Glycogen of the Edible Mussel,Mytilus Edulis,L.

Abstract

Whether or not all glycogens are identical has been investigated repeatedly, 1 but no general agreement has been reached. The report by Samec and Isajevie 2 that dog-liver glycogen contains 0.721% P₂O₅suggests the possibility that the question of the identity of all glycogens may be solved by ascertaining their respective phosphorus contents. The purpose of the present investigation was to compare the phosphorus content of Mytilus glycogen with that of the glycogen examined by Samec and Isajevic.

Samec and Isajevic give no information concerning the method by which their glycogen was prepared. The Mytilus glycogen used in the present investigation was prepared by the method of Pflüger, as modified by Starkenstein and Henze. 3 In addition, it was repeatedly precipitated from slightly acidulated solutions. Difficulties were encountered in filtration so that the material was unavoidably exposed for a long time to strong KOH. The glycogen finally obtained had a P₂O₅ content of 0.1168% as determined by the method of Embden and an ash content of 0.25%. It was white and contained iron, calcium and phosphorus.

Certain investigators have obtained glycogen free from ash. The attempt was, therefore, made to remove the ash of Mytilus glycogen by electrodialysis with ultrafiltration in a Bechold-König apparatus, using a 10% acetic acid-collodion solution for the membranes. Dialysis was continued until the readings of the ammeter connected with the apparatus were constant, which took 4 to 5 hours. The dialyzate contained phosphorus and calcium. Samec and Isajevic also electrodialyzed glycogen and found that it separated into a sol and a gel layer, the material in the sol containing more than five times as great a percentage of P₂O₅ as the material in the gel. Mytilus glycogen did not separate into two layers in this way, perhaps because during dialysis the direction of the current was frequently changed. The solutions obtained could not be precipitated with alcohol until after the addition of a few drops of a 1% ammonium acetate solution.