Stability of alpha-amylase immobilized on poly(methyl methacrylate-acrylic acid) microspheres

Aksoy, S
Tumturk, H
Hasırcı, Nesrin
Poly(methyl methacrylate-acrylic acid) microspheres were prepared and the acid groups were activated by using either carbodiimide (CDI) or thionyl chloride (SOCl2). alpha-Amylase was covalently bound on these activated microspheres. The properties of the immobilized enzyme vv ere investigated and compared with those of the free enzyme. The relative activities were found to be 80.4 and 67.5% for carbodiimide and thionyl chloride bound enzymes, respectively. Maximum activities were obtained at lower pHs and higher temperatures upon immobilization compared to free enzyme. No change in V-max and approximately 12-fold increase in K-m,were observed for immobilized enzymes. The enzyme activities, after storage for 1 month, were found to be 24.5 and 52.5% of I:he initial activity values for CDI and SOCl2, activated matrices, respectively. On the other-hand the free enzyme lost its activity completely in 20 days. Immobilization, storage stability and repeated use capability experiments carried out in the presence of Ca2+ ions demonstrated higher stability, such as SOCl2,immobilized enzyme retained 83.7% and CDI immobilized enzyme retained 90.3% of the original activity of the enzyme. Thf immobilized enzymes that were used 20 times in 3 days in repeated batch experiments demonstrated that, in the absence of Ca2+ ions about 75% and in the presence of Ca2+ ions greater than 90% of the original enzyme activity was retained.


Activation of poly(dimer acid-co-alkyl polyamine) particles for covalent immobilization of alpha-amylase
Hasırcı, Nesrin; Tumturk, Hayrettin (2006-12-01)
Poly(dimer acid-co-alkyl polyamine) particles were activated by using various chemicals such as carbodiimide (CDI), ethylene diamine (EDA), and hexamethylene diamine (HMDA) and studied as support materials for covalent immobilization of alpha-amylase. The activities of the immobilized enzymes on these activated particles were investigated. The highest activity of free enzyme was obtained at pH 7.5 while this value was shifted to pH 6.5 for CDI and EDA activated systems and to pH 8.0 for HMDA activated syste...
Synthesis, characterization and electrochromic properties of copolymer of terephthalic acid bis-(thiophen-3-yl-methyl) thioester with thiophene
Turkarslan, O; Erden, A; Sahin, E; Toppare, Levent Kamil (Informa UK Limited, 2006-01-01)
Terephthalic acid bis-(thiophen-3-yl-methyl thioester) (TTMT) was synthesized via the reaction of thiophen-3-yl methanethiol with terephthaloyl dichloride. Nuclear magnetic resonance ( H-1-NMR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy were utilized for the characterization of the monomer. Electrochemical copolymerization of TTMT with thiophene in acetonitrile/boron trifluoride diethyl etherate (AN/BFEE) (8:2, v/v) solvent mixture was realized by using tetrabutylammonium tetrafluorobor...
Unusual manganese(III)-mediated oxidative free-radical additions of Meldrum's acid and dimethyl malonate to benzonorbornadiene and oxabenzonorbornadiene
ÇALIŞKAN, Raşit; Nohut, Neslihan; Yilimaz, Ozlem; ŞAHİN, Ertan; Balcı, Metin (Elsevier BV, 2017-01-26)
Benzonorbornadiene and 7-oxabenzonorbornadiene were reacted with Meldrum's acid and dimethyl malonate in the presence of Mn(OAc)(3) and Cu(OAc)(2) in acetic acid. The reaction of benzonorbornadiene with Meldrum's acid gave a naphthalene derivative whereas the reaction with dimethyl malonate formed rearranged products derived from a carbocation intermediate. However, the reaction of 7-oxabenzonorbornadiene with Meldrum's acid gave two nonrearranged products. On the other hand, the reaction with dimethyl malo...
DEMIR, AS; AKGUN, H; Tanyeli, Cihangir; SAYRAC, T; WATT, DS (1991-09-01)
The alpha'-chloroacetoxylation of alpha,-beta-unsaturated ketones using manganese(III) acetate and chloroacetic acid followed by Arbuzov reaction and intramolecular Horner-Emmons olefination provided a convenient synthesis of annulated 2-buten-4-olides.
Effects of aromatic diboronic acid on thermal charateristics of polybenzoxazines based on phenol and aniline
Telli, Aysegul Hisar; Hacaloğlu, Jale (2018-11-01)
In this work, polybenzoxazines based on phenol and aniline were prepared by curing as-synthesized and purified monomers in the presence of aromatic diboronic acid, BDBA. Condensation reactions between BOH groups of diboronic acid and phenolic OH groups of benzoxazine took place during curing only when unreacted phenol, or low mass oligomers were present in the medium. Generation of fragments involving B-O-C groups and significant improvement in thermal characteristics were detected upon curing the as-synthe...
Citation Formats
S. Aksoy, H. Tumturk, and N. Hasırcı, “Stability of alpha-amylase immobilized on poly(methyl methacrylate-acrylic acid) microspheres,” JOURNAL OF BIOTECHNOLOGY, pp. 37–46, 1998, Accessed: 00, 2020. [Online]. Available: