Sentence:  The <WSD>proteins</WSD> were extracted with 3 volumes of * * f in * * f to give a nearly neutral extract and precipitated by 80 % saturation with * * f . 
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