cleavage products including some novel peptides were characterized. These studies demonstrate that camel milk is a rich source of peptides, some of which may serve as nutraceuticals.