02971nas a2200241   4500008004100000022001400041245013500055210006900190260007300259300001200332490000700344520204800351653002602399653001302425653002702438653002502465653004102490100002102531700001602552700002002568700002302588856011802611       2007                        eng d  a0141-813000aMetal complexes of crosslinked chitosans. part II. an investigation of their hydrolysis to chitooligosaccharides using chitosanase0 aMetal complexes of crosslinked chitosans part II an investigatio  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC  a491-4960 v413 a<p>This paper investigates the behavior of crosslinked chitosans and metal-complexed crosslinked chitosans under similar hydrolytic conditions. Crosslinked chitosans with trimellitic anhydride, diisocyanatohexane, and dibromodecane as crosslinking agents under heterogenous reaction conditions were used as metal complexing agents by equilibrating them with metal salts such as ZnCl2, MnSO4, CuSO4, CdSO4, Pb(NO3)(2), and HgCl2. Crosslinked chitosan without metal complexation had the same hydrolytic behavior as uncrosslinked chitosan. However, when the crosslinked chitosans were complexed with metals, their rates of hydrolysis and extent of hydrolysis were significantly reduced. Thus, while for chitosan about 840 mu g/ml reducing sugar was produced in 4 h time, and 780 mu g/ml was produced for diisocyanatohexane crosslinked chitosan, only 400 mu g/ml and 320 [mu g/ml reducing sugars were produced for cadmium sulfate with crosslinked chitosan and diisocyanatohexane crosslinked chitosan, respectively. Similar results are obtained for other crosslinking agents. Studies on preincubation of the metal with the enzyme show that of the metals studied, Mn has no effect on preincubatioin with the enzyme, Hg, Cd, Pb, and Cu completely deactivates the enzyme, while Zn reduces the enzyme activity by about 43.3%. Preincubation of the metal salts with the chitosan shows that Hg and Cu completely deactivate the molecule from enzyme hydrolysis, Cd and Zn inactivate it to the extent of 56.8% and 43.3%, respectively, while Mn has no effect. Availability of the amino functions seems to be a key feature for the chitosanase to hydrolyze the chitosan polymer. This was also proved by the significant increase in the extent of hydrolysis for chitosan samples with 88% (final value 1120 mu g/ml reducing sugar) and 85% deacetylation (final value 840 mu g/ml reducing sugar). HPIC studies of the products show that a variety of oligomers are produced in the chitosanase enzyme hydrolytic reaction. (C) 2007 Elsevier B.V. All rights reserved.</p>10achitooligosaccharides10aChitosan10achitosanase hydrolysis10aCrosslinked chitosan10ametal-complexed crosslinked chitosan1 aTrimukhe, K., D.1 aBachate, S.1 aGokhale, D., V.1 aVarma, Anjanikumar  uhttps://library.ncl.res.in/content/metal-complexes-crosslinked-chitosans-part-ii-investigation-their-hydrolysis-001444nas a2200241   4500008004100000022001400041245013100055210006900186260007300255300001200328490000700340520057600347653001500923653001300938653001100951653001100962653001700973100002100990700002001011700002001031700002301051856012801074       2008                        eng d  a0141-813000aEnvironment friendly crosslinked chitosan as a matrix for selective adsorption and purification of lipase of aspergillus niger0 aEnvironment friendly crosslinked chitosan as a matrix for select  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC  a422-4250 v433 a<p>Chitosan and its derivatives have been used as affinity matrices for purification of lipase from Aspergillus niger NCIM 1207. Trimellitic anhydride (TMA)-crosslinked deacetylated chitin adsorbed lipase selectively, yielding approximately 5-fold purification of the crude lipase with 70% yield. Further 9-fold purification occurred on eluting through Sephacryl-100. These results suggest that chitosan derivatives can be used as inexpensive biopolymer matrices for the purification of lipases for industrial applications. (C) 2008 Elsevier B.V. All rights reserved.</p>10aAdsorption10aChitosan10aLipase10aMatrix10aPurification1 aTrimukhe, K., D.1 aMahadik, N., D.1 aGokhale, D., V.1 aVarma, Anjanikumar  uhttps://library.ncl.res.in/content/environment-friendly-crosslinked-chitosan-matrix-selective-adsorption-and-purification-0