Showing papers by "Central Tuber Crops Research Institute published in 1997"
TL;DR: While the degradation of linamarin to cyanide occurs at acidic pH 5–6, the β -cyanoalanine pathway operates at alkaline pH 8–9 suggesting a compartmentalisation of these two processes.
25 citations
TL;DR: The presence of serine, an alternate substrate for the enzyme did not affect the utilisation of cysteine for the formation of β-cyanoalanine, and β-CAS from all three tissues had an optimum pH of 9.0 and showed maximum activity at 30° and the Km (cyanide) was similar.
21 citations
TL;DR: Latex linamarase was purified by ammonium sulfate fractionation and DEAE-cellulose chromatography and was characterized with respect to its amino acid composition and kinetic properties and Gel filtration and SDS-PAGE analysis showed that it was made up of a 70,000-Da peptide.
12 citations
TL;DR: In this article, the cyanogen elimination profile during cooking of cassava roots was investigated and correlated with the changes in cyanogenic β-glucosidase (GLase) activity monitored at close intervals in the cook water and root, respectively.
Abstract: The cyanogen elimination profile during cooking of cassava roots was investigated and correlated with the changes in cyanogenic β-glucosidase (GLase) activity monitored at close intervals in the cook water and root. Cyanogenic β-glucosidase (GLase) activity was detected in the cook water within 5 min of starting cooking. Whilst significant decrease in the GLase activity was noticed in cook water and root within 15 and 10 min, respectively, for varieties M4 and H165, H1687 GLase activity decreased tremendously only at 20 and 15 min in the cook water and root, respectively. There was no GLase activity in cook water after the 30 min pre-boiling phase while GLase activity was present in the roots even after 60 min of cooking. The decrease in GLase activity at 15–20 min pre-boiling phase led to accumulation of cyanogens in cook water. The cyanogen fractions (glucosidic and non-glucosidic) increased significantly with cooking in the cook water in the case of varieties M4 and H165 while their levels were almost static throughout the post-boiling phase for H1687. The amount of HCN escaping through steam did not bear a direct relationship with the initial cyanogen content in cassava roots. Although free cyanogen is highly volatile, all of it does not escape through steam and a certain quantity appears to be stabilised in the cook water. ©1997 SCI
8 citations
TL;DR: The results suggest the possible occurrence of different forms of linamarase in cassava, suggesting difference in glycosylation among leaf, rind and tuber enzymes.
Abstract: Linamarase (EC. 3.2.1.21) was purified from different tissues of cassava (leaf, rind and tuber) to compare the kinetic properties and characteristics of the enzyme in these tissues. Purified enzyme preparation appeared as single band of average molecular size 70 kD in SDS-PAGE gels. The kinetic properties of linamarase with respect to pH and temperature indicated that tuber linamarase possessed a broader pH optimum and higher temperature stability as compared to leaf and rind enzymes. Differences in Km values for linamarin were observed with leaf linamarase having the highest Km value (500 μM) followed by rind (400 μM) and then tuber (250 μM) linamarases. Rind enzyme appeared to be less susceptible to urea denaturation than the leaf enzyme. Comparison of elution profiles from DEAE-Cellulose indicated that the relative amounts of the various ionic forms of the enzyme differed in the case of each tissue. Elution patterns of the enzyme from Con A-Sepharose also differed, suggesting difference in glycosylation among leaf, rind and tuber enzymes. This was confirmed by carbohydrate analysis which showed that the tuber linamarase contained significantly higher amount of protein bound carbohydrate. These results suggest the possible occurrence of different forms of linamarase in cassava.
1 citations