Breakdown of paramylon and laminarin by digestive enzymes of Lamellibranchs — an important ecological feature

A quest for enzymes or enzyme mixtures capable of attacking paramylon, the insoluble and chemically inert reserve polysaccharide of the Euglenids, in its raw state, has yielded positive results only for the stomach extracts of certain freshwater Lamellibranchs. These juices converted the doughnut-shaped native paramylon granules to slender rings of astounding regularity. This can be considered as a dramatization of the lytic events taking place during the mobilization of paramylon bodies in living Euglenid cells and giving rise to slender rings there; it militates against the idea that paramylon rings in Euglenid cells are produced on, or in, preformed protoplasmic structures of the same shape. Crop juice of the snail Helix pomatia and sugar gland juice of Cryptochiton stelleri exerted only a slight etching effect on paramylon granules. Stomach juice of crayfish (Astacus) and preparations from several species of bacteria, molds and higher plants were found to be inactive, although all of them (like the Lamellibranch enzymes and those from Helix and Cryptochiton) were very active towards dissolved laminarin. For all the animal laminarases tested, including the Euglena enzyme, the pHoptimum was close to 5. In experiments of 1 hr. duration, the temperature optimum for all the molluscan enzymes was remarkably high, namely 55-60° C. Filter paper chromatography revealed that, with the exception of the Euglena enzyme, the animal enzymes act as ”endo-laminarases”, giving rise to a mixture of several oligosaccharides before their substrate (laminarin) is ultimately converted to glucose.