Sentence:  Treatment of the conjugates with ethyl acetate , and the conjugates ( which had been passed through Dowex-2-chloride ) with mouse liver powder , sweet clover crown gall tissue powder , or healthy sweet clover <WSD>proteins</WSD> did not satisfactorily remove nonspecifically staining substances in the conjugates . 
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