Studies on Chitin IX. Specific Binding of Calcium Ions by Carboxymethyl-Chitin

Abstract

Carboxymethylation of chitin was carried out effectively for preparing a cation exchange resin under basic conditions. The resulting carboxymethyl-chitin (CM-chitin) was found to bind calcium ions specifically among alkali-earth metals even in the presence of monovalent cations such as sodium or potassium. Differential IR absorption spectroscopy suggested that the binding of calcium ion by carboxyl groups was assisted by acetamide groups at C2 and primary hydroxyl groups at C6 or secondary hydroxyl groups at C3 in the N-acetylglucosamine residue. The binding constants were estimated at various ionic strengths and ion concentrations. The selectivity coefficient of CM-chitin for calcium ions over sodium ions was assumed to be 45.6 at neutral pH and 0.1-{).2 of ionic strength. The fibrous CM-chitin was prepared to investigate the effects of an increase in the number of surface ionic sites and degree of orientation on the binding capacity. The results indicated a marked enhancement.

Minimizing acylation of peptides in PLGA microspheres

“…CMCS is known to have good chelating affinity with metals [38]. Mn 2+ mainly binds to the carboxymethyl groups of CMCS [39], whereas chelation of the biopolymer with Ca 2+ is assisted by the acetamide and hydroxyl groups in addition to carboxyl groups [40]. This chelation ability might be helpful to prevent the peptide sorption competitor, divalent cations, from leaking from degrading PLGA microspheres.…”

Improved Anti‐Inflammatory and Pharmacokinetic Properties for Superoxide Dismutase by Chemical Glycosidation with Carboxymethylchitin

“…The remarkable resistance against H 2 O 2 conferred to SOD by glycosidation with CHCH could be mediated by the chelating ability of the polymer,32 which could bind the Cu 2+ released from the protein structure after H 2 O 2 oxidation. Through this chelating mechanism, the further occurrence of Fenton‐type reactions could be avoided, preserving the active enzyme molecules from radical oxidation with highly toxic substances.…”

Improved Pharmacokinetics Properties for Catalase by Site‐Specific Glycosidation with Aminated Dextran

“…Endogenous catalase activity was previously evaluated in each animal before enzyme inoculation. The plasma level of all enzyme forms as a function of time was analyzed by a twocompartment model, fitting the experimental data to the equation C(t) ¼ Ae Àat þ Be Àbt , [19,20] and assuming the initial enzymatic activity determined in the blood plasma after intravenous (i.v.) administration as 100%.…”