1.Enantioseparation of aromatic amino acids using CEC monolith with novel chiral selector, N-methacryloyl-L-histidine methyl ester.
Aydoğan C1, Yılmaz F, Cimen D, Uzun L, Denizli A. Electrophoresis. 2013 Jul;34(13):1908-14. doi: 10.1002/elps.201200125.
A new type of polymethacrylate-based monolithic column with chiral stationary phase was prepared for the enantioseparation of aromatic amino acids, namely D,L-phenylalanine, D,L-tyrosine, and D,L-tryptophan by CEC. The monolithic column was prepared by in situ polymerization of butyl methacrylate (BMA), N-methacryloyl-L-histidine methyl ester (MAH), and ethylene dimethacrylate (EDMA) in the presence of porogens. The porogen mixture included DMF and phosphate buffer. MAH was used as a chiral selector. FTIR spectrum of the polymethacrylate-based monolith showed that MAH was incorporated into the polymeric structure via in situ polymerization. Some experimental parameters including pH, concentration of the mobile phase, and MAH concentration with regard to the chiral CEC separation were investigated. Single enantiomers and enantiomer mixtures of the amino acids were separately injected into the monolithic column. It was observed that L-enantiomers of aromatic amino acids migrated before D-enantiomers.
2.Purification of urease from jack bean (Canavalia ensiformis) with copper (II) chelated poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine methyl ester) cryogels.
Tekiner P1, Perçin I, Ergün B, Yavuz H, Aksöz E. J Mol Recognit. 2012 Nov;25(11):549-54. doi: 10.1002/jmr.2204.
Jack bean (Canavalia ensiformis) is the source of interesting proteins that contribute to modern biochemistry, and urease is the primary of these proteins. Owing to its role and occurrence in nature, urease has become a part of extensive studies. In this study, jack bean urease (JBU) was purified by immobilized metal affinity chromatography using Cu(2+) chelated poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-histidine methyl ester) [PHEMAH-Cu(2+)]-based cryogels. PHEMAH-Cu(2+) cryogel was synthesized and characterized for swelling degree, morphology (by SEM), N-methacryloyl-(L)-histidine methyl ester and Cu(2+) incorporation (by elemental analysis and atomic absorption spectrophotometry). The binding of JBU to PHEMAH-Cu(2+) cryogel was optimized by examining the effect of pH, flow rate and JBU concentration on binding. The maximal binding of JBU was 23.2 mg/dry gram of adsorbent. The maximal binding of JBU extracted from jack bean meal was 67.
3.Preparation and use of poly(hydroxyethyl methacrylate) cryogels containing L-histidine for β-casein adsorption.
Yavuz M1, Baysal Z. J Food Sci. 2013 Feb;78(2):E238-43. doi: 10.1111/1750-3841.12018. Epub 2013 Jan 17.
The objective of this study was to determine β-casein adsorption by using supermacroporous poly(2-hydroxyethyl methacrylate-N-methacryloyl-(l)-histidine methyl ester) [p(HEMA-MAH)] cryogel. β-Casein adsorption properties of p(HEMA-MAH) cryogel were studied for the application of β-casein purification. The cryogel was produced by free radical polymerization initiated by N,N,N',N'-tetramethylene diamine and ammonium persulfate pairs in an ice bath. P(HEMA-MAH) cryogel was characterized by swelling tests, Fourier transform infrared spectroscopy, and scanning electron microscopy. The effects of the flow rate, pH, temperature, initial β-casein concentration, and ionic strength on the adsorption efficiency of cryogel were studied. The equilibrium swelling degree of the p(HEMA-MAH) cryogel was 6.73 g H(2) O/g cryogel. β-Casein adsorption capacity of p(HEMA-MAH) cryogel from aqueous solution was estimated as 31.17 mg/g cryogel. It was also observed that β-casein could be repeatedly adsorbed and desorbed with p(HEMA-MAH) cryogel without significant loss in the adsorption capacity.
4.Preparation of poly(hydroxyethyl methacrylate) cryogels containing L-histidine for insulin recognition.
Çavuş A1, Baysal Z, Alkan H. Colloids Surf B Biointerfaces. 2013 Jul 1;107:84-9. doi: 10.1016/j.colsurfb.2013.01.075. Epub 2013 Feb 10.
In the present study, affinity adsorption technique was studied for insulin adsorption. Firstly, insulin-imprinted supermacroporous cryogel was prepared for the insulin adsorption. N-methacryloyl-(L)-histidine methyl ester (MAH) was chosen as the monomer. Insulin was complexed with MAH, and insulin-imprinted p(HEMA-MAH) [insulin-(MIP)] cryogel was prepared by free radical polymerization with 2-hydroxyethyl methacrylate (HEMA), N,N,N',N'-tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) in an ice bath. Then, insulin was removed from the cryogel by using 0.1 M glycine-HCl buffer (pH: 3.5). The characterization of the cryogel was carried out by using scanning electron microscopy (SEM) and swelling test. The equilibrium swelling ratios of the cryogels were found to be 8.56±0.42 g H2O/g polymer for p(HEMA) and 7.20±0.36 g H2O/g polymer for insulin-p(HEMA-MAH). Insulin adsorption experiments were performed under different conditions, such as flow rate, medium pH, initial insulin concentration and ionic strength.
