Protein interference

KDHRF A homologous restriction factor binds to C8 65KDHRF A homologous restriction factor, also known as C8 binding protein interferes with cell membrane pore-formation by C5b-C8 complex Kcat Catalytic constant a measure of the catalytic potential of an enzyme Ka Equilibrium dissociation constant kD Kilodalton Kd Dissociation constant KD Kallidin... 

All dose levels increased elimination of sodium, potassium, chloride, and urine protein interference with creatinine clearance at 200 mg/kg BW and higher (Santa Maria et al. 1986)... 

C.R. Yonzon, C.L. Haynes, X. Zhang, J.T. Walsh Jr. and R.P. Van Duyne, A glucose biosensor based on surface-enhanced Raman scattering improved partition layer, temporal stability, reversibility, and resistance to serum protein interference, Anal. Chem., 76(1) (2004) 78-85. 

Diabetes can involve misfolding of proteins that form in the endoplasmic reticulum (ER). The ER secretes certain hormones, enzymes, and antibodies, and so is a key player in our health. In some cases, the misfolded proteins interfere with carbohydrate metabolism leading to diabetes. 

Dominant negative effect, when the mutant protein interferes with function of the normal protein Osteogenesis imperfecta and the collagen 1A gene (COLIAI) Marfan syndrome and the fibrillin-1 gene (FBNI)... 

The best known inhibitors of glycosylation of proteins interfere with the lipid-dependent steps.35,228 Substances that specifically block reactions taking place after the transfer of the oligosaccharide to the protein are little known. As several, incompletely (or differently) glycosylated, viral glycoproteins arc still biologically active (see Section IV), these substances would escape the screening procedure based on... 

In the tryptophan reaction, aldehydes and fructose derivatives are among the most important interfering substances. Proteins interfere with the test, but Cohen66 eliminated complications due to such interference, and hence increased the value of the test, by developing a method for extracting the colored reaction-product of desoxyribose and tryptophan without simultaneous extraction of other reaction-products. 

EN62 Payne, R.B., Buckley, B.M. and Rawson, K.M. (1991). Protein interference with ion-selective electrode measurement depends on reference electrode composition and design. Ann. Clin. Biochem. 28, 68-72. 

The main limitations of the translocation system described here are that (a) many passenger proteins interfere with the structure of the toxin so that it cannot recognize the toxin receptor, and that (b) the passenger protein may not be able to unfold. We have tested a large number of proteins, and most of them are not translocated due to one of these problems (Klingenberg and Olsnes, 1996). This may also be a problem with smaller peptides, but usually less than with protein passengers. Conceivably, modification of the fusion proteins with polypeptide linkers and by mutations in the passenger protein may overcome the problem, but this will require a considerable amount of work in each case. 

Payne RB, Jones DP. Protein interferes with ionized calcium measurement at the reference electrode liquid junction, Ann Chn Biochem 1987 24 400-7. 

Different T3 immunoassays may show unexplained discrepancies between values for the same sera. Results from inter-laboratory quality assurance schemes also demonstrate a higher analytical variance for T3 than for T4 methods. Many factors have been suggested as accounting for these disparities, such as the lower quantity of T3 in sera, differences in antisera cross-reactivity, protein interferences, and different assay limits of detection. ... 

Ascorbic acid, increased intestinal pH, sulfide ion, phy-tate (inositol hexaphosphate in plants), and some dietary proteins interfere with its intestinal absorption. 

Kiachopoulos S, Bracher A, Winklhofer KF, Tatzelt J (2005) Pathogenic mutations located in the hydrophobic core of the prion protein interfere with folding and attachment of the glycosylphosphatidylinositol anchor. J Biol Chem 280 9320... 

Hydralazine. Vasodilator drug which causes systemic lupus erythematosus in a significant proportion of patients. Several predisposing factors have been identified dose (>25 mg) duration of therapy (mean 18 months) acetylator phenotype (slow) HLA type (DR4) gender (females males, 4 1). Antinuclear antibodies and antihydralazine antibodies detected in serum. Causes a Type III immune reaction. Mechanism is unclear but may involve reaction of parent drug or metabolite with protein. Interference with the complement system and interaction with nucleic acids also occur. Metabolism also may be mediated by myeloperoxidase in activated neutrophils. 

N. Zagris, M. Panagopoulou, N-glycosylated proteins interfere with the 1st cellular migration in early chick embryo, Int.J. Dev. Biol. 1992, 36, 439-443. 

Yosselson-Superstine, S., and Sinai, Y. 1986. Urine protein interference. Journal of Clinical Chemistry and Clinical Biochemistry 24 103-106. 

To determine the ESR, the patients blood is placed vertically in a small-bore glass tube. The speed with which the red blood cells sediment toward the bottom of the tube depends on what percentage of the red blood cells clump together and, thereby, become more dense. The degree of clumping is directly correlated with the presence of one or more of the first-phase proteins listed previously. These proteins interfere with what is known as the zeta-potential of the red blood cells, which normally prevents the red blood cells from clumping. Because many different proteins can individually alter the zeta-potential, the ESR is a nonspecific test for the presence of acute inflammation. 

VeUonen, K.-S., P. Honkakoski, and A. Urtti, Substrates and inhibitors of efflux proteins interfere with the MTT assay in cells and may lead to underestimation of drug toxicity. European Journal of Pharmaceutical Sciences, 2004. 23(2) 181-188. 

Polymer-coated nanoparticles in the 10-50 nm size range with a bismuth sulfide (61283) core and showing superior enhancement capabilities and a circulation time of greater than 2 h have been described. The polymer coating (polyvinylpyrrolidone) prevented aggregation and protein interference, and concentrated the contrast capabilities of the imaging agent. 

Attia AS, Ram S, Rice PA et al. Binding of vitronectin by the Motaxella catarrhalis UspA2 protein interferes with late stages of the complement cascade. Infect Immun 2006 74 1597-1611. 

Traditional wet-chemical procedures required serum or plasma proteins to be removed prior to further analysis this was achieved by precipitation, usually with acids such as trichloracetic acid or metal ions, e.g., zinc sulfate. If organic acid extraction were to be used, this would also precipitate proteins. Such methods are scarcely used in routine practice. Automated procedures can readily be adapted to determine colorimetric endpoint or rates of reaction the avoidance of protein interference is more difficult (see the section Large-capacity analyzers ). 

Preparation of samples for use in RRAs varies. If the substance of interest is in biological fluids (e.g., urine, spinal fluid, plasma) it may be possible to add fluid directly to the RRA. In many instances, however, components (salts, proteins) interfere with assay integrity. In this case, it is necessary to devise a preparation scheme suitable for use with the RRA and which does not alter the quantities of the substance of interest, or to incorporate an appropriate internal standard in the method (e.g., radioactive tracer amounts of the compound of interest preferably labeled with an isotope different from that incorporated in the ligand). In the case of natural product analysis, standard aqueous or organic extraction procedures are followed and the sample is freeze-dried or dried to provide the final preparation. Aqueous fractions can be redissolved in assay buffers whereas dimethylsulfoxide (DMSO) is a useful solvent for organic extracts since many RRAs tolerate < 1 % DMSO in the final assay. 

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