Showing papers by "David Shemin published in 1946"
TL;DR: The curve of N15 concentration of the heme versus time can form the basis for a determination of the average life span of the human red blood cell, which was found to be about 127 days.
330 citations
169 citations
134 citations
TL;DR: There has been developed, in the last few years, a method derived from the isotope technique, which allows the estimation of amino acids in protein hydrolysates with an error which can be estimated to be within 1 to 2 per cent.
Abstract: There has been developed, in the last few years, a method derived from the isotope technique, which allows the estimation of amino acids in protein hydrolysates with an error which can be estimated to be within 1 to 2 per cent.l* 2* 3 * 4 , 6 , 8 The validity of the isotope dilution method is based on the fact that the usual laboratory procedures for isolating amino acids do not separate isotope-containing molecules from their normal analogues. Since the isotopic compound is inseparable from its normal analogue, if one adds, for example, glutamic acid labeled with Nl6 to a protein hydrolysate and if a sample of glutamic acid is isolated from the mixture and its N15 excess is determined, it is possible to calculate the amount of glutamic acid (B) originally present in the protein hydrolysate from EQUATION 1, B = [z -11 A
15 citations