The minimum length of an unbranched amylose-type chain which functions as substrate for Q-enzyme has been determined by two methods. It is shown that the minimum length for rapid transglucosidation by Q-enzyme is about 40 glucose units. A slow branching action is observed when Q-enzyme acts upon substrates of shorter chain-length. Thus, a synthetic, linear, 28-unit dextrin was branched at a much slower rate than was a 58-unit dextrin.
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