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Articles by Ranajit Kumar Shaha
Total Records ( 3 ) for Ranajit Kumar Shaha
  Ranajit Kumar Shaha , N. K. Sana and M. Rezaul Karim
  In the cotyledons of germinating Lentil (Lens esculenta L.) at 15 days the abundant amylolytic activity was found to be β-amylase (E.C., α-1-4-glucan maltohydrolase). β-amylase from germinating Lentil cotyledons was purified to homogeneity for study of enzyme characteristics. The purification steps included ammonium sulphate precipitation followed by DEAE-cellulose chromatography and hydroxylapatite chromatography. By successive steps of (NH4)2 SO4 fractionation, DEAE-cellulose chromatography and HA filtration, the purity of the enzyme from lentil increased 108.5 fold with an overall yield of 32.2% with specific activity of 575 U mg-1. The end product of -1, 4-glucan degradation was maltose. The β-amylase was most active at pH 6.1 (soluble starch substrate) and 40°C. Km for Lentil cotyledons β-amylase for soluble potato starch was 1.67 milligrams per milliter (mg ml-1). The molecular weight of the enzyme was estimated to be 58 kilodaltons (kDa) by both gel filtration and sodium dodecyl sulphate gel electrophoresis. Heavy-metal ions Cu2+, Hg2+ and Ag+ at 1.0 mM concentration and p-hydroxymercuribenzoic acid and N-bromosuccinimide at 0.4 mM concentration inhibited the enzyme activity. Lentil β-amylase is competitively inhibited by its end product, maltose, with a Ki of 8.4 mM. Less branched or no-branched (amyloses) were better substrates for Lentil cotyledons β-amylase than moderately branched glucans ( amylopectin) or highly branched (glycogens) glucans.
  M. Omar Faruk , M. Ziaul Amin , Niranjan Kumar Sana , Ranajit Kumar Shaha and Kamal Krishna Biswas
  In this study, two varieties (Green and red) of water chestnuts (Trapa sp.) have been selected for their biochemical analysis as well as nutrient composition using standard methods. The proximate composition of green water chestnuts revealed moisture 62.5, ash 1.04, crude fiber 2.13%, total soluble sugar 0.92%, reducing sugar 0.33%, non-reducing sugar 0.59%, starch 8.7%, lipid 0.84%. One hundred gram of green variety contained water soluble protein 0.275 mg, β-Carotene 60 μg, vitamin-C 1.1 mg and total phenol 0.5 mg. The minerals contents of green variety were potassium 5.22%, sodium 0.64%, calcium 0.25%, phosphorus 6.77%, sulpher 0.38%, and iron, copper, manganese and zinc 200, 430, 90 and 600 ppm, respectively. The red variety contained moisture 62.7%, ash 1.30%, crude fiber 2.27%, total soluble sugar 0.90%, reducing sugar 0.30%, non-reducing sugar 0.60%, starch 8.2%, lipid 0.83%. The red variety contained water soluble protein 0.251 mg, β-Carotene 92 μg, vitamin-C 0.9 mg and total phenol 0.60 mg per 100 g. The red variety contained potassium 5.32%, sodium 0.59%, calcium 0.26% phosphorus 6.77%, sulpher 0.32%, Iron 200 ppm, copper 450 ppm, manganese 110 ppm and zinc 650 ppm. The free amino acids, glutamic acid, tryptophan, tyrosine, alanine, lysine and leucine were commonly found in both varieties. In addition, green and red variety contained cysteine, arginine and proline and glutamine and asparagines, respectively. Thus, the present study sheds light on the nutrient contents of the two varieties of water chestnuts and suggests that water chestnuts may play a crucial role in human nutrition.
  Ranajit Kumar Shaha , N.K. Sana , N. Roy , K.K. Biswas and Abdullah Mamun
  Enzyme with proteolytic activity was found in the germinating wheat seeds (Triticum aestivum L.,). The enzyme activity appeared after 40 h of dark germination and reached its maximum value after 72 h and then declined sharply during further germination. After ion exchange chromatography, three protein peaks ( pro-I, pro-II & pro-III ) showed proteolytic activity and the degree of purification attained nearly 29-42 fold. Properties like optimum pH and optimum temperature of pro-I, pro-II and pro-III were 7.1, 6.4, 6.8 and 45°C, 43°C and 42°C, respectively. Mg2+ and Mn2+ had no effect on enzyme activities while EDTA, urea, Ca2+ had an activating effect. On the other hand Hg2+ and Fe2+ had strong inhibitory action on the extracted enzyme. The enzymes were found to be homogeneous as judged by Polyacrylamide disc gel electrophoresis. Molecular weights of pro-I, pro-II and pro-III were 1.08, 1.04 and 99kD and Km values were found to be 0.027, 0.032 and 0.037 mM respectively.
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