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Partial characterisation of a new barley amylase
Author(s) -
NikuPaavola MarjaLeena
Publication year - 1977
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740280812
Subject(s) - amylopectin , amylase , dextrin , chemistry , maltose , amylose , starch , isoelectric point , alpha amylase , hydrolysis , enzyme , food science , hordeum vulgare , glycosidic bond , biochemistry , chromatography , biology , botany , poaceae
A new amylolytic enzyme found in barley ( Hordeum vulgare ) grain was partially characterised with respect to physicochemical properties and enzymatic activity. The enzyme preparation showed one antigenically homogeneous amylolytic band. Isoelectric focusing resolved the new amylase into two components, one isoelectric at pH 4.5, the other at pH 3.0. During focusing the original activity of the new amylase decreased by 80%. The purified preparation was inactivated by pH‐values below 4.5 and above 9.0 and also by temperatures above + 40°C for 1 h. The new amylase splits the 1,4‐α‐glycosidic linkages, clearly by endo‐attack, of starch, amylopectin, amylose and β‐limit dextrin optimally at pH 6.5 at +40°C giving K m ‐values 8.9 × 10 −3 , 4.4 × 10 −3 , 6.6 × 10 −3 and 1.7 × 10 −3 g/ml, respectively. The hydrolysis products from β‐limit dextrin were 24% glucose and 46% maltose in the total digest. Mercuric chloride, pCMB, a EDTA a and TRIS a have no noticeable effect on the new amylase, indicating that it is stable under conditions where the other amylolytic enzymes are deactivated. The new amylase seems to be a hydrolase acting on o ‐glycosyl compounds, EC 3.2.1., but could not be identified with any of the amylolytic enzymes of vegetable origin studied previously.