The reversible inhibition of β-malt-amylase by ascorbic acid and related compounds

Preparation of fi-malt-amylase.The enzyme was prepared from ungerminated barley by a method based on that of van Klinkenberg [1931].The seed coat, aleurone layer and most of the embryonic tissue were removed from a specimen of high-grade malting barley by grinding in an abrasive mill.The product, which resembled commercial "Pearl Barley", was ground to a fine flour.200 g. of the flour were extracted with 700 ml.50 % ethyl alcohol for 2 hours.After centrifuging, the residue was again extracted with 250 ml.50 % alcohol and again centrifuged down.The supernatant liquors were combined and the enzyme precipitated by the addition of alcohol to a final concentration of 80 %.The precipitate was removed on the centrifuge and washed once by re-suspension in 80 % alcohol.The washed residue was thoroughly drained on a suction filter Now at the Low Temperature Research Station, Cambridge.