Activity Of Arg Research Articles

Two distinct phosphorylation pathways have additive effects on Abl family kinase activation.

The activities of the related Abl and Arg nonreceptor tyrosine kinases are kept under tight control in cells, but exposure to several different stimuli results in a two- to fivefold stimulation of kinase activity. Following the breakdown of inhibitory intramolecular interactions, Abl activation requires phosphorylation on several tyrosine residues, including a tyrosine in its activation loop. These activating phosphorylations have been proposed to occur either through autophosphorylation by Abl in trans or through phosphorylation of Abl by the Src nonreceptor tyrosine kinase. We show here that these two pathways mediate phosphorylation at distinct sites in Abl and Arg and have additive effects on Abl and Arg kinase activation. Abl and Arg autophosphorylate at several sites outside the activation loop, leading to 5.2- and 6.2-fold increases in kinase activity, respectively. We also find that the Src family kinase Hck phosphorylates the Abl and Arg activation loops, leading to an additional twofold stimulation of kinase activity. The autoactivation pathway may allow Abl family kinases to integrate or amplify cues relayed by Src family kinases from cell surface receptors.

Seminal arginase activity in infertility

Arginase (Arg) activity in seminal plasma and sperm cells from infertile men and healthy fertile donors was measured. There were no statistically meaningful differences in seminal plasma Arg activity between the two groups whereas sperm cells from oligospermic infertile men had a higher Arg activity compared with the controls. Some important correlations were established between sperm count and Arg activity (negative values) and sperm motility and Arg activity (positive values) in both sperm cells and plasma samples from infertile men. Results suggest that the arginine-nitric oxide pathway within sperm cells from oligospermic infertile men is disturbed by enhanced Arg activity. We think that this may play a part in sperm dysfunction and male infertility.

Influence of systemic arginine-lysine on immune organ function: An electrophysiological study

To test our hypothesis that arginine (Arg) and lysine (Lys) enhance immune activities via neuronal control of the thymus and the spleen, a jugular vein was cannulated for amino acid administration in male Wistar rats (∼ 300 g). In one group ( n = 5), an efferent nerve filament of the vagal thymus was isolated. In another group ( n = 5), splenic nerve efferents were isolated. Efferent firing rates were recorded before and for 60–90 minutes after 10 mM Arg-Lys in 0.5 ml saline intravenously (IV). Differences in firing rates were evaluated using analysis of variance (ANOVA) and t-test. IV Arg-Lys increased vagal efferent firing rate to the thymus; enhancing thymic lymphocyte release. IV Arg-Lys decreased firing rate in splenic efferents; enhancing natural killer (NK) cell activity. Therefore, Arg-Lys are detected by hepatoportal sensors, stimulating hepatic vagal afferents to the hypothalamus, with the efferent neuronal impulses from the hypothalamus modulating immune function in thymus and spleen, thereby demonstrating the mechanism of Arg and Lys immune enhancing activity.

Mutations at Pro67in the RecA Protein P-loop Motif Differentially Modify Coprotease Function and Separate Coprotease from Recombination Activities

The functional significance of residues in the RecA protein P-loop motif was assessed by analyzing 100 unique mutants with single amino acid substitutions in this region. Comparison of the effects on the LexA coprotease and recombination activities shows that Pro67 is unique among these residues because only at this position did we find substitutions that caused differential effects on these functions. One mutant, Pro67-->Trp, displays high constitutive coprotease activity and a moderate inhibitory effect on recombination functions. Glu and Asp substitutions result in low level constitutive coprotease activity but dramatically reduce recombination activity. The purified Pro67-->Trp protein shows a completely relaxed specificity for NTP cofactors in LexA cleavage assays and can use shorter length oligonucleotides as cofactors for cleavage of lambda cI repressor than can wild type RecA. Interestingly, both the mutant protein and wild type RecA can use very short oligonucleotides, e.g. (dA)6 and (dT)6, as cofactors for LexA cleavage. We have also found two mutations at position 67, which are completely defective for LexA coprotease activity in vivo but still maintain recombinational DNA repair (Pro67-->Lys) and homologous recombination (Pro67-->Lys and Pro67-->Arg) activities. These findings show that the recombination activities of RecA are mutationally separable from the coprotease function and that Pro67 is located in a functionally important position in the RecA structure.

Estimation of Arginine Metabolism in Putrefactive Bacteria Using Liquid Chromatography.

Liquid chromatography (LC) using on-column derivatization coupled with a columnswitching technique was developed to study the metabolism of amino acids in bacteria. Simultaneous analysis of 12 kinds of polyamines and their precursor amino acids was performed using this system. Degradation products of amino acids due to Photobacterium phosphoreum, a putrefactive bacterium, was analyzed by the LC method. The arginine (Arg) metabolism in the bacterium was found to be such that Arg was converted to agmatine by the Arg-decarboxylase system, and agmatine was subsequently converted to putrescine by agmatinase. The method was applicable to the determination of Arg, ornithine and lysine decarboxylase activities, Arg-dihydrolase activity and other enzyme activities in putrefactive bacteria.

EFFECT OF PSORALEN + ULTRAVIOLET‐A ON THE CHEMOTACTIC ACTIVITY OF POLYMORPHONUCLEAR NEUTROPHILS TOWARDS ANAPHYLATOXIN C5a DES ARG

Abstract— It was shown that psoralen + UV‐A inhibits the chemotactic activity of polymorphonuclear neutrophils towards anaphylatoxin C5a des Arg. This reaction required oxygen and there is a high possibility that the active oxygen species was in a singlet state. Oxygen did not act directly on C5a des Arg, but rather produced oxidized psoralen which inhibited C5a des Arg activity. The effect was dependent on the concentration and types of psoralen and on the UV‐A dose. Among the psoralens, the inhibitory effect of 4,5′,8‐trimethylpsoralen was the strongest, followed by 8‐methoxypsoralen and 3‐carbethoxypsoralen and finally 4,4′,6‐trimethylangelicin. Psoralen + UV‐A failed to inhibit the chemotactic activity towards chemotactants other than anaphylatoxin C5a such as casein, the cultured filtrate of E. coli, platelet‐activating factor, leukotriene B4, 5‐hydroxy‐6,8,11,14‐eicosatetraenoic acid and 12‐L‐hydroxy‐5,8,10,14‐eicosatetraenoic acid.

Biologically active products of complement and acute lung injury in patients with the sepsis syndrome.

To determine if biologically active products of complement appear during sepsis and to establish the relationship of these components to the respiratory and hemodynamic complications of sepsis, we measured C5a des Arg and C3a des Arg (radioimmunoassay), neutrophil chemotaxis, and neutrophil-aggregating activity in plasma obtained from 40 patients at the time sepsis was suspected clinically. Levels of C3a des Arg and C5a des Arg were elevated in 35 and 38 patients, respectively, and in all 25 with positive blood cultures. Highest C5a des Arg levels occurred in patients with hypotension (less than 90 mmHg) and/or acidemia. The C5a des Arg concentrations were significantly higher in patients with than in those without neutrophil-chemotactic activity. Neutrophil-aggregating activity was less sensitive an index of complement activation, as it was positive in only 8 patients and correlated poorly with C5a des Arg and C3a des Arg values. Using a composite scoring system to quantify sepsis-related pulmonary abnormalities, we found that neither biologic nor immunologic assays of complement activation products correlated with the initial severity nor predicted the development or worsening of associated acute lung injury.

EFFECT OF PSORALEN + ULTRAVIOLET-A ON THE CHEMOTACTIC ACTIVITY OF POLYMORPHONUCLEAR NEUTROPHILS TOWARDS ANAPHYLATOXIN C5a DES ARG

It was shown that psoralen + UV-A inhibits the chemotactic activity of polymorphonuclear neutrophils towards anaphylatoxin C5a des Arg. This reaction required oxygen and there is a high possibility that the active oxygen species was in a singlet state. Oxygen did not act directly on C5a des Arg, but rather produced oxidized psoralen which inhibited C5a des Arg activity. The effect was dependent on the concentration and types of psoralen and on the UV-A dose. Among the psoralens, the inhibitory effect of 4,5',8-trimethylpsoralen was the strongest, followed by 8-methoxypsoralen and 3-carbethoxypsoralen and finally 4,4',6-trimethylangelicin. Psoralen + UV-A failed to inhibit the chemotactic activity towards chemotactants other than anaphylatoxin C5a such as casein, the cultured filtrate of E. coli, platelet-activating factor, leukotriene B4, 5-hydroxy-6,8,11,14-eicosatetraenoic acid and 12-L-hydroxy-5,8,10,14-eicosatetraenoic acid.

Biological effects of the human complement fragments C5a and C5ades Arg on neutrophil function

The biological activity of human C5a was compared to its anaphylatoxin inactive form, C5ades Arg, using highly purified components. C5a was isolated from yeast-activated human serum and was converted to C5ades Arg by treatment with porcine carboxypeptidase B immobilized on Sepharose 6B. Both purified C5 fragments were homogeneous by polyacrylamide gel electrophoresis of radiolabeled peptides and by immunologic techniques. C5a caused increased vascular permeability in guinea pig skin with as little as 2 ng of injected material, whereas no detectable effect was seen with as much as 5000 ng of C5ades Arg. Both C5a and C5ades Arg stimulated cytochalasin B-treated human neutrophils to release the granule constituents myeloperoxidase, lysozyme, and β-glucuronidase, but not the cytoplasmic enzyme lactic dehydrogenase. However, 85- to 175-fold more C5ades Arg was required to give the same amount of release. A similar dichotomy of biologic effectiveness was seen for generation of the oxygen metabolite, superoxide anion, O2−, with or without cytochalasin B pretreatment of the cells. In contradistinction to earlier reports, C5ades Arg was chemotactic for human neutrophils in the absence of added serum between 100 to 10, 000 ng/ml, whereas C5a was active from 3 to 500 ng/ml. A 24-fold lower concentration of C5a was required to obtain a peak chemotactic response as measured by a leading front technique (5 ng/ml) as compared to a two-filter assay (120 ng/ml). In the absence of a gradient of the peptides, C5a and C5ades Arg induced enhanced random migration, i.e., exhibited chemokinetic activity. Both C5a and C5ades Arg desensitized neutrophils to further stimulation by C5a, as measured by granule secretion and chemotaxis. However, 25-to 50-fold more C5ades Arg than C5a was required for desensitization. The ability of C5ades Arg to cross-desensitize neutrophils suggests that C5ades Arg binds to the same neutrophil receptor as C5a but at a lower binding affinity. The studies reported here show that C5ades Arg is capable of interacting with neutrophils in a manner similar to that of C5a and that the difference between the two polypeptides is quantitative, not qualitative. Thus, the biologic activity of C5ades Arg and the presence of the serum carboxypeptidase B, which converts C5a to C5ades Arg, as well as the recently described helper factor for enhanced C5ades Arg chemotaxis combine to suggest that C5ades Arg may be an important phlogistic mediator in vivo.