Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “TERT”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1988

[3H][D-Ser2(O-tert-butyl),Leu5]enkephalyl-Thr6 and [D-Ser2(O-tert-butyl),Leu5]enkephalyl-Thr6(O-tert-butyl). Two new enkephalin analogs with both a good selectivity and a high affinity toward delta-opioid binding sites.

Insertion of bulky tertiobutyl groups into the sequence of [D-Ser2,Leu5]enkephalyl-Thr6 leads to a conformationally induced large increase in selectivity toward rat brain delta-opioid binding sites, as shown by the ratio of apparent affinities for mu and delta receptors of [D-Ser2(O-tert-butyl),Leu5]enkephalyl-Thr6,KI(mu)/KI(delta) = 130, and [D-Ser2(O-tert-butyl),Leu5]enkephalyl-Thr6 (O-tert-butyl),KI(mu)/KI(delta) = 280. In addition to a selectivity similar to that of the cyclic compounds [D-Pen2, D-Pen5]enkephalin and [D-Pen2,L-Pen5]enkephalin, the affinity of [3H][D-Ser2(O-tert-butyl),Leu5]enkephalyl-Thr6 for the delta sites of rat brain membranes is significantly better (KD = 2.2 nM) than that of [3H][D-Pen2,D-Pen5]enkephalin (KD approximately 8.5 nM). Therefore, [3H][D-Ser2(O-tert-butyl),Leu5]enkephalyl-Thr6 seems to be the most appropriate delta-probe currently available for binding studies. Moreover, the lipophilic and protected peptide [D-Ser2(O-tert-butyl),Leu5]enkephalyl-Thr6(O-tert-butyl) behaves as the most specific ligand for the delta-opioid binding sites and appears appropriate for in vivo investigations. The inactive analogue [D-Thr2(O-tert-butyl),Leu5]enkephalyl-Thr6 might serve as a negative control in biochemical or pharmacological studies.

Animals↗
PubMed1986

Histologic and autoradiographic studies on the forestomach of hamsters treated with 2-tert-butylated hydroxyanisole, 3-tert-butylated hydroxyanisole, crude butylated hydroxyanisole, or butylated hydroxytoluene.

The inductions of hyperplasia and neoplastic lesions in the forestomach of Syrian golden hamsters by 2-tert-butylated hydroxyanisole [(2-tert-BHA) CAS: 121-00-6], 3-tert-butylated hydroxyanisole [(3-tert-BHA) CAS: 88-32-4], crude butylated hydroxyanisole [(BHA) CAS: 25013-16-5], and butylated hydroxytoluene [(BHT) CAS: 128-37-0] were compared histopathologically and autoradiographically. In hamsters fed the 2-tert-BHA diet, severe hyperplasia developed from week 4, reaching a maximum level in week 16 of 0.56 cm/10 cm basement membrane (bm), and papillomatous lesions appeared in week 16 (0.13 cm/10 cm bm). In hamsters fed 3-tert-BHA or crude BHA, severe hyperplasia developed from week 1, which reached a maximum level in week 4 of 3.63 cm/10 cm bm with 3-tert-BHA and 5.10 cm/10 with crude BHA; it then decreased. Papillomatous lesions were found in week 3 in hamsters fed 3-tert-BHA and in week 4 in hamsters fed crude BHA; they increased to maximum levels in week 16 of 0.50 cm/10 cm bm with 3-tert-BHA and 0.29 cm/10 cm bm with crude BHA. Mild hyperplasia occurred slightly more often in hamsters fed the BHT diet than in the control group. BHT induced no severe hyperplasia and papillomatous lesions. Changes in the labeling index of the forestomach epithelium paralleled the histologic changes, except in hamsters fed the BHT diet in which no significant increase in the labeling index was observed throughout the experiment. These data suggest that the tumorigenic action of crude BHA on hamster forestomach is largely due to 3-tert-BHA and that BHT does not induce forestomach tumors in hamsters.

Animals↗
PubMed1992

Formation of the semiquinone anion radical from tert-butylquinone and from tert-butylhydroquinone in rat liver microsomes.

The tert-butylsemiquinone anion radical is formed from tert-butylhydroquinone and from tert-butylquinone in rat liver microsomes. In the presence of oxygen, the quinone and, less extensively, the hydroquinone induce excess production of superoxide in microsomes. It is concluded that autoxidation of the semiquinone formed from the quinone by microsomal enzyme activity is responsible for superoxide formation and that the hydroquinone enters the redox cycle via autoxidation. tert-Butylquinone induces injury of the hepatocyte plasma membrane. tert-Butylhydroquinone and tert-butylquinone are metabolites of the antioxidant butylated hydroxyanisole. The semiquinone-dependent superoxide formation may contribute to the toxic actions of butylated hydroxyanisole.

Animals↗
PubMed1985

Metabolism of 3-tert-butyl-4-hydroxyanisole to 3-tert-butyl-4,5-dihydroxyanisole by rat liver microsomes.

3-tert-Butylhydroxyanisole (3-BHA) is an antioxidant which can have a modulating effect on chemical carcinogenesis. Information concerning the metabolism of 3-BHA is incomplete. In the present study, the metabolites formed by incubating 3-BHA with liver microsomes from rats given beta-naphthoflavone by p.o. intubation were studied. Three metabolites were identified, two major metabolites and a minor metabolite. One of the major metabolites was the catechol of 3-BHA, i.e., 3-tert-butyl-4,5-dihydroxyanisole, which has not previously been reported. A characteristic of this compound is its capacity to be oxidized readily. The second major metabolite was tert-butyl hydroquinone which has been reported previously to be a liver microsomal metabolite of 3-BHA. The third metabolite, which occurred in small quantities, was 2,2'-dihydroxy-3,3'-di-tert-butyl-5,5'-dimethoxydiphenyl. 2,2'-Dihydroxy-3,3'-di-tert-butyl-5,5'-dimethoxydiphenyl has been identified previously as a major metabolite of 3-BHA in the rat intestine. An understanding of the metabolism of 3-BHA may assist in elucidating the mechanism(s) of its biological effects.

Animals↗
PubMed1978

[Direct tert-butylation of tryptophan: preparation of 2,5,7-tri-tert-butyltryptophan (author's transl)].

The tert-butylation of free tryptophan under simulated conditions of acidolytic cleavage of protecting groups being based on a tert-butyl moiety does finally yield the tri-substituted amino acid as a main product, namely 2,5,7-tri-tert-butyltryptophan. The structural elucidation of this substance and other tert-butylated products, which were isolated mostly in a pure form, was achieved by means of spectroscopic methods, in particular mass spectrometry and nuclear magnetic resonance spectroscopy.

Chemical Phenomena↗
PubMed1978

[tert-Butylation of the tryptophan indole ring during the removal of the tert-butyloxycarbonyl group (author's transl)].

The tert-butylation of the tryptophan indole ring during the removal of tert-butyloxycarbonyl groups under different conditions was studied. The incorporation of tert-butyl groups was measured by a 1H-NMR technique. It was established, that the rate and specificity of the tert-butylation is highly dependent on the character of the cleaving reagents used and on the environment of the tryptophan residue in the peptide chain.

Chemical Phenomena↗
PubMed1988

Effects of p-tert-butylphenyl trans-4-guanidinomethylcyclohexane carboxylate hydrochloride (NCO-650) and its metabolite, p-tert-butylphenol(BP) on drug-metabolizing enzymes and fine structure in rat liver.

The effects of p-tert-butylphenyl trans-4-guanidinomethylcyclohexane carboxylate hydrochloride (NCO-650) and its metabolite, p-tert-butylphenol(BP), on the drug-metabolizing enzymes and fine structure in the rat liver were examined. Aminopyrine demethylase activity was inhibited by the administration of NCO-650 and BP at a dose of 2 and 10 mg/kg, p.o. The increases of microsomal cytochrome b5 and cytochrome P-450 contents were noticed at 1, 12 and 24 hr after NCO-650 and BP administration. Ascorbate-dependent lipid peroxidation of mitochondria and microsome increased by the administration of NCO-650 and BP, but NADPH-dependent lipid peroxidation decreased by these drugs. In the morphological observations of fine structure in the liver, NCO-650 and BP caused the swelling and decrease of rough endoplasmic reticulum and the increase of smooth endoplasmic reticulum. The morphological changes of liver fine structure were related to the changes of drug-metabolizing enzymes in the liver by the administration of NCO-650 and BP, which may be suggest the transitory and functional responses of these drugs in the liver. The effect of BP on the drug-metabolizing enzymes and fine structure in the liver was similar to that of NCO-650.

Aminopyrine N-Demethylase↗
PubMed1991

Systemic administration of (Tyr-D-Ser(O-tert-butyl)-Gly-Phe-Leu-Thr(O-tert-butyl), a highly selective delta opioid agonist, induces mu receptor-mediated analgesia in mice.

The mu opioid receptors are unquestionably implicated both in supraspinal and spinal analgesia, but there is some controversy about the role of delta receptors in the control of pain at the supraspinal level. This could be due, at least in part, to the local or i.c.v. administration of the opioid agonists. It was therefore interesting to reassess the overall contribution of mu and delta opioid receptors in modulating nociceptive thermal stimuli in the hot plate-test in mice after i.v. injections of DAMGO (Tyr-D-Ala-Gly-(NMe)Phe-Gly-ol) and BUBU (Tyr-D-Ser(O-tert-butyl)-Gly-Phe-Leu-Thr(O-tert-butyl), two highly selective mu and delta receptor agonists, respectively, whose passage into the brain has been demonstrated recently. Both agonists induced dose-dependent, short-lasting (less than 30 min), antinociceptive responses that peaked 5 min after the administration of DAMGO and 10 min after the administration of BUBU. At these times, DAMGO [ED50: 1.26 mumols (0.65 mg)/kg] was 34 times more potent than BUBU [ED50: 42.5 mumols (34 mg)/kg] in the jump response and 13 times more potent in the paw lick. Apparent pA2 values of naloxone (0.004-0.1 mg/kg s.c.) antagonism for DAMGO and BUBU did not differ significantly, 6.95 +/- 0.054 and 7.28 +/- 0.030 for paw lick tests and 7.11 +/- 0.045 and 7.25 +/- 0.027 for jump tests, respectively. The slopes of the pA2 plots were close to the theoretical -1 value for competitive antagonism.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗
PubMed1989

Synthesis of thyrotropin-releasing hormone-related peptides using N alpha-tert-butyloxycarbonyl-omega-(N-tert-butyloxycarbonylcarbamoyl)- alpha-amino acids.

Application of N alpha,Nca-di-tert-butyloxycarbonylhomoglutamine to synthesis of thyrotropin-releasing hormone (TRH) analogs was examined. The delta-lactam formation from homoglutaminylpeptides took place more easily than gamma-lactam formation from glutaminylpeptides in water or dioxane containing acetic acid. [pHgu1,Nva2]-TRH had dose-dependent antagonistic activity against pentobarbital anesthesia in mice, but almost no binding activity to TRH receptor in rat brain.

Amino Acids↗
PubMed1988

Crystal and molecular structure of the antimalarial agent 4-(tert-butyl)-2-(tert-butylaminomethyl)-6-(4-chlorophenyl)phenol dihydrogen phosphate (WR 194,965 phosphate).

WR 194,965 phosphate, a new antimalarial agent containing a biphenyl ring structure active against chloroquine-resistant Plasmodium falciparum, crystallized in ionic form with a positive charge on the quaternary nitrogen atom. The oxygen and nitrogen atoms of WR 194,965 were hydrogen bonded to the same phosphate group. The nitrogen atom was also hydrogen bonded to a second phosphate group. The phosphate ions formed discrete clusters of four phosphate moieties. The phosphate clusters contained fourfold inversion symmetry. The intramolecular N-O distance in WR 194,965 of 3.073 A (1 A = 0.1 nm) was close to the reported values for N-O distances in the active cinchona alkaloids and may be important for activity. A comparison of the crystalline structure of WR 194,965 with those of mefloquine and quinidine sulfate demonstrated that the regions of the three molecules in the vicinity of the aliphatic nitrogen atom and the oxygen atom superimpose. Much of the remainder of the WR 194,965 molecule spatially overlapped with the combined three-dimensional space defined by quinidine and mefloquine. The crystallographic parameters were: C21H29ClNO+.H2PO4-; Mr = 443.9; symmetry of unit cell, tetragonal; space group, I41/a; parameters of unit cell, a = b = 24.305 +/- 0.002 A, c = 17.556 +/- 0.003 A; V (volume of unit cell) = 10370.9 A3; Z (number of molecules per unit cell) = 16; Dx (calculated density) = 1.137 g cm-3; source of radiation, CuK alpha (lambda = 1.54178 A); mu (absorption coefficient) = 21.3 cm-1; F(000) (sum of atomic scattering factors at zero scattering angle) = 3,440; room temperature; final R = 8.2% for 2,508 reflections with [F0] greater than 3 sigma.

Animals↗
PubMed1988

Proline-containing beta-turns. IV. Crystal and solution conformations of tert.-butyloxycarbonyl-L-prolyl-D-alanine and tert.-butyloxycarbonyl-L-prolyl-D-alanyl-L-alanine.

The conformations of the dipeptide t-Boc-Pro-DAla-OH and the tripeptide t-Boc-Pro-DAla-Ala-OH have been determined in the crystalline state by X-ray diffraction and in solution by CD, n.m.r. and i.r. techniques. The unit cell of the dipeptide crystal contains two independent molecules connected by intermolecular hydrogen bonds. The urethane-proline peptide bond is in the cis orientation in both the molecular forms while the peptide bond between Pro and DAla is in the trans orientation. The single dipeptide molecule exhibits a "bent" structure which approximates to a partial beta-turn. The tripeptide adopts the 4----1 hydrogen-bonded type II beta-turn with all trans peptide bonds. In solution, the CD and i.r. data on the dipeptide indicate an ordered conformation with an intramolecular hydrogen bond. N.m.r. data indicate a significant proportion of the conformer with a trans orientation at the urethane-proline peptide bond. The temperature coefficient of the amide proton of this conformer in DMSO-d6 points to a 3----1 intramolecular hydrogen bond. Taken together, the data on the dipeptide in solution indicate the presence (in addition to the cis conformer) of a C7 conformation which is absent in the crystalline state. The spectral data on the tripeptide indicate the presence of the type II beta-turn in solution in addition to the nonhydrogen-bonded conformer with the cis peptide bond between the urethane and proline residues. The relevance of these data to studies on the substrate specificity of collagen prolylhydroxylase is pointed out.

Circular Dichroism↗