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)

The spatial structure of the methylamide of N-acetyl-L-lysine has been analysed taking into account non-bonded and electrostatic interactions, torsional energy, bond angles distortion and hydrogen bonding. Conformational capacities of the backbone and mutual dependence of spatial structures of the backbone and the side chain was described by conformational maps obtained by energy minimisation, the dihedral angles and the bond angles of the side chain being varied for every phi, psi point. Every possible combination for phi, psi, x1-x5-angles was used corresponding to the stable form of the backbone and to torsion potential minima of the initial approximations in the calculation of preferred conformations of the molecule. Comparisons are made between stable forms of the methylamide of N-acetyl-L-lysine and Lys residues in proteins with known structure.
Mol Biol (Mosk)
PMID:[Theoretical conformational analysis of methylamide of N-acetyl-L-lysine]. 121 93

Changes of quaternary structure and conformation of molecule concomitant with inactivation were observed in the course of aspartate transaminase acylation by maleic, citraconic, dimethylmaleic and succinic anhydrides. It was established that acylation of 10-12 xi-amino groups of lysine did not induce the dissociation of transaminase into subunits. Further acylation of amino groups (2 groups if dimethylmaleic anhydrade was used as acylating agent) induced dissociation of transaminase dimer into subunits. These data were obtained by sedimentation analysis. The dissociation was accompanied with a sharp decrease of correlation time (from 18 nsec to 9 nsec) of the paramagnetic label covalently bound to the protein. The obtained results allow us to distinguish three types of xi-aminogroups of aspartate transaminase: exposed (about 12 residues), "contact" (2 residues) located in the vicinity to complementary surfaces of subunits and buried (about 6 residues). The stepwise inactivation occurred during the acylation as a result of conformational changes or appearance of sterical hindrances in the cataytic site of the enzyme. The thiol groups were not modified in transaminase molecule under experimental conditions used. Aspartate transaminase treated with citraconic or dimethylmaleic anhydride may be deacylated under mild conditions. After reacylation the quaternary structure was reconstituted and catalytic activity was almost fully restored.
Mol Biol (Mosk)
PMID:[The effect of various acylating agents on the catalytic properties and structure of aspartate aminotransferase]. 121 97

Antisense oligonucleotides efficiently inhibit gene expression in vitro; however, the successful therapeutic application of this technology in vivo will require the development of improved delivery systems. In this report we describe a technique that efficiently delivers antisense oligonucleotides into cells using molecular conjugates. This technique, which was initially developed for the delivery of eukaryotic genes, is based on the construction of DNA-protein complexes that are recognized by the liver-specific asialoglycoprotein receptor. Binding of poly(L-lysine)-asialoorosomucoid (AsOR) protein conjugates with phosphorothioate antisense oligonucleotides to chloramphenicol acetyltransferase (CAT) led to the formation of 50- to 150-nm toroids. Exposure of the antisense molecular complexes (3 microM oligonucleotide) to NIH 3T3 cells genetically modified to express both the AsOR receptor and CAT, inhibited CAT expression by 54%, which was completely blocked by excess AsOR. Equivalent inhibition of CAT activity with purified oligonucleotide alone was observed at a 30 microM concentration. Furthermore, examination of the cells using indirect immunofluorescence for the presence of CAT protein showed 28% of cells exposed to the molecular conjugates lacked any detectable CAT enzyme. Cells exposed to oligonucleotide alone showed a highly variable staining pattern, and only a few of the cells were completely void of CAT protein. Together these data demonstrate that molecular conjugates provide a highly specific and efficient system for the delivery of antisense oligonucleotides.
Somat Cell Mol Genet 1992 Nov
PMID:Targeted delivery of antisense oligonucleotides by molecular conjugates. 128 54

To define the heparin-binding site of follistatin, the reduced and S-carboxymethylated recombinant human follistatin containing 288 amino acids was digested by Staphylococcus aureus V8. The digested product was subjected to sulfate cellufine column chromatography and the adsorbed peptide fragments eluted with a stepwise gradient of sodium chloride. The recovered column fractions were further purified by reversed-phase high-performance liquid chromatography (HPLC) and the HPLC peaks subjected to amino-terminal sequence analysis. All of the sulfate cellufine-retarded peptide fragments gave the same N-terminal amino acid sequence, which started at residue-68 of human follistatin, suggested that those fragments starting from residue-68 contain the heparin binding site. The multiple fragments might represent the oxidized, non-glycosylated or glycosylated forms of follistatin(68-113) resulting from the V8 digestion. A synthetic peptide corresponding to the region having the amino acid sequence 72-86 of follistatin was able to bind both heparin and sulfate cellufine, as well as compete with recombinant follistatin for binding to heparin. These findings further define the location of the heparin and heparan sulfate-binding site of follistatin at the basic amino acid-rich region comprising the amino acid sequence Lys75-Lys-Cys-Arg-Met-Asn-Lys-Lys-Asn-Lys-Pro-Arg86.
Mol Cell Endocrinol 1992 Dec
PMID:Localization of the heparin binding site of follistatin. 130 90

Previous calculations of electrostatic interactions in the rhinovirus capsid have identified a subset of histidine residues, paired with lysine or arginine, that may be involved in pH-induced conformational changes related to viral uncoating. Further calculations with the finite difference method, accounting for the dielectric environment of the ionizable groups, suggest that charge burial in the crystal conformation will prevent protonation of these histidine residues in the pentamer-pentamer interface. Calculations with a modelled pentamer-pentamer interface in which three beta-strands are removed recover mildly acidic pKa values for the histidines. These results are discussed in the context of the structural interactions of these three beta-strands, which form a beta-sheet extension from the rest of the capsid, and with regard to the conformation of the homologous beta-sheet extension in poliovirus, which also possesses homologous histidine-lysine/arginine pairs. A model is developed in which the structural stability of the beta-sheet extension is related to the difference in acid stability of rhinovirus and poliovirus. It is suggested that, for poliovirus prior to cell receptor binding, the beta-sheet extension is stable at pH 3, the pentamer-pentamer interface histidines remain buried, and the virus is acid-stable. Cell receptor binding of poliovirus destabilizes the beta-sheet extension and the acid lability that is proposed to result could be involved in viral uncoating. For rhinovirus it is suggested that the observed conformational change in the absence of cell receptor binding involves a further acidic pH-activated process or conformational fluctuations that rearrange the beta-sheet extension and expose the pentamer-pentamer interface histidine residues to the acidic medium. Sequence analysis and electrostatics calculations reveal an aspartic acid in the beta-sheet extension that may have different pKa values in rhinovirus and poliovirus.
J Mol Biol 1992 Jan 05
PMID:Model for the differential stabilities of rhinovirus and poliovirus to mild acidic pH, based on electrostatics calculations. 130 85

Cloning and sequencing of cDNA segments of human TOP2 gene encoding the 170 kDa form of human DNA topoisomerase II show that Arg486 of the enzyme has been mutated to a lysine in the enzyme from two human leukemia cell lines HL-60/AMSA and KBM-3/AMSA, which were independently selected for resistance to the antitumor drug amsacrine (4'-[9-acridinylamino]-methanesulfon-m-anisidide, mAMSA). Sequence identity comparisons between eukaryotic DNA topoisomerase II and bacterial gyrase (bacterial DNA topoisomerase II) indicate that the position of the common mutation observed in mAMSA-resistant human TOP2 corresponds to that of the point mutation nal-31 in the Escherichia coli gyrase B gene, which confers resistance to nalidixic acid. Because mAMSA and nalidixic acid are known to act on their respective targets by a common mechanism of trapping the covalent enzyme-DNA intermediates, these results provide strong evidence that the 170 kDa form of human DNA topoisomerase II is a major cellular target of mAMSA, and that Arg486 of this enzyme is involved in mAMSA-mediated trapping of the covalent enzyme-DNA complex.
J Mol Biol 1992 Feb 20
PMID:Two independent amsacrine-resistant human myeloid leukemia cell lines share an identical point mutation in the 170 kDa form of human topoisomerase II. 131 90

Thirteen 4,5-epoxymorphinan mu agonists with established analgesic action were docked into an Asp-Lys-His-Phe pseudoreceptor complex under a range of distance-dependent dielectric conditions. The number of compounds with potential energies of the docked complexes that agreed in rank order with corresponding analgesic potencies was determined for each condition. Two dielectric conditions, n-decane (1.991) and ethanol (24.3), enabled the greatest number of compounds to relate to their pseudoreceptors with each having 9 and 8 successes respectively. Both of these conditions demonstrated unique influences on the types of structures that were successfully docked. For example, the morphine stereoisomer alpha-isomorphine, the geometric isomer B/C trans-morphine, and the 8-position-substituted gamma-isomorphine were successes in the n-decane condition, whereas the ethanol condition produced the substituted codeine derivatives dihydrocodeinone and dihydroxycodeinone. These findings emphasize the importance of dielectric influence when developing force-field modeled quantitative structure-activity relationships for a closely related homologous series.
J Comput Aided Mol Des 1992 Apr
PMID:A pseudoreceptor docking study of 4,5-alpha-epoxymorphinans with a range of dielectric constants. 132 Jun 64

A complementary DNA (cDNA) for mouse hypothalamic preprothyrotropin-releasing hormone (TRH) was isolated and characterized using three different combinations of the polymerase chain reaction (PCR). Using this cDNA, we examined the tissue distribution of expression of the mouse preproTRH gene and evaluated the evolutionary basis of the preproTRH gene by comparison of the cloned sequence with sequences of preproTRH in other species. The deduced protein sequence of the mouse preproTRH contained 256 amino acids featured by possessing an insertion of one amino acid as compared with that of rat preproTRH. Five repetitive copies of the TRH progenitor sequence (Lys-Arg-Gln-His-Pro-Gly-Arg/Lys-Arg) were found in the mouse preproTRH. Northern blot analysis showed an apparent single band of hypothalamic mRNA of approximately 1600 base pairs in length. The homology of the coding region of the mouse preproTRH with the rat and human preproTRH is 92 and 65% at the nucleic acid level, respectively, and 88 and 56% at the amino acid level, respectively. By means of the PCR procedure, a characteristic expression of the preproTRH mRNA was observed solely in the mouse hypothalamus and testis. Moreover, it was noteworthy to find that the degree of homology to the region containing the sixth TRH-coding sequence of the human preproTRH was higher in the mouse preproTRH than the rat counterpart.(ABSTRACT TRUNCATED AT 250 WORDS)
Brain Res Mol Brain Res 1992 Jun
PMID:Cloning of the mouse hypothalamic preprothyrotropin-releasing hormone (TRH) cDNA and tissue distribution of its mRNA. 132 11

The molecular conformation of ubiquitinated structures and the validity of the N-end rule were examined by simulating the molecular mechanics to ascertain the global energy-minimized structure. We examined the chemical linkage involved in attaching the ubiquitin carboxyl terminus to the N-terminus of three different x-hexapeptides, where x is the amino group of the acceptor peptide--either valine, arginine or glutamic acid--(x-K linkage) and to the epsilon-amino group of lysine of the acceptor hexapeptide x-glu1-his2-lys3-gly4-lys5-val6 (K-K linkage) through the formation of an isopeptide bond. Changes in conformation and molecular stability of the multi-ubiquitinated structures were determined by energy-minimization procedures using the SYBYL program developed by Tripos Associates. In the x-K linkage, the ubiquitin molecule is stretched in the beta-pleated sheets and beta-turns while the alpha-helices expand, as the molecule continues to unfold linearly. In the K-K linkage, the ubiquitin molecules have turned into a u-shaped, semi-circular alignment, contracting into a compact, folded structure.
J Mol Graph 1992 Mar
PMID:Molecular conformation of ubiquitinated structures and the implications for regulatory function. 132 99

We have used a guinea pig gastric longitudinal (LM) smooth muscle bioassay system to evaluate the contractile activities of a previously described thrombin receptor-derived polypeptide, S42FLLRNPNDKYEPF55 (one-letter amino acid code) (TRP42-55) and of a series of peptides derived from this sequence. The contractile activities of the polypeptides were compared with the actions of thrombin. Shortened peptides of the sequences S42FLLRNPND50, S42FLLRN47, and S42FLLR46 (TRP42-46) all exhibited contractile activities that were equivalent to or greater than those of the parent polypeptide, TRP42-55. Both TRP42-55 and TRP42-46 mimicked the action of thrombin, in terms of two different signal transduction pathways that were activated either in the LM preparation or in the related but distinct gastric circular muscle assay. In the LM preparation, the peptide FSLLR also exhibited appreciable, but much reduced, activity. Minimal activity was exhibited in the LM by the sequence SFLLA, but the lysine-containing analogue S42FLLK46 was about one fifth as potent as TRP42-46. In contrast, the receptor-derived sequences S42FLL45, S42FL44-NH2, F43LLR46, and S42ALLR46, as well as arginine-containing polypeptides beginning with the SF motif, SFRG and SFRGHITR, were inactive in the LM bioassay system, at concentrations of greater than or equal to 200 microM, as either agonists or antagonists against TRP42-55. In addition to its actions in the LM and circular muscle preparations, the active pentapeptide, TRP42-46, also exhibited thrombin-mimetic intrinsic activity in a rat aortic arterial ring relaxation bioassay, whereas the pentapeptide S42FLLA46 and the tetrapeptide S42FLL45 were inactive. We conclude that the intrinsic biological activity of the thrombin receptor-derived peptide resides in the pentapeptide TRP42-46 and that the phenylalanine and arginine residues at positions 43 and 46 play key roles in the activity of this pentapeptide in smooth muscle systems.
Mol Pharmacol 1992 Aug
PMID:Action of thrombin receptor polypeptide in gastric smooth muscle: identification of a core pentapeptide retaining full thrombin-mimetic intrinsic activity. 132 29


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