Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Thymidylate kinase derived from the blast cells of human chronic myelocytic leukemia was purified 2186-fold to near homogeneity by means of alcohol precipitation, alumina-Cgamma gel fractionation, calcium phosphate gel fraction, ultrafiltration, and affinity column chromatography. The molecular weight was estimated by glycerol gradient centrifugation to be 50,000. This enzyme had an optimal activity at pH 7.1 and required a divalent cation in order to catalyze the reaction. Mg2+ and Mn2+ were found to be the preferential divalent cations. The activation energy was estimated to be 19.1 kcal/mol at pH 7.2. Initial velocity study suggested that the reaction followed a sequential mechanism. Mg2+ ATP had a Km of 0.25 mM and dTMP had a Km of 40 micrometer. The enzyme was unstable even at 4 degrees. In the presence of ATP or dTMP the enzyme maintained its activity. Purine triphosphate nucleosides were found to be better phosphate donors than the pyrimidine triphosphate nucleosides. ATP and dATP had a lower Km and a higher Vmax than GTP and dGTP. dTMP was the only preferred phosphate receptor among all the monophosphate nucleotides tested dTTP and IdUTP competed with both substrates and inhibited the reaction with a Ki of 0.75 mM and 1.1 mM, respectively.
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PMID:Human thymidylate kinase. Purification, characterization, and kinetic behavior of the thymidylate kinase derived from chronic myelocytic leukemia. 1 69

Actin, myosin, and a high molecular weight actin-binding protein were purified from chronic myelogenous leukemia (CML) leukocytes. CML leukocyte actin resembled skeletal muscle and other cytoplasmic actins by its subunit molecular weight, by its ability to polymerize in the presence of salts, and to activate the Mg2+-ATPase activity of rabbit skeletal muscle myosin. CML leukocyte myosin was similar to other vertebrate cytoplasmic myosins in having heavy chains and two light subunits. However, its apparent heavy-chain molecular weight and Stokes radius suggested that it was variably degraded during purification. Purified CML leukocyte myosin had average specific EDTA- AND Ca2+-activated ATPase activities of 125 and 151 nmol Pi released/mg protein per min, respectively and low specific Mg2+-ATPase activity. The Mg2+-ATPase activity of CML myosin was increased 200-fold by rabbit skeletal muscle F-actin, but the specific activity relative to that of actin-activated rabbit skeletal muscle myosin was low. CML leukocyte myosin, like other vertebrate cytoplasmic myosins, formed filaments in 0.1 M KCl solutions. Reduced and denatured CML leukocyte-actin-binding protein had a single high molecular weight subunit like a recently described actin-binding protein of rabbit pulmonary macrophages which promotes the polymerization and gelation of actin. Cytoplasmic extracts of CML leukocytes prepared with ice-cold 0.34-M sucrose solutions containing Mg2+-ATP, dithiothreitol, and EDTA at pH 7.0 underwent rapid gelation when warmed to 25 degrees C. Initially, the gel could be liquified by cooling to ice-bath temperature. With time, warmed cytoplasmic extract gels shrunk ("contracted") into aggregates. The following findings indicated that CML leukocyte actin-binding protein promoted the temperature-dependent gelation of actin in the cytoplasmic extracts and that CML leukocyte myosin was involved in the contraction of the actin gels: (a) Cytoplasmic extract gels initially contained actin as their major polypeptide component and consistent of tangled thin filaments; (b) Contracted aggregates of cytoplasmic extract gels contained by large quantities of myosin as well as actin; (c) Purified actin-binding protein underwent a temperature-dependent, reversible aggregation and caused low concentrations of purified muscle or CML leukocyte actins to gel in sucrose solutions; (d) The gels formed from purified actin plus purified actin-binding protein slowly contracted in the presence but not in the absence of purified CML leukocyte myosin; (e) Rabbit antiserum against purified CML leukocyte actin-binding protein but not against purified CML leukocyte myosin inhibited the gelation of warmed CML leukocyte extracts. Antiserum against CML leukocyte myosin had no effect on the gelation of CML leukocyte extracts but partially curtailed the contraction of the CML leukocyte extract gels and of gels formed from purified CML leukocyte actin-binding protein plus rabbit skeletal muscle actin.
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PMID:Interactions of actin, myosin, and an actin-binding protein of chronic myelogenous leukemia leukocytes. 13 21

Normal human granulocytes obtained by Ficoll-Hypaque sedimentation were subjected to mild hypotonic shock and disruption by shear. The homogenate was fractionated by differential centrifugation and equilibrium ultracentrifugation to yield a plasma membrane preparation constituting 1% of the total cellular protein and enriched fifteen- and six-fold in alkaline phosphatase and Mg2+-adenosine triphosphatase activities, respectively. Granulocytes obtained from patients with chronic myeloid leukemia (CML) were identically processed. The protein constituents of both the normal and CML granulocyte plasma membranes were resolved by two-dimensional polyacrylamide gel electrophoresis. Comparison of the stained gels revealed CML-associated quantitative changes in four out of the fifteen protein spots examined. Thus, this analysis has permitted identification of those protein moieties that deserve attention for further isolation and purification.
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PMID:Plasma membranes from normal and chronic myeloid leukemic granulocytes: isolation and two-dimensional polyacrylamide gel electrophoretic analysis. 385 66

A folate binding protein purified from the cytoplasm of human chronic myelogenous leukemia cells and saturated with [3H]pteroylglutamic acid, and the same protein labeled with 125I and saturated with pteroylglutamic acid, binds to the nuclear fraction of rat liver. EDTA inhibits this binding and this inhibition is reversed by Ca2+ but not by Mg2+. The nuclear fraction binds very little free [3H]pteroylglutamic acid, and the cytoplasm from which the nuclei have been removed does not bind the protein-folate complex. A Kd of 0.7 nM and a value of 1000 unsaturated binding sites per nucleus were obtained by Scatchard analysis. The translocation of folate to the nuclear membrane or nucleus by this soluble cytoplasmic folate binder may be the mechanism for the induction of enzyme(s) required for the metabolism of the folate ligand attached to the protein.
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PMID:Rat liver nuclei contain receptors for a folate binding protein. 632 Feb 2

A lectin, Crenomytilus grayanus (CGL), was purified from sea mussel C. grayanus by affinity chromatography on acid-treated Sepharose 6B and following gel filtration on Sephacryl S-200. Molecular weight of the lectin obtained was determined by SDS-PAGE to be 18,000, independent of the presence or absence of beta-mercaptoethanol. CGL was found to agglutinate all types of the human erythrocytes together with mouse and rabbit. In hemagglutination inhibition assays, N-acetyl-D-galactosamine, D-galactose, and D-talose were the most potent inhibitors among the monosaccharides tested. Out of the oligosaccharides containing nonreducing terminal D-galactose, melibiose, and raffinose were found to be strong inhibitors. On the other hand, among the glycoproteins, asialo-BSM was the best inhibitor. The hemagglutinating activity of CGL was independent of the divalent cations Ca2+ and Mg2+. Significant CGL activity was observed between pH 8-10.
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PMID:Isolation and characterization of new GalNAc/Gal-specific lectin from the sea mussel Crenomytilus grayanus. 956 72

We have constructed an allosterically controllable novel enzyme (designated maxizyme) that can be transcribed in vivo under the control of a human tRNA(Val) promoter. The maxizyme has sensor arms that can recognize target sequences, and in the presence of such a target sequence only, it can form a cavity that can capture catalytically indispensable Mg2+ ions. As a target for a demonstration of the potential utility of the maxizyme, we chose BCR-ABL mRNA, the translated products of which cause chronic myelogenous leukemia. Only the maxizyme (but not conventional ribozymes) had extremely high specificity and high-level activity, not only in vitro but also in cultured cells including BV173 cells derived from a patient with a Philadelphia chromosome. The maxizyme induced apoptosis only in leukemic cells with this chromosome.
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PMID:A novel allosterically trans-activated ribozyme, the maxizyme, with exceptional specificity in vitro and in vivo. 984 34

The protein encoded by chimeric BCR-ABL mRNA causes chronic myelogenous leukemia (CML). We showed previously that a novel allosterically controllable ribozyme, of the type known as a maxizyme, can cleave this mRNA, with high specificity and high-level activity in vivo. We designed the maxizyme in such a way that it was able to form an active core with which to capture the catalytically indispensable Mg2+ ions only in the presence of the BCR-ABL mRNA junction. In order to probe the putative conformational changes, we used a weakly alkaline solution (pH 9.2) in the presence of 25 mM Mg2+ ions to hydrolyze differentially phosphodiester bonds that were located in different environments. Phosphodiester bonds in single-stranded regions were clearly more susceptible to attack by alkali than those within a double-stranded helix. As indicated by earlier data obtained in vivo, our results demonstrated that the active conformation was achieved only in the presence of the junction within the chimeric BCR-ABL mRNA. Moreover, we demonstrated that the use of mild alkaline solutions to probe RNA structures is very informative.
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PMID:Chemical and enzymatic probing of effector-mediated changes in the conformation of a maxizyme. 1085 5

We demonstrated previously that an allosterically controllable novel ribozyme, designated the maxizyme, is a powerful tool for disruption of an abnormal chimeric RNA target [BCR-ABL (b2a2) mRNA], and we proposed that it might provide the basis for future gene therapy for the treatment of chronic myelogenous leukemia (Kuwabara et al. Mol. Cell 1998, 2, 617-627). The maxizyme has sensor arms that can recognize a specific sequence and, in the presence exclusively of such a specific sequence, it can form a cavity for capture of catalytically indispensable Mg2+ ions. Cleavage of the target RNA then occurs at a site distant from the specific sequence. Clearly, the specific sequences recognized by sensor arms should not be limited to those of the above mentioned abnormal chimeric target. Thus, to demonstrate the general applicability of maxizyme technology, we constructed maxizymes targeted to other mRNAs, such as PML-RAR alpha mRNA, sDLST mRNA, and BCR-ABL (b1a2) mRNA, that are not cleaved with high specificity by the wild-type hammerhead ribozyme. Specific and efficient cleavage in vitro of these mRNAs by the custom-designed maxizymes demonstrated clearly that maxizyme technology is not limited to a specific case but may have broad general applicability in molecular biology and, also, in a clinical setting.
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PMID:Maxizymes, novel allosterically controllable ribozymes, can be designed to cleave various substrates. 1170 32

Protein kinases play a predominant regulatory role in nearly every aspect of cell biology and they can modify the function of a protein in almost every conceivable way. Protein phosphorylation can increase or decrease enzyme activity and it can alter other biological activities such as transcription and translation. Moreover, some phosphorylation sites on a given protein are stimulatory while others are inhibitory. The human protein kinase gene family consists of 518 members along with 106 pseudogenes. Furthermore, about 50 of the 518 gene products lack important catalytic residues and are called protein pseudokinases. The non-catalytic allosteric interaction of protein kinases and pseudokinases with other proteins has added an important regulatory feature to the biochemistry and cell biology of the protein kinase superfamily. With rare exceptions, a divalent cation such as Mg2+ is required for the reaction. All protein kinases exist in a basal state and are activated only as necessary by divergent regulatory stimuli. The mechanisms for switching between dormant and active protein kinases can be intricate. Phosphorylase kinase was the first protein kinase to be characterized biochemically and the mechanism of its regulation led to the discovery of cAMP-dependent protein kinase (protein kinase A, or PKA), which catalyzes the phosphorylation and activation of phosphorylase kinase. This was the first protein kinase cascade or signaling module to be elucidated. The epidermal growth factor receptor-Ras-Raf-MEK-ERK signaling module contains protein-tyrosine, protein-serine/threonine, and dual specificity protein kinases. PKA has served as a prototype of this enzyme family and more is known about this enzyme than any other protein kinase. The inactive PKA holoenzyme consists of two regulatory and two catalytic subunits. After binding four molecules of cAMP, the holoenzyme dissociates into a regulatory subunit dimer (each monomer binds two cAMP) and two free and active catalytic subunits. PKA and all other protein kinase domains have a small amino-terminal lobe and large carboxyterminal lobe as determined by X-ray crystallography. The N-lobe and C-lobe form a cleft that serves as a docking site for MgATP. Nearly all active protein kinases contain a K/E/D/D signature sequence that plays important structural and catalytic roles. Protein kinases contain hydrophobic catalytic and regulatory spines and collateral shell residues that are required to assemble the active enzyme. There are two general kinds of conformational changes associated with most protein kinases. The first conformational change involves the formation of an intact regulatory spine to form an active enzyme. The second conformational change occurs in active kinases as they toggle between open and closed conformations during their catalytic cycles. Because mutations and dysregulation of protein kinases play causal roles in human disease, this family of enzymes has become one of the most important drug targets over the past two decades. Imatinib was approved by the United States FDA for the treatment of chronic myelogenous leukemia in 2001; this small molecule inhibits the BCR-Abl protein kinase oncoprotein that results from the formation of the Philadelphia chromosome. More than two dozen other orally effective mechanism-based small molecule protein kinase inhibitors have been subsequently approved by the FDA. These drugs bind to the ATP-binding site of their target enzymes and extend into nearby hydrophobic pockets. Most of these protein kinase inhibitors prolong survival in cancer patients only weeks or months longer than standard cytotoxic therapies. In contrast, the clinical effectiveness of imatinib against chronic myelogenous leukemia is vastly superior to that of any other targeted protein kinase inhibitor with overall survival lasting a decade or more. However, the near universal and expected development of drug resistance in the treatment of neoplastic disorders requires new approaches to solve this therapeutic challenge. Cancer is the predominant indication for these drugs, but disease targets are increasing. For example, we can expect the approval of new drugs inhibiting other protein kinases in the treatment of illnesses such as hypertension, Parkinson's disease, and autoimmune diseases.
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PMID:A historical overview of protein kinases and their targeted small molecule inhibitors. 2620 88