Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: CAS:56-41-7 (alanine)
 70,945 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The p34cdc2 protein kinase is a component of maturation-promoting factor, the master regulator of the cell cycle in all eukaryotes. The activity of p34cdc2 is itself tightly regulated by phosphorylation and dephosphorylation. Predicted regulatory phosphorylation sites of Xenopus p34cdc2 were mutated in vitro, and in vitro-transcribed RNAs were injected into Xenopus oocytes. The cdc2 single mutants Thr-14----Ala and Tyr-15----Phe did not induce germinal vesicle breakdown (BVBD) upon microinjection into oocytes. In contrast, the cdc2 double mutant Ala-14/Phe-15 did induce GVBD. Both the Ala-14 and Ala-14/Phe-15p34cdc2 mutants were shown to coimmunoprecipitate cyclin B1 and to phosphorylate histone H1 in immune complex kinase assays. Microinjection of antisense oligonucleotides to c-mosXe was used to demonstrate the role of mos protein synthesis in the induction of GVBD by the Ala-14/Phe-15 cdc2 mutant. Thr-161 was also mutated. p34cdc2 single mutants Ala-161 and Glu-161 and triple mutants Ala-14/Phe-15/Ala-161 and Ala-14/Phe-15/Glu-161 failed to induce GVBD in oocytes and showed a decreased binding to cyclin B1 in coimmunoprecipitations. Each of the cdc2 mutants was also assayed by coinjection with cyclin B1 or c-mosXe RNA into oocytes. Several of the cdc2 mutants were found to affect the kinetics of cyclin B1 and/or mos-induced GVBD upon coinjection, although none affected the rate of progesterone-induced maturation. We demonstrate here the significance of Thr-14, Tyr-15, and Thr-161 of p34cdc2 in Xenopus oocyte maturation. In addition, these results suggest a regulatory role for mosXe in induction of oocyte maturation by the cdc2 mutant Ala-14/Phe-15.
Mol Cell Biol 1992 Jul
PMID:Requirement of mosXe protein kinase for meiotic maturation of Xenopus oocytes induced by a cdc2 mutant lacking regulatory phosphorylation sites. 137 75

Legionella pneumophila is an intracellular parasite which is able to survive and multiply in human monocytes and alveolar macrophages. The Mip (macrophage infectivity potentiator) protein has been shown to be an essential virulence factor. A search of translated nucleic acid data bases has shown that the Mip protein from strain Wadsworth possesses regions homologous to those found in the FK506-binding proteins (FKBPs) of several different eukaryotic organisms. FKBPs are able to bind to the immunosuppressant macrolide FK506 and possess peptidyl-prolyl cis/trans isomerase (PPIase) activity. The gene coding for the Mip protein was cloned from the chromosome of L. pneumophila strain Philadelphia I and sequenced. It was synthesized in Escherichia coli K-12 and after purification it exhibited PPIase activity catalysing the slow cis/trans isomerization of prolyl peptide bonds in oligopeptides. Mip is inhibited by FK506 and fully resistant to cyclosporin A, as was also found for the recently characterized FKBP-type PPIases of eukaryotes. However, the N-terminal extension of Mip and/or the substitutions of the variable amino acids in the C-terminal FKBP core leads to variations, when compared with eukaryotic FKBPs, in substrate specificity with the oligopeptide substrates of type Suc-Ala-Xaa-Pro-Phe-4-nitroanilide. Nevertheless, the Legionella Mip factor represents a bacterial gene product which shares some characteristics normally found in eukaryotic proteins. In view of the activity of PPIases in protein-folding reactions, such prokaryotic FKBP analogues may represent a new class of bacterial pathogenicity factors.
Mol Microbiol 1992 May
PMID:Mip protein of Legionella pneumophila exhibits peptidyl-prolyl-cis/trans isomerase (PPlase) activity. 137 19

Photochemically induced dynamic nuclear polarization (photoCIDNP) measurements, specific for exposed tyrosine residues, have been applied to elucidate conformational differences responsible for the immunological diversity of the synthetic multichain copolymers, Tyr1Tyr2Glu3Glu4-poly-DL-Ala-poly-Lys and Tyr1Glu2Tyr3Glu4-poly-DL-Ala-poly-LS. These two copolymers are essentially identical in their molecular weight, size, shape and composition, and differ only in the order of the two internal amino acid residues within the sequence of the tetrapeptide epitopes. Nonetheless, previous studies have shown that the two macromolecules behave differently, as evidenced by their immunological and immunogenic properties. As immunogens they act under different genetic control mechanisms, and differ in their interactions with antigen presenting cells, T cells and B cells. Antibodies elicited against these two antigens do not cross react. The photoCIDNP measurements of these two polymers, intended to elucidate discrete structural differences controlling immune recognition, showed that in the TyrTyrGluGlu polymer, Tyr1 and Tyr2 rings are free, non-interacting and undergo fast internal rotation. Computed minimum energy conformations confirm these conclusions and indicate that Tyr1 and Tyr2 point to different regions in space. In TyrGluTyrGlu, however, CIDNP measurements give rise to one broad tyrosine 3,5 proton signal, the result of a strong Tyr1-Tyr3 hydrophobic interaction. These two tyrosine residues are thus close in space, and undergo slow internal rotation. These results are in agreement with the computed minimum energy conformations.
Mol Immunol 1992 Sep
PMID:Structural origin of the immunological diversity of two closely related tetrapeptides: CIDNP study of TyrTyrGluGlu and TyrGluTyrGlu epitopes. 137 76

A comprehensive mutational analysis was used to analyze the side-chains on human growth hormone (hGH) important for binding 21 different anti-hGH mouse monoclonal antibodies (MAbs) whose equivalent concentrations for 50% binding (EC50) ranged from approximately 10(7) to 3 x 10(10) M-1. A combination of homolog- and alanine-scanning mutagenesis coupled with a robot-aided enzyme-linked immunosorbent assay were used to create high resolution "functional epitopes" for each MAb. Every functional epitope mapped to at least two polypeptide segments of hGH that were close together in the folded protein to form a patch. Although these patches sometimes overlapped, each was different indicating no two MAbs bound identically to hGH. The MAbs bound to determinants in loops and helices that were generally most accessible to a 9 A radius probe. Only a few side-chains dominated each functional epitope and these tended to be Arg greater than Pro greater than Glu approximately Asp approximately Phe approximately Ile (Ala, Cys and Trp were not tested). Our studies indicate that most of the accessible surface of hGH is potentially antigenic in the mouse and suggest that functional epitopes are dominated by fewer side-chains than may be in the contact epitope.
J Mol Biol 1992 Aug 05
PMID:High resolution functional analysis of antibody-antigen interactions. 138 May 63

The crystal structures of three mutant hemoglobins reconstituted from recombinant beta chains and authentic human alpha chains have been determined in the deoxy state at 1.8-A resolution. The primary structures of the mutant hemoglobins differ at the beta-chain amino terminus. One mutant, beta Met, is characterized by the addition of a methionine at the amino terminus. The other two hemoglobins are characterized by substitution of Val 1 beta with either a methionine, beta V1M, or an alanine, beta V1A. All the mutation-induced structural perturbations are small intrasubunit changes that are localized to the immediate vicinity of the beta-chain amino terminus. In the beta Met and beta V1A mutants, the mobility of the beta-chain amino terminus increases and the electron density of an associated inorganic anion is decreased. In contrast, the beta-chain amino terminus of the beta V1M mutant becomes less mobile, and the inorganic anion binds with increased affinity. These structural differences can be correlated with functional data for the mutant hemoglobins [Doyle, M. L., Lew, G., DeYoung, A., Kwiatkowski, L., Noble, R. W., & Ackers, G. K. (1992) Biochemistry preceding paper is this issue] as well as with the properties of ruminant hemoglobins and a mechanism [Perutz, M., & Imai, K. (1980) J. Mol. Biol. 136, 183-191] that relates the intrasubunit interactions of the beta-chain amino terminus to changes in oxygen affinity. Since the structures of the mutant deoxyhemoglobins show only subtle differences from the structure of deoxyhemoglobin A, it is concluded that any of the three hemoglobins could probably function as a surrogate for hemoglobin A.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:High-resolution X-ray study of deoxy recombinant human hemoglobins synthesized from beta-globins having mutated amino termini. 139 Jun 48

The importance of amino acid side-chains in helix stability has been investigated by making a series of mutations at the N-caps, C-caps and internal positions of the solvent-exposed faces of the two alpha-helices of barnase. There is a strong positional and context dependence of the effect of a particular amino acid on stability. Correlations have been found that provide insight into the physical basis of helix stabilization. The relative effects of Ala and Gly (or Ser) may be rationalized on the basis of solvent-accessible surface areas: burial of hydrophobic surface stabilizes the protein as does exposure to solvent of unpaired hydrogen bond donors or acceptors in the protein. There is a good correlation between the relative stabilizing effects of Ala and Gly at internal positions with the total change in solvent-accessible hydrophobic surface area of the folded protein on mutation of Ala----Gly. The relationship may be extended to the N and C-caps by including an extra term in hydrophilic surface area for the solvent exposure of the non-intramolecularly hydrogen-bonded main-chain CO, NH or protein side-chain hydrogen bonding groups. The requirement for solvent exposure of the C-cap main-chain CO groups may account for the strong preference for residues having positive phi and psi angles at this position, since this alpha L-conformation results in the largest solvent exposure of the C-terminal CO groups. Glycine in an alpha L-conformation results in the greatest exposure of these CO groups. Further, the side-chains of His, Asn, Arg and Lys may, with positive phi and psi-angles, form a hydrogen bond with the backbone CO of residue in position C -3 (residues are numbered relative to the C-cap). The preferences at the C-cap are Gly much greater than His greater than Asn greater than Arg greater than Lys greater than Ala approximately Ser approximately greater than Asp. The preferences at the N-cap are determined by hydrogen bonding of side-chains or solvent to the exposed backbone NH groups and are: Thr approximately Asp approximately Ser greater than Gly approximately Asn greater than Gln approximately Glu approximately His greater than Ala greater than Val much greater than Pro. These general trends may be obscured when mutation allows another side-chain to become a surrogate cap.(ABSTRACT TRUNCATED AT 400 WORDS)
J Mol Biol 1992 Sep 20
PMID:Alpha-helix stability in proteins. I. Empirical correlations concerning substitution of side-chains at the N and C-caps and the replacement of alanine by glycine or serine at solvent-exposed surfaces. 140 68

Putative genes for 21 ribosomal proteins (RPs) have been identified in the chloroplast DNA of four plants by nucleotide sequencing and homology comparison but few of the gene products have been characterized. Here we report the purification and N-terminal sequencing of seven proteins from the spinach chloroplast ribosome. The data show them to be the homologues of Escherichia coli RPs L20, L32, L33, L36, S12, S16 and S19, and thus support the view that their genes identified in the chloroplast DNA represent functional genes. The initiating methionine residue was not detected in the mature protein in most cases but it was present in S16, indicating that only the formyl group is removed in this case. This result and the previously reported finding of N-methyl alanine at the N-terminus of chloroplast L2 indicate the existence of multiple N-terminal processing pathways in the chloroplast.
Plant Mol Biol 1992 Nov
PMID:Purification and characterization of seven chloroplast ribosomal proteins: evidence that organelle ribosomal protein genes are functional and that NH2-terminal processing occurs via multiple pathways in chloroplasts. 142 Nov 49

We have used molecular dynamics simulations to determine the stability in water of a model beta-sheet formed by two alanine dipeptide molecules with two intermolecular hydrogen bonds in the closely spaced antiparallel arrangement. In this paper we describe our computations of the binding free energy of the model sheet and a portion of the free energy surface as a function of a reaction co-ordinate for sheet formation. We used the free energy surface to identify stable conformations along the reaction co-ordinate. To determine whether or not the model sheet with two hydrogen bonds is more stable than a single amide hydrogen bond in water, we compared the results of the present calculations to results from our earlier study of linear hydrogen bond formation between two formamide molecules (the formamide "dimer"). The free energy surfaces for the sheet and formamide dimer each have two minima corresponding to locally stable hydrogen-bonded and solvent-separated configurations. The binding free energies of the model sheet and the formamide dimer are -5.5 and -0.34 kcal/mol, respectively. Thus, the model sheet with two hydrogen bonds is quite stable while the simple amide hydrogen bond is only marginally stable. To understand the relative stabilities of the model sheet and formamide dimer in terms of solute-solute and solute-water interactions, we decomposed the free energy differences between hydrogen-bonded and solvent-separated conformations into energetic and entropic contributions. The changes in the peptide-peptide energy and the entropy are roughly twice as large for the sheet as they are for the formamide dimer. The magnitude of the peptide-water energy difference for the sheet is less than twice (by about 3.5 kcal/mol) that for the formamide dimer, and this accounts for the stability of the sheet. The presence of the side-chains and/or blocking groups apparently prevents the amide groups in the sheet from being solvated as favorably in the separated arrangement as in the formamide dimer, where the amide groups are completely exposed to the solvent.
J Mol Biol 1992 Oct 20
PMID:Stability of a model beta-sheet in water. 143 96

Nephrotoxic lesions were induced in Fischer 344 rats using HgCl2, a proximal tubular toxin, and 2-bromoethanamine (BEA), a medullary toxin. Biochemical effects of these toxins on urinary composition were observed by high resolution 1H NMR spectroscopy over 9 days after dosing. The onset of, progression of, and recovery from the induced toxic lesions were also followed histopathologically and related to the perturbed urinary biochemistry. Urinary concentrations of 20 endogenous substances were measured simultaneously by NMR at eight time points, to provide a time-related 20-dimensional description of the urinary biochemistry for each rat. Principal components analysis and nonlinear mapping were used to reduce the biochemical parameter spaces for each rat to two or three dimensions for display and classification purposes. An investigation of alternative data-presentation methods was made, and taking interanimal means of the map coordinates at each time point yielded a novel type of metabolic trajectory diagram with which the biochemical abnormalities associated with the HgCl2 and BEA lesions could be related to the progression and recovery phases of the toxic lesions. The time-course trajectories showed characteristically different paths for each toxin. These trajectories allowed the time points at which there were maximum metabolic differences to be determined and provided the visualization of net movements of the treatment group populations in time in relation to interanimal variation. Control animal urine samples subjected to this analysis showed simple clustering, with no evidence of metabolic trajectory. The trajectory for BEA showed different routes for onset of and recovery from toxicity, whereas for HgCl2 the outward trajectory (onset) mapped a space similar to the inward trajectory (recovery phase). This suggests that the NMR-detectable biochemical abnormalities after mercury toxicity mainly reflect the proportions of functional cells lining the nephron, whereas the biochemical abnormalities associated with renal medullary insult probably relate to functional integrity. An examination has been made for those metabolites that are most responsible for defining the trajectories, i.e., the discrimination of renal cortical and medullary toxicity from each other and from controls. These discriminatory metabolites (using paired t test, p < 0.001) included valine, taurine, trimethylamine N-oxide, and glucose for HgCl2 and acetate, methylamine, dimethylamine, lactate, and creatine for BEA, whereas citrate, succinate, N-acetyl resonances from as yet unidentified metabolites, hippurate, alanine, and 2-oxoglutarate played an important role in defining the biochemically perturbed trajectory of both toxins.(ABSTRACT TRUNCATED AT 400 WORDS)
Mol Pharmacol 1992 Nov
PMID:Nuclear magnetic resonance spectroscopy and pattern recognition analysis of the biochemical processes associated with the progression of and recovery from nephrotoxic lesions in the rat induced by mercury(II) chloride and 2-bromoethanamine. 143 56

We have generated 10 alanine mutants of human PRL (hPRL), a member of the PRL/GH family, to investigate the involvement of the highly conserved 58-74 region in the biological behavior of the protein. When treated with polyclonal anti-hPRL antibodies, all mutants were immunologically indistinguishable from the unmodified hPRL, and circular dichroism analyses indicated that their alpha-helix content was similar to that of the unmodified hormone. Mutations C58A, K69A, and, to a lesser extent, P66A affected drastically the ability of hPRL first to bind to the lactogenic receptor and second to stimulate the proliferation of Nb2 lymphoma cells, proving the importance of the 58-74 peptide segment for hPRL bioactivity. Binding affinities of these mutants to the Nb2 lactogenic receptor have been compared to lactogenic binding data previously obtained for several mutants of hGH. The comparison reveals that the residues involved in the biological properties of the two proteins are not at topologically equivalent positions. Hence, we suggest that the binding of these hormones to the lactogenic receptors occurs through a different molecular mechanism having distinct requirements at the residue level.
Mol Endocrinol 1992 Sep
PMID:Alanine-scanning mutagenesis of human prolactin: importance of the 58-74 region for bioactivity. 143 87


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