Synthesis and properties of polymers containing aromatic amino groups in the main chain and their glass-forming model compounds

Abstract Several model compounds containing thiol and/or amino groups (mercaptoethanol, glutathione, cysteine, ethanolamine, glycine) were studied with respect to their reactivity towards fluorescein isothiocyanate (followed spectrophotometrically at 504 and 412 nm), stability of product and long wave absorption maximum of the fluorescein residue attached. Thiol groups reacted by far more readily than amino groups. A specific effect was observed with cysteine, indicating an intramolecular transfer of the fluorescein residue from SH to NH2.With sarcoplasmic vesicles both types of reactions were observed. The ratio of products, which can be distinguished by their different stabilities and absorption spectra, depended on the absence or presence of detergents. While with native vesicles the NH2 reaction predominated, with vesicles solubilized with sodium dodecylsulfate, octaethyleneglycol mono-n-dodecyl ether or 1-0-tetradecyl-propanediol-(1,3)-3-phosphorylcholine the SH reaction became prevailing. Already 0.35 mg sodium dodecylsulfate per mg protein were sufficient to give rise to dithiourethane formation exclusively. Excess fluorescein isothiocyanate reacted with several thiol groups of dodecylsulfate-solubilized vesicles. In the presence of ATP binding of fluorescein isothiocyanate to native vesicles was significantly reduced.Total blockage of the vesicular SH groups with N-ethyl-maleimide led to preparations that reacted with fluorescein isothiocyanate much more slowly, compared to native vesicles. Octaethy leneglycol mono-n-dodecyl ether or 1-0-tetradecyl-propanediol-(1,3)-3-phosphorylcholine in the assay accelerated the thioureide formation from N-ethylmaleimide modified vesicles, whereas sodium dodecylsulfate prevented it almost completely.Our results support the suggestion that one or several thiol groups in vicinity of the highly reactive lysyl residue might play a role in the fast specific reaction, which is only observed with intact native vesicles.

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Synthesis and fluorescent properties of model compounds for conjugated polymer containing maleimide units at the main chain

Journal of Polymer Science Part A Polymer Chemistry ◽

10.1002/pola.24792 ◽

2011 ◽

Vol 49 (16) ◽

pp. 3550-3558 ◽

Cited By ~ 13

Author(s):

Kenjiro Onimura ◽

Mieko Matsushima ◽

Munetoshi Nakamura ◽

Tatsuya Tominaga ◽

Kazuhiro Yamabuki ◽

...

Keyword(s):

Conjugated Polymer ◽

Main Chain ◽

Fluorescent Properties ◽

Model Compounds

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Kinetics of the Reaction of Nitrous Acid with Model Compounds and Proteins, and the Conformational State of N-terminal Groups in the Chymotrypsin Family

Canadian Journal of Biochemistry ◽

10.1139/o72-174 ◽

1972 ◽

Vol 50 (12) ◽

pp. 1282-1296 ◽

Cited By ~ 26

Author(s):

A. Kurosky ◽

T. Hofmann

Keyword(s):

Nitrous Acid ◽

Conformational State ◽

Serine Proteinases ◽

Amino Groups ◽

Model Compounds ◽

Third Order ◽

Tyrosine Residues ◽

Reactive Groups ◽

Primary Amino ◽

Kinetics Of

The kinetics of the reaction of nitrous acid at 4° and pH 4.0 with various amino acids, peptides, and proteins were studied. The reaction with isoleucine methyl ester was found to have a linear dependence on the square of the HONO concentration showing that N2O3 was the reactive species. Third order nitrosation rate constants of primary amino groups showed a correlation with their pK values. They were calculated for the concentration of the unprotonated species to give intrinsic reactivities. The rate of nitrosation of acetyltryptophan to give N-nitrosoacetyltryptophan was found to be a linear function of the nitrous acid concentration. This nitrosation therefore follows a different mechanism. The reaction of nitrous acid with tyrosine residues was examined by spectrophotometry. The reaction was negligible compared to that of other groups. Acetylhistidine and imidazole did not react. Reactivities for α-amino groups, ε-amino groups, and other residues in proteins were compared. The conformational state of the N-terminal residues in serine proteinases, as revealed from their reactivities, is discussed in detail. It is concluded that nitrous acid reacts preferentially with "surface" residues and is a useful tool for exploring conformational states of reactive groups in proteins, especially α-amino groups and indole rings.

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Preparation and Property of Model Homogeneous ER Fluids Having Urethane Groups

International Journal of Modern Physics B ◽

10.1142/s021797929900206x ◽

1999 ◽

Vol 13 (14n16) ◽

pp. 1998-2004 ◽

Cited By ~ 4

Author(s):

Keiji Minagawa ◽

Hirokazu Okamura ◽

Seizo Masuda ◽

Masami Tanaka ◽

Naoto Gohko ◽

...

Keyword(s):

Chemical Structure ◽

Hard Segment ◽

Main Chain ◽

Model Compounds ◽

Soft Segments ◽

Er Fluids ◽

Branched Structure

Urethane modified polyether liquids composed of hard and soft segments exhibit either positive or negative ER effect depending on the structure. Here some model compounds of the urethane polymers were synthesized, and the influence of chemical structure, e.g. displacement of hard and soft segments and existence of branches, on the ER effect was studied. It was found that negative ER effect is enhanced by introducing a branched structure in the polyether main-chain or a hard segment at center of the linear polyether.

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