ENZYMATISCHE MODIFIZIERUNG VON ENZYMEN GLUCOAMYLASE ALS BEISPIEL AUS DER STÄRKEVERARBEITUNG

Abstract

The chemical modification of microbial enzymes has gained increased importance. A controlled enzymatic treatment of biocatalysts can be another step towards "taylor-made" enzymes for use in food industry. The transformation of starch containing raw materials in maltose, glucose and fructose are established processes. Anyhow, it will be shown in this presentation, how a specific modification of ASPERGILLUS NIGER-Glucoamylases can lead to interesting properties in the application of industrial saccharification. During the late stage of the submerse production of glucoamylase from ASPERGILLUS NIGER, a proteolytic modification of the enzyme molecule happens. The formed enzyme shows a slightly different substrate specificity than the original enzyme. The properties of the purified glucoamylase- isoenzymes are demonstrated by means of degradation trials with branched and linear oligosaccharides. Isomaltose is formed as the main product of the reverse action from glucose as substrate by both isoenzymes. Both glucoamylases are able to split alpha-1-6-glucosidic bonds of maltooligosaccharides. The practical importance and possible influences of a certain isoenzyme ratio of commercial glucoamylases are explained with comparative saccharification trials using enzymatically liquefied wheat starch as substrate.