Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific modification of the monomeric fraction III of ferri-hemoglobin from insect larvae Chironomus thummi thummi (Hb CTT) was studied on histidyl residues His-G19 (pK 4,8), His-E5 (pK 7,3) and Met-H22 at different pH using iodacetamide and spin label 2,2,6,6-tetramethyl-4-bromacethyl-piperidin-1-oxyl, an analogue of bromacetate. The analysis of the products of carboxymethylation (CM) showed that at pH 5,0 two products of modification CM-(His-G19)-Hb CTT, and CM-(Met-H22)-Hb CTT were obtained. In the case of modification at pH 7,2 with a spin label dicarboxymethylatid product CM-(His-G19)-CM (His-E5)-Hb CTT is obtained. In all products the degree of modification was one spin label per mole protein. Based on the data on the primery and tertiary structures Hb CTT and the results of the investigation, different reactivity of His-G19 and His-E5, as well as the cause of the absence of the product of carboxymethylation on His-G2 have been discussed. By analizing the absorption spectra of carboxymethylated derivatives of hemoglobin in the ultraviolet and visible region, as well as from the pH dependence curves of the absorption at Soret band in the interval pH 5,5-11,5 it has been shown that carboxymethylation of His-G19 and His E5 is not accompanied by any substantial disturbance of the structures of aquous-complexes Hb CTT. Modification of Met-H22 leads to strong changes in the absorption spectrum and to the absence of pH dependence of the absorption at Soret band, which indicates a change in the aquous-complexes Hb CTT structure.
Mol Biol (Mosk)
PMID:[Selected carboxymethylation of ferri-hemoglobin from insect larvae Chironomus thummi thummi]. 17 63

The protein synthesis initiation factor eIF-3 (a multicomponent protein complex) was labelled with 32P by phosphorylation with a protein kinase present in a partially purified 'hemin-controlled repressor' preparation. The interaction of the labelled factor with the 40 S ribosomal subunit during the course of initiation was followed. It binds to the 40 S subunit in the absence of other initiation factors and inhibits the Mg2+-dependent reassociation of the 40 S with the 60 S ribosomal subunit. It stimulates the binding of the ternary complex (eIF-2, GTP, Met-tRNAf) to the 40 S subunit, and earlier work (Trachsel, H., Schreier, M.H., Erni, B. and Staehelin, T. (1977) J. Mol. Biol. 116, 745-767) also showed it to be essential for the subsequent binding of mRNA. The factor is released from the 40 S initiation complex during the 60 S subunit joining reaction.
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PMID:Initiation of mammalian protein synthesis. The multiple functions of the initiation factor eIF-3. 51 82

A comparative study of the position specificity of tRNA-methylases from normal and tumour tissues was performed on yeast tRNA1Val as the substrates using partially purified enzyme preparations from rat kidney and carcinoma RA. As in the case of rat liver and Novikoff hepatoma, two methylated compounds are formed in yeast tRNA1Val under the action of rat kidney and carcinoma enzyme preparations: m5C is formed in the sequence C49--C52 located in the extra loop and A59 in the Tpsi-loop is is converted into m1A. The activity of m5C-methylase [S-Ado-Met-tRNA-(cytosine-5)methyltransferase] (E. C. 2.1.1.29) is approximately equal in both tissues, whereas the activity of m1A-methylase [S-Ado-Met-tRNA-(adenine-1)methyltransferase] (E. C. 2.1.1.36) in carcinoma is twice as high as in the kidney. The two enzymes do not differ in their position specificity.
Mol Biol (Mosk)
PMID:[Comparative study of the tRNA-methylases of normal and tumor tissues. II. Positional specificity of renal and carcinoma RA methylases]. 61 46

The mode and site of action of inhibitors of translation (initiation, elongation and termination of protein synthesis) in eukaryotic systems is reviewed. The isolation and characterization of a factor is described that binds Ac-Phe-tRNA to form a complex made up of binding factors, Ac-Phe-tRNA, and ribosome. The binding of Ac-Phe-tRNA probably occurs at the ribosomal site involved in the binding of the initiator substrate Met-tRNAF. The effect of inhibitors of the intitiation phase of protein synthesis on the nonenzymic Ac-Phe-tRNA binding to ribosomes is investigated. The two sites translocation model for translation in eukaryotic cells is presented and the effects of inhibitors on the various steps of protein synthesis are determined empirically. The site of action of inhibitors of peptide bond formation at the ribosomal peptidyl transferase center is elucidated. The action of inhibitors of translocation is sutdied in model cell-free systems from human cells. In addition, a number of methylxanthines are shown to enhance the elongation phase in polypeptide synthesis by stimulating the enzymic binding of aminoacyl-tRNA. The effect of caffeine, theophylline and its derivatives are shown to be fairly specific and dependent on the ribosome concentration. Aminophylline is shown to have a similar effect but also enhances aminoacyl-tRNA synthetase activity at low Mg++ concentrations, probably displacing the optimal concentration of Mg++ in the reaction. This second effect of aminophylline appears to be due to the ethylenediamine moiety of aminophylline since it is also observed in the presence of different polyamines but not in the presence of caffeine or theophylline.
Mol Cell Biochem 1976 Feb 16
PMID:Antibiotics and compounds affecting tanslation by eukaryotic ribosomes. Specific enhancement of aminoacyl-tRNA binding by methylaxnthines. 76 41

The action of S-adenosyl-l-homocysteine (S-Ado-Hcy), its four structural analogues S-Ino-Hcy, S-Guo-Hcy, S-Urd-Hcy, S-Cyd-Hcy and the five corresponding sulfoxides on tRNA methylases has been investigated. The data obtained in the study of overall incorporation of 14CH3-groups into an unfractioned tRNA preparation suggested that both the affinity of the inhibitors tested for various methylases and the type of inhibition were different. The experiments performed with unfractioned tRNA preparation permit to get an idea of the average inhibitory potency of each of the compounds. The study of their action on individual tRNA methylases by means of fractionation of minor components produced demonstrated that the affinity of the inhibitors tested for various methylases was really different. Thus, S-Ado-Hcy, S-Ino-Hcy and S-Urd-Hcy practically do not inhibit m1A methylase but have the highest affinity for m5C methylase. In an experiment with tRNAPhe which is a substrate for a single, namely m5C methylase, the type of inhibition of this methylase by S-Cyd-Hcy was revealed; it was found to be non-competitive with respect to S-Ado-Met, and the S-Cyd-Hcy concentration reducing the methylation by 50 percent was 1.2-10(-4) M.
Mol Biol (Mosk)
PMID:[Inhibiting effect of S-adenosyl-L-homocysteine and its structural analogs on the process of enzymatic methylation of tRNA]. 78 40

The in vitro B. subtilis protein synthesizing system is very restricted in its ability to translate E. coli phage messenger RNA's, specifically phage T4 RNA, even though it actively translates its proper mRNA species. In contrast, the E. coli system translates with similar efficiency mRNA from either source. The initiation factors from the two systems are functionally interchangeable. The 30S B. subtilis ribosomal subunit is responsible for the limited template specificity of the B. subtilis ribosomes. Although the efficiency of the T4RNA directed F Met-tRNA binding by B. subtilis ribosomes is less than that of SPOI RNA-directed binding, the most restrictive step in the translation of T4RNA by B. subtilis ribosomes appears to be at the level of the formation of the first peptide bond, as measured by F Metpuromycin formation.
Mol Gen Genet 1976 Dec 31
PMID:Selective messenger translation by Bacillus subtilis ribosomes. 81 1

Rat liver ribosome treatment with ethanol and 1 M NH4Cl releases some 31-33 ribosomal proteins. This split protein fraction binds Phe-tRNA, Ac-Phe-tRNA, Met-tRNAM and f-Met-tRNAF in the absence of K+ and Mg++ ions. When the split protein fraction is passed through Sephadex G-100 only six proteins are retained in the column: S10, S14, S15, S19, L35, and L36. The aminoacyl-tRNA binding activity of this protein fraction retained in the Sephadex G-100 column is similar to that of the total split protein fraction, suggesting that the above six proteins, or only some of them, are involved in the binding reaction.
Mol Biol Rep 1976 Jul
PMID:Binding of aminoacyl-tRNA to rat liver ribosomal proteins. 95 16

We find that specific oxidation for the Met-192 residue in delta-chymotrypsin to methionine sulfoxide results in a twofold increase in Km(app) and unchanged kcat in the hydrolysis of N-acetyl mono(amino acid) amide substrates. However, the catalyzed hydrolyses of N-acetyl dipeptide amide substrates by (methionine sulfoxide)-192-delta-chymotrypsin (MS-delta-Cht) shows a four- to fivefold decrease in kcat and unchanged Km(app) with respect to delta-chymotrypsin. Hydrolysis of alpha-casein by MS-delta-Cht shows a similar 4.2-fold decrease in kcat. These results imply that the Met-192 acts differently with substrates that bind only in the primary, S1, binding site (i.e., AcPheNH2) from those that bind to more extended regions of the enzyme active site. In the binding of c+AcPheNH2 and AcTrpNH2, the results support a mechanism in which the Met-192 acts to slow the rate of sustrate dissociation from the Michaelis complex to free substrate and enzyme. This is in agreement with the x-ray crystallographic structure of dioxane inhibited alpha-chymotrypsin (Steitz, T., et al. (1969), J. Mol. Biol. 46, 337). However, this mechanism is not apparent when peptide and protein substrates bind. The decrease in kcat on Met-192 modification of approximately fivefold in the hydrolysis of polypeptide substrates show a small, but significant, catalytic contribution of the Met-192 toward the lowering of the energy of activation polypeptide substrate hydrolysis by chymotrypsin. This may support the crystallographic model of Fersht et al. (Fersht, A., et al. (1973), Biochemistry 12, 2035) in which it is proposed that the Met-192 participates in the distortion of bound polypeptide substrates toward the reaction transition-state configuration and, thus, plays a role in catalysis. However, if this mechanism occurs, the effect is small, only contributing about 1 kcal/mol to the lowering of the reaction activation energy.
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PMID:The role of methionine-192 of the chymotrypsin active site in the binding and catalysis of mono(amino acid) and peptide substrates. 96 30

Three mutants of Salmonella typhimurium LT2, which required either pantothenate or beta-alanine for growth, were obtained after treatment with N-methyl-N'-nitro-N-nitrosoguanidine. Their phenotype was: SM30 Pan-, SM31 Pan- Met-, SM32 Pan- Thi- (requirement for the thiazole-moiety of thiamine). Neither aspartate, dihydrouracil, nor beta-ureidopropionate replaced beta-alanine as growth factor. By conjugation it was found that the three genetic lesions (Pan-, Met-, Thi-) were located at about minute 128 of the bacterial chromosome. By transduction 63% linkage was found between the Pan and Met loci, and 84% between the Thi and Pan loci. Probably the thiazole auxotrophy was due to a lesion in the thiG locus. The new genetic locus responsible for the synthesis of beta-alanine was named panD.
Mol Gen Genet 1975 Sep 29
PMID:panD, a new chromosomal locus of Salmonella typhimurium for the biosynthesis of beta-alanine. 110 56

The contacts between bulky hydrophobic side chains (Val, Leu, Ile, Met, Phe, Tyr, and Trp) were studied in five globins with known three-dimensional structures. It is shown that a large majority of these side chains participate in such contacts, where most often one side chain makes contact with two to four nearby side chains. The "recognition element" of a helical region is most often a pair of bulky hydrophobic side chains belinging to neighboring turns of an alpha-helix. Such pairs most often make contact with bulky hydrophobic side chains brought in from the outside. An analysis is made of contacts between the hydrophobic side chains common to all five globins. It is shown that as a rule the most intense contacts in each globin are also common to the five globins. The role of these invariant contacts in the formation of the tertiary structure of globin molecules is considered. A suggestion is made that the apoglobin molecule consists of independently self-organizing halves, the internal structure of which is less subject to fluctuation than their mutual arrangement.
Mol Biol 1975 Jan
PMID:The structure of hydrophobic cores of globins. 112 3


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