Sentence:  The strip sections containing a given <WSD>protein</WSD> were pooled , eluted with 0.5 ml of isotonic saline , and the eluates were tested for antibody activity . 
Meaning of the word marked with <WSD> tags:  any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes