Glucoamylase Rhizopus niveus

Substrate Aspergillus niger glucoamylase Rhizopus niveus glucoamylase Rhizopus niveus glucoamylase - -alpha-amylose... 

Carbohydrase (Rhizopus niveus) Produced as an off white to brown, amorphous powder or a liquid by controlled fermentation using Rhizopus niveus. Soluble in water (the solution is usually light yellow to dark brown), but practically insoluble in alcohol, in chloroform, and in ether. Major active principles (1) a-amylase and (2) glucoamylase. Typical application used in the hydrolysis of starch. 

Fig, 3,—Action of Rhizopus niveus Glucoamylase (free from oIpho-Amylase)... 

Kitahara, K., Suganuma, T., and Nagahama, T. 1996. Susceptibility of amylose-lipid complexes to hydrolysis by glucoamylase from Rhizopus niveus. Cereal Chem., 73(4), 428. 

Glucoamylase from Rhizopus niveus has been shown to have an exo action on (l-> 3)-o - and (1 6)-a-D-glucan linkages as well as on malto-oligo-saccharides. ... 

In a model experiment, glucoamylase (ex Rhizopus niveus) was shown to inhibit a-D-glucan synthesis as catalysed by potato phosphorylase (see p. 498).29 ... 

The hydrolysis of maltose by glucoamylase from Rhizopus niveus was carried out in the presence an d absence of dextran sulphate, which are the components of supports of immobilized enzymes.The interaction between dextran and the enzyme was observed by fluorescence spectrophotometry. The kinetic and fluorescence experiments indicated that dextran became bound to glucoamylase and was apparently a non-competitive inhibitor of the enzyme. The dissociation constant of the enzyme-dextran complex was estimated to be 34%. The reaction rate was hardly affected at pH 4.0 and 4.5 by addition of dextran sulphate, whereas the kinetic parameters depended considerably on the concentration of dextran sulphate at pH 3.5. These findings indicated that there might exist some interactions between the enzyme and dextran sulphate. 

It was found that the aryl jS-maltotriosides were preferentially hydrolysed into maltose and aryl jS-D-glucosides by both j8-amylases. The Michaelis constant ATnj and the molecular activity ko were determined for the hydrolyses of these maltotriosides and compared with those of maltotriose and maltotetraose. Aryl jS-maltotriosides were more rapidly hydrolysed than maltotriose by a factor of 30—80, and more slowly hydrolysed than maltotetraose by a factor of 10—30, depending on the kinds of substituents. The rapid hydrolysis of aryl j3-maltotrioside as compared with maltotriose was considered due to the interaction of an aryl group with the subsite of j8-amylase. This is in contrast with Rhizopus niveus glucoamylase-catalysed hydrolysis of phenyl j8-maltoside, whose phenyl group does not interact so much with the subsite of the enzyme. 

Reduction and carboxymethylation of A. niger glucoamylase resulted in complete loss of enzymic activity, whereas O-acetylation of three of the 13 tyrosyl residues resulted in loss of 20% of the enzymic activity. The tryptophanyl residues of Rhizopus niveus glucoamylase have been modified by treatment with A-bromosuccinimide so that the subsite structure of the enzyme could be studied. ... 

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