Action Patterns of Sugarcane Acid Invertase

Abstract

Chromatographic studies were made of the products of sugarcane acid invertase. The enzyme was precipitated from water extracts of lyophilized meristem tissues by ammonium sulfate. The 38- to 52-percent fraction was retained and dialyzed for 2 hours against distilled water. Substrates tested included sucrose, glucose, fructose, galactose, melezitose, raffinose, turanose, stachyose, and inulin. Samples from the digests were inactivated by boiling, spotted on Whatman No. 1 chromatography paper, and irrigated by the descending technique with butanol-pyridine-water (6:4:3 v/v). Sugars were revealed on chromatograms by the silver nitrate dip method. Two reducing sugars were produced when invertase acted upon sucrose, but neither corresponded to reference glucose. Both products revealed staining and mobility properties similar to reference fructose. Evidence was obtained showing that glucose is acted upon by a second enzyme to yield a sugar similar to galactose. The possibility of a nucleotide-derivative epimerase is discussed. Other sugars acted upon were raffinose and stachyose, thus confirming the invertase as a ß-fructosidase. Four products appeared when raffinose and stachyose were hydrolyzed. Melezitose yielded no detectable reducing sugars, throwing doubt on the presence of an α-glucosidase. Turanose and inulin were not attacked. Significance of the invertase data is briefly discussed.