Reaktive copolymere des N-vinyl-2-pyrrolidons zur immobilisierung von enzymen

1-Vinyl-2-pyrrolidone was copolymerized with maleic acid anhydride, with acrylic acid, and with tyrene respectively, using 1,4-divinylbenzene as crosslinking agent. By polymeranalogous reactions isothiocyanato- and diazo groups were introduced into the styrene copolymers, respectively, and azido groups into the acrylic acid copolymers. These reactive, insoluble, hydrophilic carriers were used for the immobilization of enzymes by covalent binding. The copolymers, particularly their ability to immobilize papain as well as their enzymatic activity, were investigated.     

Reaktionsfähige hochpolymere auf polystyrolbasis als träger von proteinen und enzymen

Reactive, hydrophilic, insoluble polymers which contain nitrofluorobenzenesulfonyl groups were prepared by FRIEDEL -CRAFTS reaction of 4-fluorobenzenesulfonyl chloride with polystyrene and subsequent sulfonation and nitration. Reactive, hydrophilic, insoluble polymers containing dinitrofluorophenyl groups were prepared by nitration of copolymers obtained from 4- or 3-fluorostyrene, methacrylic acid, and divinylbenzene. The chemical reactivity of these polymers especially their ability to bind proteins were investigated. The reaction of these polymers with diastase and papain gave enzyme resins; their properties were investigated.     

Reaktive Träger auf der Basis von Polyethylenimin zur Immobilisierung von Enzymen

Reactive slightly basic carriers with isothiocyanato and azido groups, which are able to bind enzymes covalently, could be obtained by reaction of crosslinked and uncrosslinked poly-(ethyleneimine) with 4-nitrophenyl isothiocyanate, 4-nitrophenyl isocyanate, or ethyl chloroacetate, respectively, and subsequent reactions. The binding ability of the carriers for papain, trypsin, α-chymotrypsin, and urease in dependence of the content of reactive groups and in the case of urease as function of the amount of offered enzyme was investigated. To characterize the immobilized enzymes some properties as enzymatic activity, storage stability, and stability after repeated application were determined.     

Über poly[1-N-(4-isothiocyanatophenyl)carbamoyloxy-methyläthylen-co-1-hydroxymethyläthylen]e als träger zur immobilisierung von papain

Poly[1-N-(4-isothiocyanatophenyl)carbamoyloxymethylethylene-co-1-hydroxymethylethylene]s ( 5a – c ) were obtained by reaction of poly(allyl alcohol) ( 2 ) with 4-isothiocyanatophenyl isocyanate ( 3 ). In some cases 1,4-phenylenediisocyanate ( 4 ) was used as crosslinking agent. These reactive carriers were found to be suitable to immobilize enzymes by covalent bonds. The binding abilities of these polymers 5a – e for butylamine, 3,4-dichloroaniline, peptone (from lactalbumin), and papain were investigated. The enzymatic activity, the pH-optimum, the apparent Michaelis-constant K_M(app), and the activity dependance on temperature were determined for the immobilized papain.     

Festphasensynthese von oligonucleotiden, 11. Verwendung eines neuartigen hydrophilen perlpolymerisats als träger

New hydrophilic swellable and lowly crosslinked bead copolymers consisting of dimethylaminocarbonylethylene or -propylene and alkoxycarbonylethylene or -propylene repeating units were prepared starting from activated esters of acrylic acid ( 8a–10a ) or methacrylic esters ( 8b–10b ) and N,N-dimethylacrylamide ( 12a ). This “hydrophylic Merrifield carriers” were applied for polymer-supported oligodeoxynucleotide syntheses. They were found to be swellable in a wide range of solvents. The first deoxynucleoside was attached to the carrier via its 5′-hydroxyl group by an ester bond. The cleavage of the bond between carrier and oligonucleotide was performed with aqueous sodium hydroxide under conditions which do not attack the N-protecting groups attached to the oligonucleotide chain. The acid labile 1-ethoxyethyl group was used as 3′-protecting group for the phosphate component (N-protected deoxynucleoside-5′-phosphate). Some suitable protected deoxynucleosides were synthesized for anchoring and deoxynucleoside-5′-phosphates for chain elongation. In a condensation reaction according to the diester method, a dinucleoside monophosphate ( 7 ) was prepared and, as a consequence of the flexibility of the polymeric backbone, the synthesis of longer oligonucleotides should be feasible. The alkali labile anchoring of the oligonucleotides to the carrier can allow to avoid wrong sequences by simple acylation of the non-reacted 3′-OH groups with acetic anhydride after each condensation step.     

Chemische synthese verzweigter polysaccharide, 5. Kopplung von oligosacchariden und amylose an verschiedene träger durch hydrazonbindung

The coupling of glucose and maltooligomers by hydrazone linkage to carriers by means of acid hydrazide groups was investigated. The following carriers were used: (1) linear polymers such as (a) poly(ethylene glycol) with carboxymethyl (CM) end groups, (b) CM-amylose and CM-cellulose, 6-COOH amylose and 6-COOH cellulose, pectic acid, alginic acid, poly(acrylic acid); (2) multifunctional centers such as (c) CM-cyclodextrin, 1,3,5-benzenetricarboxylic acid, 1,3,4,5-benzenetetracarboxylic acid, crosslinked poly(acrylamide) (BIO-GEL). The hydrazone linkage which is formed preferably in borate buffer at pH 8,5 was stable above pH 6 and could be split by mild acid treatment at pH 4. Maltooligomeric grafts of degree of polymerization DP ≧ 4 may be extended enzymatically by phosphorolytic synthesis to amylose chains of variable length. Primer activity of the bound maltooligomers for phosphorylase was obviously not hindered by the hydrazone linkage, by free hydrazide groups, or by synthetic polymers as carriers. ABA-Block copolymers may be derived from(a), comb-like molecules from (b), and different kinds of star-like molecules from (c).     

Über einige Copolyurethane ausgehend von Piperazin

Bis(2-hydroxyethyl) piperazine-1,4-dicarboxylate ( 3 ) was prepared by addition of ethylene carbonate to piperazine (mole ratio 2:1). The reaction of 3 with aliphatic or aromatic dicarboxylic acid chlorides yielded alternating polyesterurethanes 5 and 7 . The sequenced copolyurethane 8 was obtained by polyaddition of 3 and 4,4′-methylene bis(phenylisocyanate). Interfacial polycondensation of the bis(chloroformyl) derivative of 3 with aliphatic and aromatic diamines afforded ordered copolyurethanes of type 11 .     

Reaktive mikrogele, 4. Über besonderheiten bei der emulsionspolymerisation von 1,4-divinylbenzol

The emulsion polymerization of 1,4-divinylbenzene with sodium dodecylsulfate as emulsifier and potassium persulfate as initiator was studied to obtain reactive microgels with different sizes. Comparing the results of the emulsion polymerization of 1,4-divinylbenzene with that of styrene specific differences were found as formation of coagulum, several agglomeration stages, and considerably higher numbers of particles in case of 1,4-divinylbenzene. The possible reasons for these characteristic differences are discussed.     

Handelsübliche polymere als träger in der oligonucleotidsynthese, 1. Synthese eines pentanucleosidtetraphosphats an merckogel or 1000 000®

Merckogel OR 1000000®, a commercial macroreticular polyvinylacetate resin, was partially saponified and loaded with nucleoside (0,5 mmol/g) by reaction with 3′-O-(β-benzoylpropionyl)-5′-thymidyl chloroformate. The synthesis of oligonucleotides on this carrier was done in three steps per chain extension, namely 1. the phosphorylation of the 3′-OH groups with β-cyanoethyl phosphate, 2. the condensation with 3′-O-(β-benzoylpropionyl)thymidine, and 3. cleavage of the benzoylpropionyl groups. Steps 1 and 3 occurred almost quantitatively and step 2 in ca. 50% yield. The reaction cycle was gone through four times and, thus, the pentanucleoside tetraphosphate dT (pT)₄ ( 11 ) was synthesized in 6% overall yield. A device for the micromanipulation of support resins is described.     

Untersuchungen zur irreversibilität von Netzwerkentschlaufungen beim Fließen von Polymerschmelzen

Experimental and theoretical investigations of stress relaxation after “double-step” shear experiments lead to a better understanding of the irreversibility assumption of polymer melts. Here we compare measurements of shear stress relaxation for a branched polyethylene and a (linear) polyisobutene melt to theoretical predictions of Wagner's first and second equation and to a molecular theory of Doi. None of these theories is able to describe all the results of the measurements. These investigations demonstrate, however, what types of “double-step” shear experiments are most sensitive to the irreversible disentanglement of polymer melts.     

Neuere Erkenntnisse zur Polymerisation von Blausäure

Two principally different mechanisms are discussed for the polymerisation of hydrogen cyanide. The one considers the building up of the polymer as being stepwise and based on hydrogen cyanide as the monomer, whereas the other one assigns the hydrogen cyanide dimer for being the actually polymerizing “monomer”. In the case of the “dimer polymerisation” a carbene mechanism is taken into consideration besides an anionic one. Different N-alkyl substituted hydrogen cyanide dimers were synthesized. They did not exhibit any properties of a carbene and were relatively stable. Their reactions with hydrogen cyanide were studied. A series of addition products were obtained which extensively favor the mechanism of the stepwise polymerisation.     

Kinetik der anionischen Polymerisation von Styrol in Dioxan mit Polystyryl-Natrium als Reaktionträger

The propagation rate constants of the anionic polymerization of styrene in dioxane were measured as a function of the “living” end concentration and of the temperature. They were compared with corresponding values in other solvents. It is shown that only contact ion-pairs are involved in this polymerization.     

Reaktive mikrogele, 8. Anionische polymerisation von ethylendimethacrylat

By polymerisation of ethylene dimethacrylate with n-butyllithium in solution reactive microgels have been obtained. These EDMA-microgels are nearly spherical, have a broad distribution and are easily swellable in organic solvents. The macrogelation depends on the amount of solvent between the microgel particles.     

Kinetische untersuchungen zur reaktionsfähighkeit von chlormethylgruppen in methylendiphenolen

The chloromethyl derivatives of 16 differently substituted methylenediphenols were synthesized for the first time. To compare their reactivity, the solvolysis in methanol and the animolysis with an excess of p-nitroaniline in dimethyl sulfoxide were studied kinetically at 25°C. The rate constants for the methanolysis do not differ very much, beside of the fact that para-chloromethyl derivatives react about 100 times faster than ortho-chloromethyl derivatives. However, for the aminolysis a large acceleration up to 10³ was found for compounds having both hydroxyl groups in ortho-position to the methylene bridge. Obviously, the cleavage of the O? H bond, which occurs in the rate determining step of the aminolysis, is strongly favoured by an intramolecular hydrogen bond between the phenolic hydroxyl groups.     

Beitrag zur bestimmung von hydroxylzahlen in ungesättigten polyesterharzen

Some methods for determining the hydroxyl number were tested for their applicability to unsaturated polyester resins. The p-toluenesulfonic acid catalyzed acetylation in ethyl acetate was found to be a generally applicable procedure for quick and easy determinations. Acetylation in pyridine requires longer reaction times. The end point of the subsequent titration of acetic acid is hard to recognize, thus giving uncertain results. The reaction time of acetic anhydride for each resin has to be carefully determined when perchloric acid is used as acetylation catalvst.