Inhibitory Effects of Cyanide on the Activity of Granular Starch Hydrolyzing Enzyme (GSHE) during Hydrolysis of Cassava (Manihot Esculenta Crantz) Starch

  • Hargono Hargono Department of Chemical Engineering, Faculty of Engineering, Diponegoro University, Prof. H. Soedarto, SH Road-Semarang, Indonesia
  • Andri Cahyo Kumoro Department of Chemical Engineering, Faculty of Engineering, Diponegoro University, Prof. H. Soedarto, SH Road-Semarang, Indonesia
  • Bakti Jos Department of Chemical Engineering, Faculty of Engineering, Diponegoro University, Prof. H. Soedarto, SH Road-Semarang, Indonesia

Abstract

The kinetics and inhibitory effects of cyanide on the granular starch hydrolyzing enzyme (GSHE) activity during hydrolysis of cassava (Manihot esculenta Crantz) starch at low temperature were studied. The substrates included native cassava starch at various concentrations (100-400 g/L) and native cassava starches with added cyanide at various concentrations (50-150 mg/kg), while the concentration of enzyme was 1.5% (w/w). A decrease in reducing sugar concentration during hydrolysis of cassava starch indicated that the cyanide reduced the enzyme activity. Lineweaver-Burk plot of Michaelis-Menten equation was used to study the inhibition kinetics. The maximum velocity (Vmax) value was higher for native cassava starch than that of native cassava starch with added cyanides. The presence of cyanide was found to reduce the Vmax values. No significant different of the saturation constant (Km) value between native cassava starch and native cassava starch with added cyanides was observed. Based on the inhibition type analysis, the effect of cyanide in the cassava starch can be classified as a noncompetitive inhibition, with the Ki value of 0.33 mg/L.

Keywords: cyanides, inhibitory, enzyme activity, kinetics, hydrolysis
Published online
2018-05-16
How to Cite
Hargono, H., Kumoro, A. and Jos, B. (2019) “Inhibitory Effects of Cyanide on the Activity of Granular Starch Hydrolyzing Enzyme (GSHE) during Hydrolysis of Cassava (Manihot Esculenta Crantz) Starch”, Periodica Polytechnica Chemical Engineering, 63(1), pp. 11-17. doi: https://doi.org/10.3311/PPch.12006.
Section
Articles