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Articles by N. Absar
Total Records ( 8 ) for N. Absar
  F. Pervin , M.M. Hossain , S. Khatun , S.P. Siddique , K.A. Salam , M.R. Karim and N. Absar
  Six bioactive lectins were purified from the rootstock of Pondweeds (Potamogeton nodosus Poir) by conventional chromatographic methods. They showed cytotoxic effect in brine shrimp (Artemia salina L.) lethality bioassay. The LD-50 values of PNL-1, PNL-2, PNL-3, PNL-4, PNL-5 and PNL-6 were found to be 10.76, 7.03, 17.25, 10.52, 19.60 and 20.1 μg mL-1, respectively which implied that they have significant uses specially of PNL-2. Experimental results revealed that PNL-2 and PNL-4 were more cytotoxic than other lectins.
  M.R. Karim , M.A. Islam , N. Absar and F. Hashinaga
  A protease from tomato flesh was purified to homogeneity by (NH4)2SO4 precipitation followed by Sephadex G-75 and DEAE-cellulose column chromatography. Molecular weight of the enzyme was estimated to be 81-79 KD by gel filtration and SDS-PAGE respectively. The enzyme was found to be a single polypeptide chain as revealed by SDS-PAGE under either reducing or non-reducing conditions. Optimum activity was observed at pH 7.0 and 45°C with a km value of 0.48 per cent determined by using casein as substrate. The enzyme appears to be a serine protease being inhibited greatly by DFP and PMSF and to a lesser extent by heavy metals such as Pb2+ and Fe2+.
  M.Z. Rahman , Z.A. Saud , N. Absar , M.R. Karim and F. Hashinaga
  Two different amylase from the flesh of healthy and fruit-rot disease-affected Moringa fruit were purified by successive chromatography of the crude enzyme extract on DEAE-cellulose followed by CM-cellulose and were purified 46- and 50-fold respectively. Both the enzymes appeared to be homogeneous as judged by polyacrylamide gel electrophoresis. Molecular weights of amylases from healthy and diseased Moringa estimated by gel filtration were 59 kDa and 66.5 kDa respectively. The purified enzymes were classified as -amylase and consist of a single polypeptide chain. The amylase from healthy and diseased Moringa flesh showed the following characteristics: pH optima, 6.8 and 6.4; temperature optima, 38 °C and 40 °C; Km value, 0.28 and 0.22% for starch as substrate respectively.
  M.A. Hossain , S.M. Rafiqul Islam and N. Absar
  Three electrophoretically homogeneous lectins were purified from the extract of mulberry seeds. The two lectins i.e. MSL-2 and MLS-3 were purified by gel filtration of 100% ammonium sulfate saturated crude extract followed by ion-exchange chromatography on DEAE-cellulose while another MSL-1 was purified by further chromatography on CM-cellulose column. The purity of the lectins was checked by polyacrylamide disc gel electrophoresis. The molecular masses of MSL-1, MSL-2 and MLS-3 as determined by gel filtration were estimated to be 175, 120 and 89 kDa, respectively. Again molecular masses of MSL-1, MSL-2 and MSL-3 as determined by SDS-polyacrylamide gel electrophoresis were calculated to be 177, 121 and 90 kDa, respectively. SDS-polyacrylamide gel electrophoresis indicated that the lectin, MSL-1 was dimer in nature with two subunits held together by disulfide bonds. The other two lectins, MSL-2 and MSL-3 were tetramer in nature contained four non-identical subunits that were held together by nonionic hydrophobic interaction. The lectins agglutinated specifically rat red blood cells and galactose and galactose containing sugars were found to be the potent inhibitor of agglutination. The lectins were glycoproteins in nature with neutral sugar content of 5.6, 5.3 and 4.5% for MSl-1 MSL-2 and MSL-3, respectively. The sugar composition of the lectins was glucose and mannose for MSL-1 and galactose for both MSL-2 and MSL-3.
  Md. Abul Kashem Tang , K.A. Salam , M.A. Samad and N. Absar
  The nutritional composition such as moisture, ash, lipid, protein, carbohydrate, total chlorophyll, crude fibre, phenol, β-carotene, vitamin-B1, vitamin-B2, vitamin-C, Ca, P and Fe contents of four varieties of healthy and disease infected mulberry leaves at mature stage were analyzed. The mulberry leaves are considered as good source of starch, protein, crude fibre, minerals, vitamin-C and β-carotene and their contents in healthy leaves were found to be about 6-7, 4.0-4.6, 3.0, 3.0-3.5%, 115-132 and 100-120 mg%, respectively. Of the nutrients analyzed, dry matter, ash, lipid, crude fibre, carbohydrate and mineral contents were decreased but moisture, protein and phenol contents were increased after infection of fresh healthy mulberry leaves with fungus.
  K.A. Salam , A.K.M. Motahar Hossain , A.H.M. Khurshid Alam , F. Pervin and N. Absar
  The physico-chemical characteristics °of oils extracted from six different parts of hilsa °fish (Hilsa ilisha) like dorsal, ventral, tail, egg, liver and brain were analyzed. The physical characteristics such as the specific gravity, refractive index, smoke point, flash point, fire point, cloud point, solidification point and pour point of the hilsa fish oils from the different parts presently examined were ranged from 0.920 to 0.932, 1.4700 to 1.4722 at 25°C, 220 to 228°C, 322 to 330°C, 350 to 364°C, 2 to 2.4°C, -10 to -5°C and -7 to 6°C, respectively. The chemical properties such as saponification value, iodine value, peroxide value, acid value, % FFAs and unsaponifiable matters of the hilsa fish oils from different parts were found to be varied from 180.28 to 194.00, 80.70 to 126.40, 7 to 10, 4.16 to 12.00, 2.08 to 6.00 and 1.58 to 7.00%, respectively. The saturated and unsaturated fatty acids present in the oil samples were mainly myristic acid (5.44 to 7.24%), palmitic acid (22.00 to 27.08%), stearic acid (4.00 to 6.32%), palmitolenic acid (12 to 14%), oleic acid (26.08 to 29.78%), linoleic acid (0.92 to 2.20%) and linolenic acid (0.82 to 1.08%). The storage effect on the hilsa fish oils, which were obtained from different parts for the production of fatty acids by the action of lipase have been studied after storing the samples at low temperature (-10 to 0°C) and at room temperature (25 to 28°C). The contents of % FFA were initially low but increased rapidly on storage. It has been shown that lipase enzyme in hilsa fish oil is active even at temperature -10°C. The hydrolytic deterioration of hilsa fish oils were found to be more effective at 0°C than that from -10°C. Further, the qualities of hilsa fish oils were deteriorated slightly further when stored at 25°C.
  Luthfunnesa Bari , Parvez Hassan , N. Absar , M.E. Haque , M.I.I.E. Khuda , M.M. Pervin , Shahanaz Khatun and M.I. Hossain
  Two varieties, Local-1 and Local-2 of papaya (Carica papaya L.) were analyzed at four maturity stages (green, mature, ripen and rotten) to obtain a comparative information on their nutritional parameters such as pH, moisture, ash, TTA protein, lipid, carbohydrate, free sugar, reducing sugar, carotene, riboflavin, thiamin, ascorbic acid, calcium, sodium, magnesium, potassium, iron and phosphorus content. The nutrient composition of papaya flesh was found to vary at different maturation stage. The pH, moisture content increases gradually with advancement of maturity in healthy papaya but decreases at rotten stage. The ash, TTA and fiber content was found to be maximum in mature stages and gradually deceases from ripen stage to rotten stage. The results on carbohydrate shown that ripe papaya is a good source of carbohydrate (23.5±0.04 g %) but the content decreases in rotten stage. The concentration of protein, lipid, riboflavin and thiamine are extremely low in ripe papaya. The free sugar, reducing sugar and starch content gradually increases up to ripen stage but decreases at rotten stage. Ripe papaya is a very rich source of vitamin A and vitamin C but their concentrations decrease abruptly at rotten stage. The minerals such as calcium, sodium, magnesium, potassium and phosphorus content of papaya flesh gradually increases with the advancement of maturity whereas the increasing level of iron declines at ripen stages.
  M.A. Hossain , M.T. Hossain and N. Absar
  The lectin, MSL-1 was subjected to various chemical modifications in order to ascertain the amino acid residues responsible for their hemagglutinating activity. Modification of MSL-1 with acetic anhydride blocked nineteen amino groups and five tyrosine residues per molecule of lectin and decreased complete hemagglutinating activity. De-O-acetylation regenerated four of the tyrosine residues and resulted in a recovery of 80% activity. The presence of inhibitory saccharide galactose, a significant protecting effect was observed and only 1.49 tyrosine residues and fifteen amino groups were found to be modified with significant retention of hemagglutinating activity. The treatment of lectin with citraconic anhydride showed that nineteen amino were modified with the loss of 25-30% hemagglutinating activity. Modification of lectin with N-acetyl imidazole resulted in acetylation of fifteen amino groups and six tyrosine residues per molecule. De-O-actylation also regenerated 4.5 tyrosine residues with the retention of 75% of its hemagglutinating activity. When modification was conducted in the presence of galactose, about 3.5 tyrosine residues were protected from modification with 80% hemagglutinating activity. Successive addition of NBS to MSL-1 solution resulted in the modification of five tryptophan residues per molecule of lectin at pH 6, 5 and 4, respectively with the loss of 20-30% hemagglutinating activity. With DEPC at pH 7.2, eight histidine residues were modified and in the presence of inhibitory saccharide galactose, five histidine residues were protected from modification with the retention of 90% hemagglutinating activity. This was further confirmed from the finding that the activity was regenerated when His-modified MSL-1 was treated with hydroxylamine. The overall modification studies indicated that four tyrosine and five histidine residues were located at the saccharide-binding site of the lectin. However, modification of tryptophan and lysine had no effect on the hemagglutinating activity.
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