The Periodate oxidation of gelatin extracted from bone
Aronson, Robert Bernard
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The purpose of this investigation was to study the periodate oxidation of gelatin obtained from bovine bones in order to determine the conditions necessary for complete oxidation of the hydroxylysine content of the gelatin. The following results were obtained: 1. Amino acid analysis of the bone gelatin preparation agreed with values for bone gelatin found in the literature. 2. The carbohydrate content of the gelatin preparation, expressed as glucose, was determined and found to be .074 umoles of glucose per milligram of nitrogen. 3. Oxidation of the bovine, bone gelatin preparation with sodium periodate in 0.1 N NaOH showed that approximately 65 per cent of the hydroxylysine in a given sample was destroyed in one hour. 4. Kinetic analysis of the periodate reaction in 0.1 N NaOH showed that the oxidation was not a simple first- or second-order reaction. An analysis of the curve, obtained in testing for a first-order reaction, resulted in two first-order components. One of these components had a reaction-rate which was 14 times faster than the rate of the other. The two-component analysis was preferred over others because of its simplicity. 5. Kinetic analysis of periodate reactions at pH levels between 7 and 12 also failed to show that the oxidations were simple first-order reactions. Analysis of the first-order graphs of these reactions made in the same manner as with 0.1 N NaOH showed that the slower component reacted very slowly or not at all. 6. An attempt to correct the first-order reaction graph of gelatin oxidized in 0.1 N NaOH for formaldehyde possibly produced from carbohydrate did not produce a straight line. Thus the carbohydrate was not considered responsible for the failure of the reaction to be firstorder. 7. The results of the oxidations in this study led us to the hypothesis that the hydroxylysine of our bone gelatin exists in two forms: one, which has the reactive site of its side-chain free, is readily available to oxidation by periodate; the other, with its reactive site chemically bound, reacts with periodate at a rate which is dependent on the rapidity with which these bonds may be broken. The implications which these studies have concerning the chemical nature of hydroxylysine in bone gelatin and the factors interfering in periodate oxidations of this gelatin are discussed.
Thesis (Ph.D.)--Boston University..