Guanidino Group Of Arginine Research Articles

Interaction of tropocollagen with protein-polysaccharide complexes: An analysis of the ionic groups responsible for interaction

Human intervertebral disc protein-polysaccharide complex (PP-L) has been separated by isoelectric focussing analysis into three main subunits and four minor components. PP-L interacted with tropocollagen in the isoelectric-focussing column to yield a single complex zone, containing both uronic acid and hydroxyproline, with an isoionic point intermediate between those of tropocollagen and PP-L. This complex, formed at 4°, was shown by electron microscopy to be in the form of fibrous long-spacing fibrils, whilst the complex formed at 37° consisted of native-type fibrils. Chemical and enzymic modification of the PP-L demonstrated that the sulphate group was largely responsible for interaction with tropocollagen during isoelectric focussing. The initial interaction was independent of the core protein and independent of the length of the glycosaminoglycan chains. The guanidino groups of arginine and the ϵ-amino groups of lysine were found to be the sites of interaction of tropocollagen with PP-L.

A new fluorescent method with phenanthrenequinone for the histochemical demonstration of arginine residues in tissues.

Phenanthrenequinone, in an alkaline ethanolic solution, is shown to be specific for the guanidino group of arginine in tissues. The fluorescence measured in chick erythrocyte nuclei is highly reproducible among areas on one slide and among different slides. Benzil and cyclohexanedione, two agents known to be specific for the guanidino group, prevent 85% of the fluorescence developed in the phenanthrenequinone reaction. Glyoxal blocks phenanthrenequinone reactivity only partially, while alkaline formaldehyde has little effect. The effects of fixation and postfixation of chick erythrocyte nuclei indicate that fluorescence is most intense after formalin fixation, and that conformational factors may prevent ethanolacetic acid-fixed nuclei from reacting completely. By means of protein precipitation and prolonged incubation in ethanol, it was shown that the fluorescent chromophore is strongly bound to phenanthrenequinone-reacted gelatin and to tissue sections. Excitation and emission spectra are presented for phenanthrenequinone-reacted arginine, gelatin and a tissue section.

Early changes in the binding between DNA and histone in human leucocytes exposed to phytohemagglutinin

Previously reported changes in the deoxyribonucleoprotein (DNP) complex of human leucocytes responding to phytohemagglutinin (PHA) were further investigated in the present work by using the alkaline bromphenol blue (BPB) binding reaction for basic proteins. The extraction of DNA preceding the BPB-binding was performed both in trichloroacetic acid (TCA) and in picric acid (PA). TCA liberates both arginine and lysine residues for the subsequent BPB-binding. PA, which was found to bind strongly to the guanidino-groups of arginine, mainly liberates the lysine residues for the following BPB-binding. By measuring the amounts of PA and BPB bound after PA-hydrolysis and BPB staining, information was obtained about the relative amounts of arginine and lysine in histone bound to DNA. In PHA-treated cells a 25% decrease in BPB-binding was observed after TCA-hydrolysis. No such decrease in BPB-binding could be demonstrated after PA-hydrolysis. However, as much as an 80% decrease was found in the PA-binding capacity. These results were interpreted as a reduced number of arginine residues in histone bound to the DNA-phosphate groups in cells exposed to PHA.

Mechanism of Reaction of Proteins with Reactive Dyes:II—Reactivity of Simple Model Compounds with Chlorotriazine Dyes

The chemistry of the functional groups in wool is described and the selection of appropriate model compounds for them is discussed. The measurement of the reactivities of these model compounds and possible mechanisms of their reactions are discussed. The nucleophilic anion is the important species in the reaction of a chlorotriazine dye with the thiol group in cysteine or the hydroxyl and phenolic groups in serine, threonine and tyrosineresidues. The reaction of a chlorotriazine dye with the amino groups of lysine and the N‐terminal amino acids, with the imidazole group of histidine and with the guanidinogroup of arginine takes place mainly with the unprotonated base. Evidence in support of these mechanisms is provided by an investigation of the reactions of the dye with aqueous ammonia and anhydrous liquid ammonia.

Modification of the Sakaguchi reaction: Spectrophotometric determination of arginine in proteins without previous hydrolysis

2,4-Dichloro-1-naphthol in alkaline solution becomes red on standing. It becomes red also upon addition of small concentrations of NaOCl and fades when higher concentrations of NaOCl are added. This instability of an alkaline solution of naphthol (probably due to its oxidation) has been interpreted as one of the reasons for the nonlinearity present in the Spectrophotometric determination of arginine with previous modifications of the Sakaguchi reaction. Another reason for this nonlinearity has been found in the fact that all amino acids react with alkaline solutions of 2,4-dichloro-1-naphthol, thus interfering with the spectrum specifically due to the guanidino group of arginine. These interferences are eliminated with the reagent suggested here which is obtained by dissolving 100 mg of 2,4-dichloro-1-naphthol in 100 ml of 5.0 n KOH and 180 ml of absolute alcohol, and then bringing it to a full color development by adding a small concentration of NaOCl. It was also found that the addition to the reaction mixture of 2 moles of KI for each mole of naphthol stabilizes the reaction products. Thus the reaction of naphthol with arginine is made stable; the plot of optical density (O.D.) versus concentration of arginine is linear and the slope passes through the origin. This method for the determination of arginine has been tested with solutions of various proteins without previous hydrolysis. The arginine content of these proteins has been found to be close to the values reported in the literature.

The union of protein and nucleic acid in the living cell and its demonstration by osmium staining

ABSTRACT The greater part of the osmium tetroxide that is reduced and bound by living cells in neutral solution is taken up by unsaturated lipids. The protein in mitochondria, muscle-fibres, connective tissue, red blood cells, See., takes up a smaller amount of osmium; but the basic proteins that are combined with DNA and RNA in the chromosomes, nucleoli, and cytoplasm do not react: their reactive groups are presumably held in salt linkages with the phosphate residues of the nucleic acids. If the cells are exposed to an acid medium (0.001 M acetic acid or saturated carbonic acid) these salt linkages are weakened, and chromosomes and cytoplasmic nucleoprotein will now take up large amounts of osmium and stain intensely with ethyl gallate. This effect of hydrogen ion concentration is reversible within the living cell. By the application of a series of blocking reagents it is concluded that the chief reactive groups on the proteins are the guanidino group of arginine, the e-amino group of lysine, the iminazole group of histidine, and the pyrrolidine group of proline. Tryptophane and cystein, though highly reactive, are perhaps less important quantitatively.

A new synthesis of the pentapeptide l-histidyl-l-phenylalanyl-l-arginyl-l-tryptophyl-glycine and its melanocyte-stimulating activity.

A SYNTHESIS of the pentapeptide H.His-Phe-Arg-Try-Gly.OH along classical lines has recently been described by Hofmann et al. 1. The amino-acid sequence of this peptide, which occurs in adrenocorticotropic (ACTH) and melanocyte-stimulating (MSH) hormones2, presents a number of considerable difficulties for chemical synthesis, chiefly owing to the presence of tryptophan, arginine and histidine. In this communication, we wish to report the synthesis of this pentapeptide in a stepwise manner beginning at the C-terminus with the p-(p′-methoxy-phenylazo)-benzyloxy carbonyl group (MZ group), described by one of us3, used as the amino-protecting agent. In addition, the p-toluenesulphonyl (tosyl) group was introduced to protect the guanidino group of arginine, since this protecting group resists catalytic hydrogenation and is easily removed by sodium in liquid ammonia. When the peptide was assayed either in the hypophysectomized frog or on frog skin in vitro, it was found to possess melanocyte-stimulating activity.