The ability of natural and synthetic polyampholytes to exist in globular, coil, helix, stretched, and ordered conformations is reviewed and transformations and transitions between the respective states upon variation of conditions are highlighted. The properties of polyampholytes in solution, condensed, and gel state as well as at various interfaces are discussed in order to clarify the principles of the structural organization of proteins, model the function of biomembranes, and study the biocompatibility of modified materials. Application aspects of polyampholytes in protein separation, desalination, catalysis, the oil industry, biotechnology, nanotechnology, and medicine are given.
Weak polyampholytes are charged polymers, where the charge asymmetry can be tuned by varying the solution pH. We determine the size of a randomly charged weak polyampholyte in dilute solution as a function of charge asymmetry, Bjerrum length, salt concentration, pH, and degree of polymerization, using a self‐consistent method. It is known that in the limiting cases of low and high charge asymmetries, polyampholytes behave as neutral polyampholytes and polyelectrolytes, respectively. We explore in detail the regime of intermediate charge asymmetry where a polyampholyte show non‐monotonic change in the chain size as a function of Bjerrum length. A hierarchy of structures exists at different length scales, ranging from ideal coils at low Bjerrum length, extended rod‐like state at intermediate Bjerrum length to globular states at high Bjerrum length. The transition between ideal coil and rod‐like states is continuous, while that between rod‐like and globular states is discontinuous. The addition of salt changes the nature of the rod‐to‐globule transition from discontinuous to continuous. The effective free energy shows a double minimum at intermediate charge asymmetry, indicating the coexistence of globules and extended states. The size as a function of the solution pH shows a minimum at the isoelectric point. The size of neutral polyampholytes at the isoelectric pH increases with the increase in the salt concentration. The size of charge excess polyampholytes far away from the isoelectric pH decreases with the increase in the salt concentration.
Synthetic polyampholytes combining both anionically and cationically charged species have been the focus of a number of studies due to their many potential applications[1].However, there are few works that studied the polyampholytes derived from modified natural polymers. Recent work in our group has dealt with the grafting of a cationic monomer or a cationic monomer coupled with a neutral or anionic monomer onto carboxymethyl cellulose (CMC) as well as the grafting of a zwitterionic monomer onto hydroxyethyl cellulose (HEC) by using various initiation systems[2-7]. Depending on the nature of used monomers, these modified polysaccharides can carry functional acidic and basic groups of different strengths. 相似文献
High Energy Chemistry - The molecular dynamics method has been used to study the rearrangement of the conformational structure of polyampholytes adsorbed on the surface of a prolate spheroidal... 相似文献
Conclusions The optimum conditions were found for the synthesis of some new polyampholytes from a chloromethylated diphenyl oxide-formaldehyde oligomer, polyamines, and either pyridinecarboxylic acids or their nitriles, and their properties were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1652–1654, July, 1978. 相似文献
Linear and crosslinked betaine‐type polyampholytes based on ethyl 3‐aminocrotonate and unsaturated carboxylic acids have been synthesized by very fast polymerization in bulk and solution. Bulk polymerization occurred exothermically even at room temperature and without adding an initiator. The polyampholytes showed stimuli‐responsive properties with respect to pH, ionic strength, water/organic solvent mixtures, and metal ion complexation.
Temperature profile of the polymerization reaction for an equimolar mixture of CRO and AA with time in the absence of initiator. 相似文献