Determination of Minimal Concentrations of Biocorrosion Inhibitors by a Bioluminescence Method

By using a bioluminescence ATP assay, we have determined the minimal concentrations of some biocorrosion inhibitors (Kathon, Khazar, VFIKS-82, Nitro-1, Caspii-2, and Caspii-4) suppressing most common microbial corrosion inducers: Desulfovibrio desulfuricans, Desulfovibrio vulgaris, Pseudomonas putida, Pseudomonas fluorescens, and Acidithiobacillus ferrooxidans. The cell titers determined by the bioluminescence method, including not only fissiparous cells but also their dormant living counterparts, are two-to sixfold greater than the values determined microbiologically. It is shown that the bioluminescence method can be applied to determination of cell titers in samples of oil-field waters in the presence of iron ions (up to 260 mM) and iron sulfide (to 186 mg/l) and in the absence or presence of biocidal corrosion inhibitors.__________Translated from Prikladnaya Biokhimiya i Mikrobiologiya, Vol. 41, No. 4, 2005, pp. 429–434.Original Russian Text Copyright © 2005 by Efremenko, Azizov, Makhlis, Abbasov, Varfolomeev.     

c-IAP1 and c-IAP2 are critical mediators of tumor necrosis factor alpha (TNFalpha)-induced NF-kappaB activation

The inhibitor of apoptosis (IAP) proteins are a family of anti-apoptotic regulators found in viruses and metazoans. c-IAP1 and c-IAP2 are recruited to tumor necrosis factor receptor 1 (TNFR1)-associated complexes where they can regulate receptor-mediated signaling. Both c-IAP1 and c-IAP2 have been implicated in TNFalpha-stimulated NF-kappaB activation. However, individual c-IAP1 and c-IAP2 gene knock-outs in mice did not reveal changes in TNF signaling pathways, and the phenotype of a combined deficiency of c-IAPs has yet to be reported. Here we investigate the role of c-IAP1 and c-IAP2 in TNFalpha-stimulated activation of NF-kappaB. We demonstrate that TNFalpha-induced NF-kappaB activation is severely diminished in the absence of both c-IAP proteins. In addition, combined absence of c-IAP1 and c-IAP2 rendered cells sensitive to TNFalpha-induced cell death. Using cells with genetic ablation of c-IAP1 or cells where the c-IAP proteins were eliminated using IAP antagonists, we show that TNFalpha-induced RIP1 ubiquitination is abrogated in the absence of c-IAPs. Furthermore, we reconstitute the ubiquitination process with purified components in vitro and demonstrate that c-IAP1, in collaboration with the ubiquitin conjugating enzyme (E2) enzyme UbcH5a, mediates polymerization of Lys-63-linked chains on RIP1. Therefore, c-IAP1 and c-IAP2 are required for TNFalpha-stimulated RIP1 ubiquitination and NF-kappaB activation.     

Properties of the Urokinase-Type Plasminogen Activator Modified with Phenylglyoxal

A chemical modification of single-chain urokinase-type plasminogen activator (scu-PA) with phenylglyoxal under mild conditions resulted in scu-PA derivatives with various numbers of the modified Arg residues. The study of properties of the resulting derivatives demonstrated that the modification of 4–12 Arg residues did not cause any loss of the activator, fibrinolytic, and potential amidase activities of the activator. The scu-PA with four modified Arg residues was found to be the most stable derivative in human blood plasma; it causes a more efficient lysis of plasma clots than the native activator. Three of four modified Arg residues are supposed to be within the R178RHRGGS184 cluster, which was located in the superficial loop of the scu-PA globule and was shown to interact with a complementary series of negatively charged residues in the molecule of the main plasma inhibitor PAI-1. The neutralization of positively charged Arg residues in this cluster decreases the affinity of scu-PA and the two-chain urokinase-type plasminogen activator for PAI-1, which results in an enhancement of the stability in plasma and the fibrinolytic efficiency of the activator.     

Short chain oligogalacturonides induce ethylene production and expression of the gene encoding aminocyclopropane 1-carboxylic acid oxidase in tomato plants

Oligogalacturonic acids (OGAs), derived from plant cell wall pectin, have been implicated in a number of signal transduction pathways involved in growth, development and defense responses of higher plants. This study investigates the size range of OGAs capable of inducing ethylene synthesis in tomato plants, and demonstrates that in contrast with many other effects, only short chain OGAs are active. Oligomers across a range of DP from 2-15 were separated and purified to homogeneity by QAE-Sephadex anion exchange chromatography using a novel elution system. The OGAs were applied to tomato plants and assayed for their ability to induce ethylene gas release and changes in steady state levels of mRNA encoding the ethylene forming enzyme aminocyclopropane-1-carboxylic acid oxidase (ACO). The study demonstrated that only OGAs in the size range of DP4-6 were active both in eliciting ACO expression and in the production of ethylene.      

The nature of functional groups regulating the catalytic activity of prostaglandin endoperoxide synthetase

The influence of some reagents modifying NH2-, SH-groups or imidazole moiety, on the prostaglandin endoperoxide synthetase activity was studied. Acetaldehyde, pyridoxal phosphate, dithiobis (nitrobenzoic) acid and iodoacetamide were found not to affect the enzyme activity. The activity was abolished as a result of the interaction with p-chloromercuribenzoic acid and diethyl pyrocarbonate. The hemin completely protected the apo-enzyme against the inactivation with diethyl pyrocarbonate. The assumption about the presence of imidazole moiety in the active site of the enzyme was made.     

Kinetic characteristics of neuroleptic binding sites on human lymphocytes

The kinetics and equilibrium of the interaction of [3H]spiperone with binding sites on human lymphocytes have been studied using radioligand analyses. The process of [3H]spiperone binding to these sites can be explained by the model of ligand interaction with two independent binding sites (high-affinity site, KD1 = 3 nM, and low-affinity site, KD2 = 20 nM), thus confirming the heterogeneity of the sites on human lymphocytes.     

The macrokinetic behavior of an enzymatic system with an enzyme inactivated in the reaction

This study deals with the behavior of a heterogeneous multisubstrate enzymatic system under enzyme inactivation in a reaction. Electronic computer modeling data have been obtained for its macrokinetics at different modes: (1) under mixed inflow of the substrates and (2) under their spatial separation. The enzymatic membrane exhibits low sensitivity to a change in the external conditions as the substrates are intermixed on the boundary. Quite the contrary, in the case of spatial separation of the substrates, the product flow from the membrane has displayed abrupt fluctuations at different boundary conditions. This work also looks into the arrangement of the reaction zones in the membrane and their transitions under different conditions.