Isolation of a pancreatic protein that has remarkable growth promoting properties has been reported recently by White and Sayers1 of Yale University. The protein was originally obtained by Kazel2 as an insoluble residue after acid-alcohol extraction of the finely minced frozen beef pancreas. It was rendered lipid free by subsequent continuous extraction with acetone. Partial analysis of the oven dried (105 C.) end product showed that it contained an average of 16.2 per cent of nitrogen, 1.56 per cent of phosphorus, 1.56 per cent of tryptophan and 3.85 per cent of tyrosine, with an atomic purine nitrogen: phosphorus ratio similar to that calculated from Loring's data3 for certain nucleic acids. Purine determinations suggested a nucleic acid content of 10 to 14 per cent. Recently weaned male white rats were placed on a basal diet containing 22 per cent of this protein or the nitrogenous equivalents of other
GROWTH ACCELERATING PROTEIN. JAMA. 1943;122(4):232–233. doi:10.1001/jama.1943.02840210024009
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