Guanidyl Groups Research Articles

The molecular requirements for chemotactic attraction of leucocytes by proteins. Studies of proteins with synthetic side groups.

AbstractVarious small organic molecules were covalently linked to human serum albumin (HSA) and other proteins, and the products were tested for their ability to attract human peripheral blood neutrophil leucocytes in vitro. It was found that many substances, when attached to HSA, could increase its chemotactic activity. The chemotactic activity of the conjugates was not specifically inhibited by the presence of the conjugated substance in free solution. Thus it seems unlikely that chemotactic recognition of structurally altered proteins depends on a close stereospecific bonding between a cell surface receptor and the side group on the protein.In general, non‐polar side groups such as tosyl, propionyl and butyryl groups made the protein more chemotactic, than did polar side groups such as picryl, p‐sulphobenzylazo, guanidyl and carbamoylmethyl groups. We suggest that the chemotactic recognition of structurally altered proteins by neutrophils depends on hydrophobic bonding between non‐polar groups on the protein and those on the cell surface. Ionic groups would also be necessary for activity if the protein had many surface non‐polar groups: if there were no coulombic repulsions the non‐polar groups would become concealed by adhering to one another.

An X-ray study of the hydrogen bonding in the crystalline L-arginine phosphate monohydrate complex

The crystal structure of the L-arginine phosphate monohydrate complex has been determined from 1453 three-dimensional X-ray diffractometer data and refined by least-squares methods to a residual of R = 3.9 %. The X-ray results suggest that the L-arginine molecule is deprotonated at the carboxyl group and protonated at the guanidyl and amino groups and that the phosphate ion carries one negative charge. The L-arginine molecule is in a less extended conformation than found previously and both the guanidinium group and the carboxyl-C system are essentially planar. The crystal structure is interlaced by an intricate hydrogen-bonding scheme with apparently one bifurcated hydrogen bond involving atom N ~. The symmetrical guanidinium-phosphate ion geometry proposed for the interaction of basic proteins with DNA is not found in the L-arginine-phosphate monohydrate structure. It may therefore be inferred that the symmetrical complex is not necessarily preferred over a more complicated hydrogen bonding arrangement. The same structure has been published recently by Aoki, Nagamo & Iitaka (Acta Cryst. (1971). B27, 11).

Immunochemistry of erabutoxins.

Abstract Erabutoxins a and b, neurotoxic proteins of a sea snake Laticauda semifasciata , were treated with 2 per cent (w/v) formaldehyde. The modified erabutoxin b lost toxicity, changed in its ORD and CD properties and was modified on the amino, guanidyl and hydroxyphenyl groups of the amino acid residues. The modified erabutoxin b was monodisperse on ultracentrifuge and had a molecular weight of 68,800, about ten times of that of the original toxin. Antisera were obtained by injecting the formaldehyde-treated erabutoxin a or b into rabbits. Each 0·1 ml of the best preparations of the anti-erabutoxin a- and b-sera neutralized the toxicity of 25 μg of both erabutoxins. On double diffusion in agarose gel, the antisera formed a single continuous precipitation line with erabutoxins a and b and diiodoerabutoxin b. They did not precipitate, however, with laticotoxin a of Laticauda laticaudata or with cobrotoxin of Naja naja atra . The radioimmunoassay experiments showed that the affinity of the antibodies to laticotoxin a or cobrotoxin was less than one hundredth of that to erabutoxins.

A C-terminal arginine residue necessary for bacteriophage T4D tail assembly

Arginine and certain arginine analogs have been found to inhibit reversibly Escherichia coli T4D bacteriophage tail assembly in in vitro complementation experiments. Active compounds all possessed unaltered carboxyl groups and a terminal guanidyl group. Using bacterial extracts prepared after infection with T4D amber mutants defective in different stages of assembly, it was found that the addition of the initial portion of the tail sheath to the substructure consisting of tail core plus tail plate was prevented by these compounds. In the presence of an inhibitor, tail intermediates accumulated. After the initial attachment of sheath monomers, further tail assembly (and head assembly) was resistant to these compounds. The relative ability of these various arginine-like compounds to inhibit tail assembly correlated with their ability to disrupt the tail structure of intact T-even phage particles. Carboxypeptidase B treatment of these bacterial extracts also prevented in vitro T4D tail assembly apparently by a direct enzymic attack on a C-terminal arginine residue of a protein of the phage tail. This inhibition by Carboxypeptidase B treatment was irreversible and the site of attack of the enzyme was found to be a component of the tail plate. The pattern of sensitivity of the various stages of tail assembly to the treatment by Carboxypeptidase B paralleled the sensitivity to inhibition by arginine-like compounds. These results support the conclusions (1) that the T4D tail plate contains a protein(s) with a C-terminal arginine residue(s) which during assembly forms polar bonds involving both its carboxyl and guanidyl groups with another phage component of the tail substructure; (2) added arginine prevents in vitro tail assembly by competing with the C-terminal arginine residues for the receptors; and (3) Carboxypeptidase B treatment prevents tail assembly by removing the C-terminal arginine residues.

Octopine déshydrogénase Purification et propriétés catalytiques

Octopine dehydrogenase: Purification and catalytic properties 1. I. Octopine dehydrogenase, an NAD + enzyme, which catalyzes the dehydrogenation of octopine into arginine plus pyruvale, has been purified from muscles of Pecten maximus. It is homogeneous on analytical ultracentrifugation and disc electrophoresis. 2. 2. The enzyme contains no such metal cofactor as Fe 2+, Mn 2+, Zn 2+. 3. 3. The Michaelis constants are: 1.5·10 −3 M for octopine, arginine and pyruvate, 1.5·10 −4 M for NAD + and 4·10 −5 M for NADH. 4. 4. Substrate analogs with a guanidyl (guanidinobutane) or a carboxyl group (valeric acid) or both of them (δ-guanidinovaleric acid) are competitive inhibitors of the octopine forming reaction. In the dehydrogenation reaction, compounds with only one of these groups are competitive inhibitors whereas those possessing both guanidyl and carboxyl groups are not.

The interaction of aldehydes with collagen

The interaction of a series of aldehydes with collagen has been examined. Substitution of amino groups, as assessed by the formol titration, varies with the aldehyde and is greatest with formaldehyde, acrolein, succinaldehyde and glutaraldehyde and least with propionaldehyde and adipaldehyde. Except with formaldehyde, glyoxal and dialdehyde starch there is a corresponding decrease in lysine and hydroxylysine recoverable on hydrolysis, suggesting that the bond formed is relatively stable. Most of the amino groups reacting appear to be involved in cross-links. Losses of lysine are accompanied by increase in ultraviolet absorption of the hydrolysates with, in some cases, a maximum at 265 mμ. With glutaraldehyde three distinct ultraviolet absorbing fractions can be separated on Sephadex G-10. One of these appears to be a compound containing two lysine and six glutaraldehyde residues. Glyoxal and other compounds containing adjacent carbonyl groups reacted with guanidyl groups of arginine under acid conditions. One primary product is formed in the cold which on heating in 6 M HCl gives a second ninhydrin positive compound. The implication of the results with respect to the natural cross-links in collagen is briefly discussed.

Sur la réactivité des fonctions ionisables des trypsinogènes de bœuf et de proc

Summary The reactivity of ionisable side-chain groups, as measured by titrimetric techniques, has been determined for bovine and porcine trypsinogens. The number of α, β and γ-carboxyl, α- et e-amino, phenolic and guanidyl groups agrees well with data obtained by amino acid analysis. Normal pK values are found for the e-amino groups. However, the abnormal titration behavior of the imidazole, phenolic and carboxyl groups underlines their unique character in these proteins. 1. The imidazole groups (3 in bovine and 4 in porcine trypsinogen) are found to fall into three classes: Two imidazoles in porcine trypsinogen and one in bovine trypsinogen have normal pKs (6.5 and 6.8 respectively). One imidazole in each trypsinogen has an abnormally low pit (5.7). One imidazole in each trypsinogen had an abnormally high pit (8.3 or 7.8). 2. The value of the electrostatic factor ω, empirically calculated from the titration curve of the carboxyl groups, is abnormally high in both proteins when compared with the values obtained by theoretical calculation, titration of trypsinogen at alkaline pH or titration of bovine chymotrypsinogen A at any pH. Several of the carboxyl groups may have pit's lower than the normal value (4.4–4.5). 3. The spectrophotometric titration of the tyrosine residues revealed 4 of the 8 in porcine trypsinogen and 6 of the 10 in bovine trypsinogen to be masked. The unmasking of these groups occurs in several consecutive first-order reactions and is complete only at pH values above 13 or in 6 M urea. Ca2+ stabilize the conformation of the molecule, as revealed by an antagonistic effect on tyrosine unmasking; the trypsins formed by trypsinogen autoactivation are more stable than their precursors towards alkaline denaturation. The autoactivation of porcine trypsinogen does not change the number of masked tyrosines. The autoactivation of bovine trypsinogen involves the unmasking of one residue of tyrosine.

Hydrogen-ion equilibria of wheat gluten in guanidine-hydrochloride solutions

Hydrogen-ion titration curves of wheat gluten have been studied in 2 and 4 M guanidine-hydrochloride (G-HCl) at 25 °C. The data were analyzed by equations treating the electrostatic effect as an empirical factor. The ionizing groups per 10 5 gm gluten and their intrinsic p K's at 25 °C in 2 and 4 M G-HCl are: 29 carboxyl (4.54, 4.48), 15 imidazole (6.49, 6.56), 2 α-amino (8.5, 7.7), 1 sulfhydryl (10.0, 9.5), 20 tyrosyl (9.97, 9.97), and 9 lysyl (10.4, 10.4). The number and intrinsic p K of guanidyl groups cannot be determined in G-HCl solutions. The ionizing groups all appear normal. The empirical electrostatic factor w at acid pH was considerably larger than it was at alkaline pH, and a larger decrease in w was observed in alkaline than in acid solutions when the solvent was changed from 2 to 4 M G-HCl. These changes in w suggest that the conformation of gluten depends on pH and that the conformation in acid solution is more stable. Different methods for purifying G-HCl are discussed.

Hydrogen ion equilibria of wheat glutenin and gliadin

Hydrogen ion titration curves of twice-precipitated wheat glutenin and gliadin have been obtained in 3 M urea plus 0.15 M KCl at 25 °C. The data have been analyzed by equations treating the electrostatic effect as an empirical factor. The ionizing groups per 10 5 g. glutenin, and their intrinsic p K's at 25 °C. are: 38 carboxyl (4.76), 13 imidazole (6.6), 2 α-amino (8.4), 1 sulfhydryl (9.4), 23 tyrosyl (10.42), and 12 lysyl (10.6); those for gliadin are: 22 carboxyl (4.85), 14 imidazole (6.45), 2 α-amino (8.0), 1 sulfhydryl (10.0), 16 tyrosyl (10.31), and 5 lysyl (10.7). The guanidyl groups with p K greater than 13 do not affect the titration curves except through the net charge Z of glutenin and gliadin. The ionizing groups all appear to be normal. Empirical values of the electrostatic factor, w, are significantly larger for carboxyl groups than for tyrosyl groups. This change in w suggests that the conformations of both molecules depend on pH.

Hydrogen-ion equilibria of wheat gluten

Hydrogen-ion titration curves of wheat gluten have been studied in 3 M urea plus 0.15 M KCl at 25 °C. Ionizing groups per 10 5 g. gluten and their intrinsic p K's at 25 δC. are: 29 carboxyl (4.77), 15 imidazole (6.43), 2 α-amino (8.4), 1 sulfhydryl (10.1), 20 tyrosyl (10.26), and 9 lysyl (10.78). The guanidyl groups (p K > 13) affect the titration curve only through the net charge, Z, of gluten. The ionizing groups all appear to be normal although the intrinsic p K of the imidazole groups is on the low side. The empirical electrostatic factor w at acid pH was considerably larger than it was at alkaline pH, and this difference suggests a conformation change has occurred. The titration results agree with the amino acid and other analyses within experimental error.

Histochemical observations onActinomyces bovisgranules

The “clubs“, found at the perifery of the “sulfur granules” in Actinomyces infection, are composed chiefly of a highly polymerized basic protein rich in guanidyl, indole, and phenolic groups; sulfhydryl groups are absent. The clubs appear to be made of a material actively secreted by the filaments. It is hypothesized that some product or products of animal protein decomposition which are metabolized by the actinomycete trigger and maintain club formation in vivo, and that the club prevents phagocytosis or enzymatic digestion of the filaments on the one hand but proscribes further growth of the filaments on the other. New growth of the parasite takes place by extension of non-clubbed filaments at the perifery of the granule or by deposition of coccoid elements phagocytized by leucocytes.

The Reaction of Clupeine and Salmine with Nitrous Acid Reactivity of their N-Terminal and Guanidyl Groups

アルギニン,アルギニン含有ペプチドおよびクルペインについて長時間にわたる亜硝酸との反応を検圧式VanSlyke法によりしらべて,グアニジン基の反応性を検討した結果,いずれの試料についても反応時間が長くなるにしたがってグアニジン基も徐々に反応することを認めた。クルペインおよびサルミンの遊離アミノ基(N-末端基)を定量分析した。そして,上記の結果にもとづきその定量値へのグアニジン基の寄与について考察した。これを考慮にいれて,クルペインは調製品によって1分子(分子量6000)あたり0.5～0.9当量のN-末端アミノ基を有し,残りはイミノ基と考えられる。サルミンはN-末端基としてほとんどアミノ基をもたず,大部分がイミノ基であると推定され,既報のDNP法によるN-末端分析の結果と一致する。

Antigenicity of avidin.

AVIDIN has been shown to bind the vitamin biotin, but the mechanism of binding is still unknown. Modification of the avidin molecule by acetylation, esterifieation or by blocking the amide, guanidyl, imidazole and phenolic groups did not result in a loss of its ability to bind biotin1.

Isolation and characterization of a trypsin inhibitor from lima beans

1. 1. The purification of a lima bean protein fraction of high trypsin-inhibiting activity is described. The active protein was freed from inert crystallizable protein. 2. 2. The inhibitor shows remarkably high sulfur (5.5%) and cystine (16%) contents. Preliminary amino acid analyses are presented. 3. 3. The inhibitor is relatively resistant to denaturing conditions. It is not attacked by pepsin or papain. 4. 4. The average molecular weight of the concentrate was approximately 10,000 by osmotic pressure and ultracentrifugal analysis. 5. 5. The inhibitor is not inactivated by extensive esterification of its carboxyl groups, or by iodination and coupling of its phenolic and imidazole groups. Blocking of part of the amino and amide or guanidyl groups, sulfation of the hydroxyl groups, or extensive reduction of the disulfide bonds destroys its activity. 6. 6. Marked differences exist between the properties and essentiality of groups of the lima bean inhibitor and those of ovomucoid and the soybean inhibitor.

The essential groups of insulin

Insulin has been treated under carefully controlled conditions with acetic anhydride, ketene, aromatic isocyanates, iodine, diazobenzene sulfonic acid, phosphorous pentoxide, thioglycol, formaldehyde and other reagents, either singly or in sequence. From assays of the reaction products, and from data in the literature, the following conclusions have been derived: 1. 1. Neither acetylation, nor other reactions involving most of the amino groups, nor sulfation of most of the aliphatic hydroxyl groups causes inactivation of the hormone. 2. 2. Addition of methylol to part of the amide or guanidyl groups, or iodination of half of the phenolic groups, or coupling of part of the latter as well as a few imidazole groups (with diazobenzene sulfonic acid), causes little if any loss of activity. 3. 3. Reduction of most of the disulfide bonds, or esterification of most of the carboxyl groups, or extensive iodination or coupling of phenolic and imidazole groups causes marked inactivation. 4. 4. The partially coupled insulin, combined with protamine, appears to be less soluble and possibly more protracted in its action than standard protamine insulin.

The Reaction of Formaldehyde with Proteins. V. Cross-linking between Amino and Primary Amide or Guanidyl Groups

The Reaction of Formaldehyde with Proteins. V. Cross-linking between Amino and Primary Amide or Guanidyl Groups

Reaction of Formaldehyde with Proteins. II. Participation of the Guanidyl Groups and Evidence of Crosslinking

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReaction of Formaldehyde with Proteins. II. Participation of the Guanidyl Groups and Evidence of CrosslinkingHeinz Fraenkel-Conrat and Harold S. OlcottCite this: J. Am. Chem. Soc. 1946, 68, 1, 34–37Publication Date (Print):January 1, 1946Publication History Published online1 May 2002Published inissue 1 January 1946https://doi.org/10.1021/ja01205a011RIGHTS & PERMISSIONSArticle Views308Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (505 KB) Get e-Alerts Get e-Alerts