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At least 433 records · Page 24Linked to original sources
PubMed2000

Two distinct stages in the transition from naive CD4 T cells to effectors, early antigen-dependent and late cytokine-driven expansion and differentiation.

Efficient peptide presentation by professional APC to naive and effector CD4 T cells in vitro is limited to the first 1-2 days of culture, but is nonetheless optimum for effector expansion and cytokine production. In fact, prolonging Ag presentation leads to high levels of T cell death, decreased effector expansion, and decreased cytokine production by recovered effectors. Despite the absence of Ag presentation beyond day 2, T cell division continues at a constant rate throughout the 4-day culture. The Ag-independent later stage depends on the presence of IL-2, and we conclude optimum effector generation depends on an initial 2 days of TCR stimulation followed by an additional 2 days of Ag-independent, cytokine driven T cell expansion and differentiation.

Amino Acid Sequence↗
PubMed2003

A pool of central memory-like CD4 T cells contains effector memory precursors.

The L51S mutation in the D10.G4.1 TCR alpha-chain reduces the affinity of the TCR to its ligand by affecting the interactions among the TCR, the beta-chain of I-A(k), and the bound peptide. We show that this mutation drives the generation of a pool of memory CD44(high)CD62L(neg)CD45RB(neg) CD4 TCR transgenic T cells. Their activation threshold is low, such that they proliferate in response to lower concentrations of agonist peptides than naive L51S CD4 T cells. Unlike effector memory CD4 T cells, however, they lack immediate effector function in response to TCR stimulation. These cells express IL-2R alpha only after culture with specific peptide. Although they can be recovered from lymph nodes, the majority lack the expression of the lymph node homing receptor CCR7. When these cells receive a second TCR stimulation in vitro, they differentiate into potent Th2-like effector cells, producing high levels of IL-4 at doses of agonist peptide too low to stimulate cytokine release from similarly differentiated naive L51S CD4 T cells. Having these properties, the L51S TCR transgenic memory CD4 T cells cannot be classified as either strict central memory or effector memory, but, rather, as a pool of memory T cells containing effector memory precursors.

Amino Acid Substitution↗
PubMed2003

The FcR gamma subunit and Syk kinase replace the CD3 zeta-chain and ZAP-70 kinase in the TCR signaling complex of human effector CD4 T cells.

The TCR-mediated signals required to activate resting T cells have been well characterized; however, it is not known how TCR-coupled signals are transduced in differentiated effector T cells that coordinate ongoing immune responses. Here we demonstrate that human effector CD4 T cells up-regulate the expression of the CD3zeta-related FcRgamma signaling subunit that becomes part of an altered TCR/CD3 signaling complex containing CD3epsilon, but not CD3zeta. The TCR/CD3/FcRgamma complex in effector cells recruits and activates the Syk, but not the ZAP-70, tyrosine kinase. This physiologic switch in TCR signaling occurs exclusively in effector, and not naive or memory T cells, suggesting a potential target for manipulation of effector responses in autoimmune, malignant, and infectious diseases.

Adult↗
PubMed2004

A spontaneously arising pancreatic tumor does not promote the differentiation of naive CD8+ T lymphocytes into effector CTL.

In this report, we address whether a growing tumor provides sufficient inflammatory signals to promote activation, clonal expansion, and acquisition of effector functions by naive tumor-specific CD8(+) T lymphocytes. CD8(+) T lymphocytes obtained from hemagglutinin (HA)-specific clone 4 TCR-transgenic mice were injected into recipient mice that spontaneously develop pancreatic tumors expressing HA as a tumor-associated Ag (RIP-Tag2-HA mice). When 3 x 10(6) clone 4 CD8(+) T cells were transferred into tumor-bearing mice, the cells became activated in the pancreatic lymph nodes where they proliferated and acquired effector functions such as cytolytic activity and IFN-gamma production. Surprisingly, reducing the number of adoptively transferred CD8(+) T cells led to a parallel reduction in the proportion of the activated cells that exhibited effector functions, suggesting that CTL differentiation was induced by the large numbers of activated CD8(+) T cells and not the tumor environment. Provision of tumor-specific CD4(+) helper cells provided the signals required to promote both the development of CTL effector functions and increased clonal expansion, resulting in tumor eradication. Considering that only small numbers of tumor-specific CD8(+) T cells would be present in a conventional T cell repertoire, these data suggest that tumor growth alone may not provide the inflammatory signals necessary to support the development of CD8(+) T cell effector functions.

Adoptive Transfer↗
PubMed2005

Glucose availability regulates IFN-gamma production and p70S6 kinase activation in CD8+ effector T cells.

Differentiation of CD8+ T cells from the naive to the effector state is accompanied by changes in basal gene expression profiles that parallel the acquisition of effector functions. Among these are metabolism genes, and we now show that 2C TCR transgenic effector CD8+ T cells express higher levels of glycolytic enzymes and display greater glucose uptake, a higher glycolytic rate, and increased lactate production compared with naive cells. To determine whether glucose was required for effector T cell functions, we regulated glucose availability in vitro. Glucose deprivation strongly inhibited IFN-gamma gene expression, whereas IL-2 production was little affected. Inhibition correlated with diminished phosphorylation of p70S6 kinase and eIF4E binding protein 1 and a requirement for de novo protein synthesis, whereas other signaling pathways known to regulate IFN-gamma expression were unaffected. Together, our data reveal that optimal induction of IFN-gamma transcription is a glucose-dependent process, indicate that there are undefined factors that influence IFN-gamma expression, and have implications for regulation of the effector phase of CD8+ T cell responses in tissue microenvironments.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Dynamic differentiation of activated human peripheral blood CD8+ and CD4+ effector memory T cells.

Two functionally different memory T cell subsets were originally defined based on their different CCR7 expression profile, but the lineage relationship between these subsets referred to as central memory T cells (T(CM)) and effector memory T cells (T(EM)), is not resolved. A prevalent model proposes a linear progressive differentiation from T(CM) to T(EM). Our results demonstrate that on activation, human CCR7-CD62L- peripheral blood CD8+ and CD4+ T(EM) cells exhibit a dynamic differentiation, involving transient as well as stable changes to T(CM) phenotype and properties. Whereas the larger fraction of T(EM) cells increases expression of effector molecules, such as perforin or IFN-gamma, a smaller fraction first acquires CCR7 expression. We demonstrate that this acquisition of lymph node homing potential is associated with strong proliferation similar to that of activated T(CM) cells. After proliferation, most of these cells lose CCR7 expression again and acquire effector functions (e.g., perforin production). A small proportion (approximately 6%), however, maintain phenotypic and functional T(CM) properties over a long time interval. These results suggest that T(EM) cells provide immediate effector function by a fraction of cells as well as self-renewal by others through up-regulation of CCR7 followed by either secondary peripheral effector function or long term maintenance of T(CM)-like properties.

CD4 Antigens↗
PubMed2005

Critical role for CD103+CD8+ effectors in promoting tubular injury following allogeneic renal transplantation.

Immune destruction of the graft renal tubules is an important barrier to the long-term function of clinical renal allografts, but the underlying mechanisms remain obscure. CD103-an integrin conferring specificity for the epithelial cell-restricted ligand, E-cadherin-defines a subset of CD8 effectors that infiltrate the graft tubular epithelium during clinical rejection episodes, predicting a causal role for CD103+CD8+ effectors in tubular injury. In the present study, we used rodent transplant models to directly test this hypothesis. Surprisingly, CD8 cells infiltrating renal allografts undergoing unmodified acute rejection did not express significant levels of CD103. However, we demonstrate that a brief course of cyclosporine A to rat renal allograft recipients promotes progressive accumulation of CD103+CD8+ cells within the graft, concomitant with the development of tubular atrophy and interstitial fibrosis. As in the known clinical scenario, graft-associated CD103+CD8+ cells exhibited a T effector phenotype and were intimately associated with the renal tubular epithelium. Treatment with anti-CD103 mAb dramatically attenuated CD8 infiltration into the renal tubules and tubular injury. Mouse studies documented that CD103 expression is required for efficient destruction of the graft renal tubules by CD8 effectors directed to donor MHC I alloantigens. Taken together, these data document a causal role for CD103+CD8+ effectors in promoting tubular injury following allogeneic renal transplantation and identify novel targets for therapeutic intervention in this important clinical problem.

Animals↗
PubMed1999

Development of CD8+ effector T cells is differentially regulated by IL-18 and IL-12.

We investigated the effects of IL-18 on the development of CD8+ effector T cells in DBA/2 anti-BDF1 whole spleen cell MLC and compared the results with those of IL-12. Addition of IL-18 to the MLC resulted in a twofold increase in CD8/CD4 ratios compared with the control cultures when cells were expanded in IL-2-containing medium following MLC. Purified CD8+ T cells recovered from the IL-18-stimulated MLC produced 20- to 30-fold more IFN-gamma after secondary stimulation with C57BL/6 spleen cells or anti-CD3 mAb, and exhibited strong allospecific CTL activity. Neither IL-18 nor IL-18-supplemented culture supernatants from DBA/2 anti-BDF1 MLC induced type I CD8+ effector T cells when purified CD8+ T cells were used as responder cells in primary MLC. Furthermore, CD4+ T cell depletion from the responder cells abrogated the IL-18-induced increase in secondary IFN-gamma production by CD8+ T cells, suggesting that IL-18-induced type I effector CD8+ T cell development was CD4+ T cell dependent. In marked contrast, adding IL-12 to primary MLC decreased CD8/CD4 ratios by 50% and suppressed secondary IFN-gamma production and CTL activity by CD8+ T cells regardless of concentration, whereas Th1 development was promoted by IL-12. Moreover, both IL-12 and IL-18 efficiently induced type I CD8+ effector T cells in C57BL/6 anti-BDF1 MLC. These findings show that IL-18 plays an important role in the generation of type I CD8+ effector T cells, and further suggest that functional maturation of CD8+ T cells is differentially regulated by IL-18 and IL-12.

Animals↗
PubMed1999

Tumor regression after adoptive transfer of effector T cells is independent of perforin or Fas ligand (APO-1L/CD95L).

The adoptive transfer of tumor-specific effector T cells can result in complete regression and cure mice with systemic melanoma, but the mechanisms responsible for regression are not well characterized. Perforin- and Fas ligand (APO-1/CD95 ligand)-mediated cytotoxicity have been proposed as mechanisms for T cell-mediated tumor destruction. To determine the role of perforin and Fas ligand (FasL) in T cell-mediated tumor regression in a murine melanoma model, B16BL6-D5 (D5), we generated D5-specific effector T cells from tumor vaccine-draining lymph nodes of wild type (wt), perforin knock out (PKO), or FasL mutant (gld) mice and treated established D5 metastases in mice with the same genotype. Effector T cells from wt, PKO and gld mice induced complete regression of pulmonary metastases and significantly prolonged survival of the treated animals regardless of their genotype. Complete tumor regression induced by PKO effector T cells was also observed in a sarcoma model (MCA-310). Furthermore, adoptive transfer of PKO and wt effector T cells provided long-term immunity to D5. Therapeutic T cells from wt, PKO, or gld mice exhibit a tumor-specific type 1 cytokine profile; they secrete IFN-gamma, but not IL-4. In these models, T cell-mediated tumor regression and long-term antitumor immunity are perforin and FasL independent.

Adoptive Transfer↗
PubMed2000

Molecular decipherment of Rho effector pathways regulating tight-junction permeability.

We reported recently that the activation of RhoA induced an increase in transepithelial electrical resistance (TER). To clarify effectors of Rho for this RhoA-induced regulation of tight-junction permeability, we introduced two effector-loop mutants of constitutively active RhoA(V14), RhoA(V14/L40) and RhoA(V14/C42), into Mardin-Darby canine kidney cells in an isopropyl beta-D-thiogalactoside-inducible expression system. RhoA(V14) and the two effector-loop mutants interacted in vitro with the Rho-binding domain of Rho-associated kinase, ROKalpha. Next we examined two parameters of Rho functions, stress-fibre formation and TER elevation, induced by RhoA(V14). Stress-fibre formation was induced by RhoA(V14/C42) but not by RhoA(V14/L40). On the other hand, TER elevation was induced by neither RhoA(V14/L40) nor RhoA(V14/C42). RhoA-associated kinase inhibitor, Y-27632, inhibited both stress-fibre formation and TER elevation induced by RhoA(V14). These results demonstrated that RhoA-induced regulation of tight-junction permeability is mediated by Rho-associated kinase and at least one other unidentified effector, the coupling to RhoA being disrupted by mutation at position 40 or 42 in the effector loop.

Animals↗
PubMed1976

The effector cells in human peripheral blood mediating mitogen-induced cellular cytotoxicity and antibody-dependent cellular cytotoxicity.

The identity of the effector cells in human peripheral blood capable of mediating mitogen-induced cellular cytotoxicity (MICC) and antibody-dependent cellular cytotoxicity (ADCC) was investigated utilizing effector cell populations consisting of purified polymorphonuclear leukocytes, macrophages, lymphocytes, and cell surface immunoglobulin (sIg)-negative and sIg-positive lymphocyte subpopulations obtained by Sephadex anti-Fab immunoabsorbent column fractionation techniques. Chicken erythrocytes (CRBC) and Chang liver cells were used as target cells in both cytotoxicity assays. With CRBC targets MICC was mediated by polymorphonuclear leukocytes, macrophages, sIg-positive lymphocytes (B cells), and sIg-negative lymphocytes. On the contrary, with Chang liver cells as targets, MICC was mediated only by lymphocytes, and effector cells occurred exclusively in sIg-negative lymphocyte subpopulations containing thymus-derived lymphocytes (T cells). Further purification of sIg-negative lymphocyte subpopulations on antigen-antibody coated plastic surfaces yielded a nonadherent T lymphocyte population depleted of Fc receptor-bearing lymphocytes that was capable of mediating MICC against both CRBC and Chang cell targets. With use of CRBC targets, ADCC was mediated by polymorphonuclear leukocytes, macrophages, and sIg-negative lymphocyte subpopulations. However, with Chang cell targets, ADCC was mediated only by lymphocytes, and effector cells were present only in sIg-negative lymphocyte subpopulations. SIg-positive lymphocytes (B cells) and T lymphocytes were not effective in mediating ADCC against either CRBC or Chang cell targets. These studies demonstrate that the nature of the target cell employed in MICC and ADCC reactions is of critical imporatnce in defining the effector cell(s) capable of mediating cytotoxicity.

Animals↗
PubMedDate not supplied

Generation of cytotoxic effector lymphocytes by MLTC using tumor cells genetically modified to secrete interleukin-2.

The in vitro generation of effector lymphocytes cytotoxic to cancer cells, was investigated with a mixed lymphocyte-tumor culture (MLTC) system using genetically modified human cancer cells, followed by stimulation with the interleukin (IL)-2 plus immobilized anti-CD3 antibody (IL-2/CD3) system. A gastric cancer cell line, GC022588 (HLA-A2, 24, B35, 55, C1,3), was retrovirally transduced with the human interleukin (IL)-2 gene (GC/IL-2) or the neomycin-resistance gene (GC/Neo). The secretion of biologically active IL-2 was detectable in GC/IL-2 cells but not in GC/Neo or parental GC022588 cells. The cytotoxic activity against the parental GC022588 cells of peripheral blood mononuclear cells (PBMC) was greater among PBMC activated with MLTC using GC/IL-2 than among those activated with MLTC using GC/Neo or without MLTC. The IL-2/CD3 stimulation could efficiently expand the effector lymphocytes without any reduction of the cytotoxic activity generated. The cytotoxic activity generated by this system was reproducible in several HLA-A2- or A24-positive donors. The effector lymphocytes could kill the other adenocarcinoma cells expressing HLA-A2 or A24. The phenotypes of the effector lymphocytes generated with the system were 40% CD4+ and 70% CD8+. Both phenotypes may have been responsible for the cytotoxicity. The removal of adherent cells from PBMC before the MLTC did not affect the generation of cytotoxicity, whereas neutralization of tumor-derived IL-2 with a specific antibody during the MLTC significantly inhibited the generation of cytotoxicity. These results suggest that IL-2 gene-transduction augments the immunogenicity of the tumor cells that efficiently stimulate lymphocytes to be cytotoxic, and that the IL-2/CD3 system may be practical for the expansion of effector lymphocytes for use in adoptive immunotherapy for cancer. The mechanism by which IL-2 gene-modified tumor cells stimulate immune reactivity was discussed.

Adenocarcinoma↗
PubMed2002

Coordination dynamics of learning and transfer across different effector systems.

If different effector systems share a common task-specific coordination dynamics, transfer and generalization of sensorimotor learning are predicted. Subjects learned a visually specified phase relationship with either the arms or the legs. Coordination tendencies in both effector systems were evaluated before and after practice to detect attractive states of the coordination dynamics. Results indicated that learning a novel relative phase with a single effector system spontaneously transferred to the other, untrained effector system. Transfer was revealed not only as improvements in performance but also as modifications of each system's initial (prelearning) coordinative landscape. What is learned, appears to be a high-level but neurally instantiated dynamic representation of skilled behavior that proves to be largely effector independent, at least across anatomically symmetric limbs.

Adult↗
PubMed2003

Z-FA-fmk inhibits effector caspases but not initiator caspases 8 and 10, and demonstrates that novel anticancer retinoid-related molecules induce apoptosis via the intrinsic pathway.

Synthetic retinoid-related molecules (RRMs) have been described that show strong antiproliferative activity and induce apoptosis in cancer cells. These RRMs induce caspase activity independently of the retinoid receptors in Jurkat T cells. We observed that the inhibitor of cathepsins B and L Z-FA-fmk blocks the induction of DEVDase activity, DNA fragmentation, and externalization of phosphatidylserine by selective RRMs. Z-FA-fmk can inhibit caspase activity in vitro and selectively inhibits recombinant effector caspases 2, -3, -6, and -7. In contrast, purified initiator caspases 8 and 10 are not affected, whereas the apoptosome-associated caspase 9 is only partially inhibited by Z-FA-fmk in vitro. These data correlate with the covalent binding of biotinylated Z-FA-fmk to the active large subunit of effector caspases. This selective targeting of effector caspases is also observed in Jurkat cells and has been used to demonstrate that RRMs induce apoptosis through the mitochondrial pathway and activate caspase 8 in a Z-FA-fmk-sensitive manner. Thus, Z-FA-fmk fails to inhibit Fas-mediated activation of caspase 8, but completely inhibits RRM-induced processing of caspase 8. Z-FA-fmk does not prevent the autoproteolytic cleavage of caspase 9 in Jurkat cells and partially inhibits the processing and full maturation of effector caspases induced by the RRMs. Moreover, Z-VAD-fmk and Z-FA-fmk have no effect on the release of cytochrome c induced by the RRMs. Other cathepsin inhibitors elicit no effect on RRM-induced apoptosis in Jurkat cells, suggesting that caspases are the major effectors of RRM action.

Amino Acid Chloromethyl Ketones↗
PubMed1992

[Site-directed chemical restriction of a single-stranded DNA fragment by an alkylating derivative of the tetranucleotide d(pApGpCpA) in the presence of tetranucleotide effectors].

Alkylation of a single-stranded DNA 302-mer by a 5'-O-phosphoryl-[4-(N-2-chloroethyl-N-methylamino)benzyl]amide derivative of the tetradeoxyribonucleotide d(pApGpCpA) in the presence of 3',5'-di-N-(2-hydroxyethyl) phenazinium derivatives of tetranucleotides as effectors led to specific chemical cleavage of the target at the guanosine residues of the sites ... pTpGppT. The reagent can be selectively addressed to one of three alkylation sites with the aid of a pair of tetranucleotide effectors flanking the chemically reactive tetranucleotide in the complex with the target DNA. The yield of the cleavage depends on the concentration of both the reagent and effectors, and can be enhanced, if a chain of two or more effectors from each side of the reagent is used. In this case, 3',5'-di-Phn-tetranucleotide effectors are to immediately flank the reagent.

Alkylation↗
PubMed2003

(211)At-labeled and biotinylated effector molecules for pretargeted radioimmunotherapy using poly-L- and poly-D-Lysine as multicarriers.

Poly-L- and poly-D-lysine were evaluated as carriers of astatine and biotin for prospective use as effector molecules in pretargeted radioimmunotherapy of micrometastases. The precursor polylysine was derivatized in a three-step, single-pot procedure, including biotinylation with biotin amidocaproic N-hydroxysuccinimide, astatination via the intermediate reagent N-succinimidyl 3-(trimethylstannyl)benzoate, and, finally, charge modification using succinic anhydride. The chemistry was shown to be very facile, with a biotinylation efficiency of 75 +/- 5%, and overall radiochemical yields in the range of 50-70%. After charge modification, no amines could be detected in the final product. The biotin function was unaffected by the chemistry and the radiation, as confirmed by almost complete binding of the effector molecule to avidin beads using a convenient filter tube assay. The effector molecules were evaluated in tumor-free female nude mice with regard to whole-body retention and tissue distribution after i.p. administration. The distribution of the L-isomer effector molecule showed rapid whole-body clearance with low uptake in all tissues, whereas the D-isoform showed whole-body clearance related to uptake in the kidneys. Both D-isomer and L-isomer showed faster blood clearance and generally lower tissue uptakes than labeled antibodies. The normal tissue distribution after the peritoneal administration implies that pretargeting using L-structure polylysine as the effector molecule may give a higher therapeutic index than that achieved in conventional radioimmunotherapy.

Animals↗
PubMed1992

Cellular interactions in effector cell generation and tumor regression mediated by anti-CD3/interleukin 2-activated tumor-draining lymph node cells.

Previous studies have demonstrated that progressive growth of the weakly immunogenic MCA 106 murine sarcoma stimulated, in the draining lymph nodes, the production of tumor-sensitized but not fully functional preeffector lymphocytes. These lymphocytes could develop into specific immune effector cells after sequential in vitro activation with anti-CD3 monoclonal antibody and interleukin 2 (IL-2). In this study, we analyzed cellular requirements for in vivo sensitization of preeffector cells, for generation of immune effector cells by the method of anti-CD3/IL-2 activation, and for adoptive immunotherapy mediated by activated cells. By selective depletion of T-cell subsets in vivo, we found that tumor regression after systemic adoptive immunotherapy required the collaboration of activated CD4+ and CD8+ cells. It was further demonstrated that CD8+ immune cells alone could mediate antitumor effects if exogenous IL-2 was provided in vivo. These results suggest that CD8+ cells served as immediate effector cells, whereas CD4+ immune cells provided a helper function via the secretion of IL-2. During in vitro anti-CD3/IL-2 activation, generation of effector cells depended on the collaborative interaction between previously sensitized CD4+ and CD8+ preeffector cells. At the stage of in vitro activation, the addition of IL-2 could not substitute the function of CD4+ cells. We next examined whether the sensitization of preeffector cells in the draining lymph nodes required cellular interactions between CD4+ and CD8+ T-cells. By in vivo depletion of T-cell subsets during tumor growth, we found that CD4+ cells were sensitized independently of CD8+ cells. More interestingly, in vivo sensitization of CD8+ preeffector cells also occurred independently in the absence of a CD4+ helper cell response. The lack of T-cell-T-cell interactions in vivo may explain the failure of effector cell generation during progressive tumor growth. Taken together, these results demonstrate that the anti-CD3/IL-2 activation defines an immune response distinct from many previously described mechanisms of antitumor immune responses.

Animals↗
PubMedDate not supplied

[Kinetic analysis of the influence of inverse effectors (inhibitors and activators) on enzymatic (transport) activity of proteins].

The method is proposed for calculation of the most important parameters of the two-stage enzymatic or transport process--modification factors alpha and beta (which characterize the effector action mechanism) as well as the inhibition constant K(i) or activation constant K(a) (characterize the effector affinity for protein). The method was derived as based on the analysis of kinetic regularities of the action of reversible effectors (inhibitors and activators) on the catalytic (transport) activity of proteins. The method is based on the titration of enzymatic (transport) protein by the substrate with the absence and with presence of the effector taken in one of concentrations as well as determination (under the fixed substrate concentration) of the inhibition coefficient i(0.5) (in case of the inhibitor action) or the activation coefficient a(0.5) (in case of the activator action). Practical use of the method has been demonstrated on the example of reversible inhibition to eosine Y (2', 4', 5', 7' - tetrabromofluorescein) ofthe reaction of enzymatic hydrolysis of ATP catalyzed by highly purified transport Ca2+, Mg(2+)-ATPase isolated from the smooth-muscle sarcolemma. In this case the inhibitory effect is characterized by the following parameters: alpha = 6-8 > 1; beta = 0.50-0.53 < 1; inhibition constant K(i) = 10(-9) - 10(-8) M. Consequently, judging from the values of alpha and beta, the eosine Y effect on the analyzed Ca2+, Mg(2+)-dependent ATP-hydrolase enzymatic reaction is based on the mechanism of the mixed inhibition (one can observe the inhibition of the both stages of enzymatic transformation--the substrate binding with the enzyme and decomposition of "Michaelis complex" in the direction of formation of the reaction products). The inhibitor itself, in correspondence with K(ij) values is characterized by rather high affinity for Ca2+, Mg(2+)-ATPase. It is supposed that the proposed approach can be useful when identifying the type of the reversible effector action on the enzymatic (transport) activity of proteins, estimation of real affinity of the inhibitors and activators for the latter.

Enzyme Activators↗