STUDIES ON THE DEXTRANSUCRASE OF LEUCONOSTOC DEXTRANICUM

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Abstract
A simplified method for isolation of the dextran-synthesizing enzyme system of L. dextranicum, strain elai was devised. Results indicated that for this strain of Leuconostoc, the larger fraction of the enzyme exists in association with cells. By means of chelating agents, and also by prolonged dialysis, it was shown that dextransucrase does not require a metal activator, nor does it contain dialyzable coenzymes. The enzyme for sucrose was unable to form dextran from various mixtures of hexose mono- and di-phosphates with glucose or fructose. The use of whole-cell enzyme concentrates in these expts. indicated that L. dextranicum strain elai does not contain a sucrose phosphorylase. The addition of either of the constituent monosaccharides of sucrose to enzyme-sucrose mixtures resulted in an inhibition of dextran synthesis, glucose having the greater inhibitory effect. The pH for optimal activity of the enzyme was found to be 5.6. The Michaelis dissociation constant was calculated to have a value of 15.9 mM.
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