The proteins of the pea (Pisum Sativum) / by Thomas B. Osborne and Isaac F. Harris.

  • Thomas Burr Osborne
Catalogue details

Licence: Public Domain Mark

Credit: The proteins of the pea (Pisum Sativum) / by Thomas B. Osborne and Isaac F. Harris. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    4/8 page 216
    when redissolved and precipitated by dialysis, gave 0.69 gram of substance which was wholly soluble in dilute sodium chloride solution, coagulated by heating to 100° and when dried at 110° had the following composition; C, 52.17; H, lost; N, 17.08 per cent. A repetition of this experiment, making the separation at seven-tenths saturation, gave essentially the same results, namely, 26.5 grams of legumin, containing C, 51.89; H, 6.83: N, 17.78 per cent, and 9.5 grams of vicilin, containing C, 52.35; H, 7.15; N, 16.90 per cent. A third extraction gave at five-tenths saturation 17.76 grams of globulin containing 17.77 per cent of nitrogen; between five- tenths and six-tenths 9.62 grams containing 17.99 P^r cent of nitrogen; between seven-tenths and eight-tenths 10.03 grams containing 17.18 per cent nitrogen, and between eight-tenths and complete saturation 7.46 grams, containing 17.00 per cent of nitrogen. It is thus evident that separation by fractional precipitation with ammonium sulphate yields products of the same composi- tion and properties as those formerly obtained by fractional precipitation from sodium chloride solutions and as this separa- tion is effected without difficulty and with little loss of substance, it affords an excellent method for preparing large quantities of these two proteins in as pure a state as it is possible to obtain them in any way known to us. We accordingly prepared large quantities of these proteins for hydrolysis by extracting the pea-meal with 10 per cent sodium chloride solution, filtering the extract perfectly clear and dialyz- ing until nearly all of the chlorides were removed. The dial3''sis precipitate was then dissolved in one-tenth saturated ammonium sulphate solution, the resulting solution filtered clear, and enough ammonium sulphate crystals dissolved in it to bring it to six- tenths saturation. The precipitate thus produced was dissolved in sodium chloride solution and, after filtering perfectly clear, the solution was dia- lyzed until free from chloride. The resulting precipitate of legumin was then washed with water, dilute and absolute alcohol and dried over sulphuric acid. The filtrate from the precipitate produced by six-tenths satu- ration with ammonium sulphate was completely saturated with
    digitised image 1
    digitised image 2
    digitised image 3