Reactions of cellulose isothiocyanates with thiol and amino compounds.

A cellulose isothiocyanate has been prepared by treatment of cellulose with 2,4-di-isocyanatotoluene followed by hydrolysis and reaction of the resulting amine with thiophosgene. The cellulose isothiocyanate was characterized by its binding capacity with respect to [14C]-glycine, [131 I]-human serum albumin, and 2-mercaptoethanol. An analytical method for binding capacity, based on reaction with [35 S]-alpha-toluenethiol, was developed. Because of the aromatic character of the NCS group of the cellulose isothiocyanate, the covalently bonded thiol can be quantitatively liberated.     

Quantitative aspects of the Ninhydrin-Schiff reaction on amino cellulose films and tissue sections

Summary In the ninhydrin-Schiff reaction primary amino groups are converted by oxidation with ninhydrin to aldehyde groups which are subsequently stained with pararosanilin. Amino cellulose films, used as a model, and sections of muscle tissue were submitted to this reaction. The amino groups were stained before and after the ninhydrin reaction with dinitrofluorobenzene and the generated aldehyde groups were stained with dinitrophenyl-hydrazine. The molar extinction coefficients used for the calculation of the molar amounts of chromophores from extinction values, and the conditions for maximal staining intensity were determined on the amino cellulose model. With these data the yields of the different steps in the reaction sequence could be calculated in molar amounts from the extinction measurements. The results showed that from the amino groups originally present in the tissue sections less than 40% were converted by ninhydrin. About 90% of the converted amino groups were found as aldehyde groups and from these only 7% reacted with pararosanilin. On amino cellulose similar data were obtained. Attempts were made by modification of the conditions in the ninhydrin oxidation step to increase the overall yield of the reaction. These were only partially successful, but indicate that further quantitative study of other reaction conditions and different aldehyde generating agents could be promising.     

The reaction of sulfhydryl groups with carbonyl compounds

The sulfhydryl groups of L-cysteine and reduced glutathione (GSH) react nonenzymatically with formaldehyde (F), acrolein (Al), acetaldehyde (AA), malondialdehyde (DAM), pyruvate (P), oxoglutarate (oxo-G) and glucose (G) to form thiazolidine derivatives. These reactions show different velocities and the adducts formed show different stabilities. The equilibrium constants K, as well as the rate constants kr for the reverse reaction, show considerable variation. The carbonyls reveal higher reactivity with sulfhydryl group of L-Cys than with those of GSH, and the stability of the adducts is higher than that of GSH. Al, F and AA react more rapidly with both thiol compounds than the other carbonyls, but the adducts are less stable. The sulfhydryl groups level of bovine serum albumin as well as those of high- and low-molecular thiols of human plasma is reduced in the presence of Al, F or DAM.     

The separation of nucleic acids and related compounds on nucleobase-coupled cellulose

The affinity chromatography on uracil-coupled cellulose was carried out for the separation of nucleosides, nucleotides and oligonucleotides. Adenine derivatives exhibited a high affinity to uracil-cellulose, and sequencial isomers of oligonucleotides containing adenine residue were resolved. Poly(A) was strongly bound to uracil-cellulose and recovered by the elution with 7M urea. This procedure was extended to the isolation of mRNA containing poly(A) sequences.