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J Meienhofer

Publications and source records attributed to J Meienhofer.

At least 19 recordsLinked to original sources
PubMed1986

Synthesis of a potent enkephalin analog, Tyr-D-Thr-Gly-Phe-delta 3 Pro-NH2, and some of its biological activities.

The enkephalin analog, H-Tyr-D-Thr-Gly-Phe-delta 3 Pro-NH2 X HCl (VI) ([D-Thr2, delta 3 Pro5]-enkephalinamide), has been synthesized by conventional methods in solution and purified to homogeneity by reversed phase HPLC. The analog is a potent analgesic agent. For evaluation of some of its biological activity a related compound [D-Thr2, Thz5]-enkephalinamide (XI) was also synthesized in solution. Anti-diarrhea activity was evaluated in mice by the intravenous route for anti-DL-5-hydroxytryptophan (5-HTP) induced diarrhea activity. Analgesic activity was assayed by the method of Nilsen in mice using the intravenous route, and by a modified tail flick test in rats and the acetic acid writhing test in mice following subcutaneous administration. Within the constraints of the assays the two analogs are approximately equipotent. Both are less active than [D-Ala2, MePhe4, Met(0)ol]-enkephalinol (XII). Earlier receptor binding studies of compound XI indicated enhanced affinity for the mu receptor and little for the delta receptor. By comparison this may also be the case for compound VI.

Analgesics↗
PubMed1984

A revised primary structure for neocarzinostatin based on fast atom bombardment and gas chromatographic-mass spectrometry.

The amino acid sequence of the antitumor protein neocarzinostatin was revised on the basis of mass spectrometric studies. Gas chromatographic mass spectrometry on the O-trimethylsilyl polyaminoalcohol derivatives of peptide mixtures derived from tetra S-carboxymethyl-neocarzinostatin were used to partially sequence neocarzinostatin. In addition, fast atom bombardment-mass spectrometric experiments on neocarzinostatin and its tryptic fragments gave the molecular weights of various peptides and, in some cases, partial sequence information. The revised sequence involved reordering of two chymotryptic peptides, the identification of a new di- and tripeptide sequence (Ala-Asp and Ala-Ser-Thr), the repositioning of Trp at position 39, and the assignment of the remaining Asx residues. The revised structure for neocarzinostatin (Mr = 11,105) now shows considerable homology with the other antitumor antibiotic proteins macromomycin and actinoxanthin.

Amino Acid Sequence↗
PubMed1984

Synthesis of analogs and oligomers of N-(2-aminoethyl)glycine and their gastrointestinal absorption in the rat.

The synthesis of a series of analogs and oligomers of N-(2-aminoethyl)glycine (Aeg) are described. The gastrointestinal absorption of these compounds was determined after intragastric administration. Analogs of Aeg bearing a substituent at the amino or carboxyl functions were absorbed to a lesser extent than the parent compound. In contrast, the di- and tetra-oligomers of Aeg were more rapidly absorbed. Total absorption of these compounds was observed within 2 h after intragastric administration.

Animals↗
PubMed1984

The in vivo gastrointestinal absorption in rats of the intact cyclo(L-leucylglycine) dipeptide.

Unanesthetized rats with catheterized portal veins were administered, intragastrically, a saline solution of the diketopiperazine cyclo(L-leucyl-[U-14C]glycine) (cyclo(L-Leu-[14C]Gly)) at a dose of 47.9 nmol. The appearance of this cyclic dipeptide in portal vein plasma was followed chromatographically using a microcolumn of Sephadex G-25 complexed with copper. Further identification was done by thin-layer chromatography. Net absorption was evaluated by the balance method. The intestinal site of maximal absorptive capacity for cyclo(L-Leu-[14C]Gly) was also investigated. The gastric emptying rate was 98% in 15 min. After intragastric administration, cyclo(L-Leu-[14C]Gly) was absorbed (peak at 2.5 min) into the portal vein. The balance method showed that the efficiency of absorption was 94% within the first 10 min and was completed after 20 min. This compound was absorbed intact and remained unmetabolized in the portal vein of the rat and seemed to be absorbed throughout the length of the small intestine. Shortly after administration (1- to 5-min period), the greatest absorption of the diketopiperazine occurred at the level of the duodenum; however, the absorption maximum appeared to move down the gut and after 10 min the highest uptake took place in the jejunum, but never seemed to reach the ileum to a significant degree. Only negligible amounts of the cyclic dipeptide were excreted with the feces. Cyclo(L-Leu-[14C]Gly) is thus an example of a low molecular weight peptide which is rapidly and completely absorbed, after its intragastric administration at low concentration and is enzymatically stable during the process of absorption. In vitro experiments determined that this peptide apparently traverses the intestinal wall passively and does not use the carrier-mediated mechanisms for linear peptides.

Animals↗
PubMed1983

Peptide E: opiate receptor binding profile in the rat brain membrane assay. Comparison with beta-endorphin.

Beta-endorphin (beta-EP) and peptide E were compared in respect to their binding potency in the rat brain membrane by radioreceptor binding assay using tritiated human beta-EP, [D-Ala2,D-Leu5]-enkephalin (DADLE), dihydromorphine (DHM) and ethylketocyclazocine (EKC) as primary ligands. When the potency of beta h-EP was chosen to be 100%, peptide E was equipotent with beta-EP in displacing DHM (95%) and EKC (103%) less potent for competing with beta h-EP (60%) and least active (7%) for displacing DADLE. It may be concluded that peptide E binds preferentially with the opiate mu and kappa receptors in the rat brain membrane.

Animals↗
PubMed1983

Synthesis of adrenal peptide E and some of its biological activities.

A synthesis of peptide E, a highly potent, 25-amino acid adrenal opioid peptide containing both a [Met]enkephalin at the NH2-terminus and [Leu]enkephalin sequence at the COOH-terminus, originally isolated from bovine adrenal medulla [D. L. Kilpatrick, T. Taniguchi, B. N. Jones, A. S. Stern, J. E. Shively, J. Hullihan, S. Kimura, S. Stein, and S. Udenfriend (1981) Proc. Natl. Acad. Sci. USA 78, 3265-3268], is reported. The synthesis was accomplished by the solid-phase method employing the 4-(aminoacyloxymethyl)phenylacetamidomethyl(Pam)-copoly(styrene-1% divinylbenzene) resin. Two synthetic strategies (N-indole formyl protected vs unprotected tryptophan) were followed and results compared and evaluated. It was determined that peptide E prepared with protection of tryptophan (residues 13 and 14) was preferred and gave final product that was readily purified by HPLC. The biological activity of the synthetic material was found to be equivalent to the reported activity of the natural compound.

Amino Acid Sequence↗
PubMed1983

Confirmation of the primary structure of thymosin alpha1 by microsequence analysis of limited acid and enzymatic hydrolysis fragments.

The primary structure of the 28-peptide thymosin alpha 1 as determined by Goldstein et al. (1) has been confirmed by independent procedures. Limited dilute acid digestion generated a 26-peptide and a 22-peptide both extending to the C-terminal and lacking the N-terminal blocking group. A combination of Edman microsequencing, carboxypeptidase Y and thermolysin digestion, and fast atom bombardment mass spectrometry was used.

Amino Acid Sequence↗
PubMed1981

Stable isolated symmetrical anhydrides of N alpha-9-fluorenylmethyloxycarbonylamino acids in solid-phase peptide synthesis. Methionine-enkephalin synthesis as an example.

The synthesis and isolation of symmetrical anhydrides of N alpha-9-fluorenylmethyloxycarbonyl (Fmoc) amino acids using water soluble carbodiimide is described. These compounds were used in a solid phase peptide synthesis of methionine-enkephalin on a p-benzyloxybenzyl ester polystyrene 1% divinylbenzene resin support. Homogeneous free pentapeptide was obtained in 42% overall yield. The Fmoc amino acid symmetrical anhydrides were stable during prolonged storage (2 years of 0 degrees) and offer advantages over present "Fmoc solid phase" methods which use anhydrides formed in situ.

Amino Acids↗
PubMed1980

Preparation and properties of Nalpha-9-fluorenylmethyloxycarbonylamino acids bearing tert.-butyl side chain protection.

The preparation is described by several Nalpha-9-fluorenylmethyloxycarbonylamino acids and derivatives bearing tert.-butyl type side-chain protection of amine, carboxyl, guanido, hydroxyl, imidazol, and sulfhydryl functionalities. Physicochemical properties of these compounds have been determined. Cleavage of the Fmoc group by various amines appears to depend on the base strength and steric hindrance. Premature deblocking of Fmoc group by amine on solid support is very slow and may be negligible under the conditions of solid-phase synthesis.

Amino Acids↗
PubMed1980

Synthesis of somatostatin and [D-Trp8]-somatostatin.

Experimental details for practical syntheses of somatostatin and D-Trp8-somatostatin are described. The peptides were assembled from three fragments which permit further syntheses of analogs with modifications at positions 1, 2 or 8. N alpha-Bpoc protecting groups were used for the two major fragments and these were selectively removed in the presence of the tert.-butyl derived amino acid side chain functionalities. The two cysteine residues were protected by acetamidomethyl groups. All the peptide intermediates were fully characterized and a 10-g synthesis of the protected tetradecapeptide is reported. Major fragments were coupled by the azide method in good yield. Dihydrosomatostatin and D-Trp8-dihydrosomatostatin were isolated, purified, characterized and cyclized. Polymeric side-product was successfully recycled (by reduction with dithiothreitol and reoxidation) to give an overall yield for the oxidation of 52%. Somatostatin and D-Trp8-somatostatin were purified by gel filtration or countercurrent distribution and the final products were fully characterized and determined to be > 97% pure by reversed phase high performance liquid chromatography.

Amino Acid Sequence↗
PubMed1980

Synthesis of human beta-endorphin in solution using benzyl-type side chain protective groups.

A solution synthesis of human beta-endorphin (beta-EP) was carried out by condensation of protected peptide segments bearing N alpha-tert.-butyloxycarbonyl groups and benzyl-derived groups for the protection of functionalities in amino acid side chains. Five intermediate segments were assembled in a stepwise manner starting at the carboxyl terminus. Thus, the segment of sequence region (27-31) was coupled to segment (22-26) by the azide method. Segment (19-21) was incorporated into the growing chain by azide coupling, and segment (10-18) by dicyclohexylcarbodiimide coupling in the presence of 1-hydroxybenzotriazole (DDC-HOBt). Solubility problems in condensing the ensuing 22-peptide with segment (1-9) by DDC-HOBt were overcome by using a dimethylformamidephenol mixture as a solvent. Protecting group cleavage by Na in liquid NH3 was much superior to liquid HF which gave rise to many decomposition products. Homogeneous betah-EP indistinguishable from authentic material in physiochemical and biological properties, was obtained in a single preparative reversed phase liquid chromatographic step after protecting group cleavage.

Amino Acid Sequence↗
PubMed1980

Solid-phase peptide synthesis of somatostatin using mild base cleavage of N alpha-9-fluorenylmethyloxycarbonylamino acids.

Experimental details for the "Fmoc solid phase peptide synthesis" of somatostatin are described. The 9-fluorenylmethyloxycarbonyl group was rapidly and quantitatively cleaved by 55% piperidine in dimethylformamide and monitored (u.v.) manually. For a kinetic study, a centrifugal reactor with a photometric control system and reference cell was used at each stage. The symmetrical anhydride coupling reaction was rapid and either acetic anhydride or fluorescamine termination was incorporated to minimize formation of deletion peptides. Anchor-bond cleavage was effected with trifluoroacetic acid which simultaneously removed all the acid labile tert.-butyl side chain protecting groups. N alpha-9-fluorenylmethyloxycarbonyl peptides may be obtained by omitting the piperidine deprotection step after the last cycle of synthesis. From several syntheses, analytically pure di-S-protected somatostatin 14-peptide was obtained in 55-60% overall yield. The S-protecting groups were removed and the product was purified by gel filtration to give homogeneous dihydrosomatostatin (91%) yield. Oxidation of dihydrosomatostatin with potassium ferricyanide and purification by countercurrent distribution provided analytically pure homogeneous somatostatin.

Amino Acid Sequence↗
PubMed1979

Solid phase synthesis without repetitive acidolysis. Preparation of leucyl-alanyl-glycyl-valine using 9-fluorenylmethyloxycarbonylamino acids.

The utility of repetitive nonhydrolytic base cleavage of alpha-amino protective groups in solid phase peptide synthesis is shown by a preparation of the model tetrapeptide leucyl-alanyl-glycyl-valine on a p-benzyloxybenzyl ester polystyrene--1% divinylbenzene resin support. Nalpha-9-Fluorenylmethyloxycarbonyl (Fmoc: Carpino & Han, 1970, 1972) amino acids were coupled by the symmetrical anhydride procedure, followed by Fmoc group cleavage using 50% piperidine in methylene chloride. Quantitative removal of the Fmoc-tetrapeptide from the solid support was effected by treatment with 55% trifluoroacetic acid in methylene chloride. Homogeneous free tetrapeptide was obtained in 87% overall yield. The procedure is proposed to offer advantages over present solid phase methods which use acidolysis for repetitive alpha-amino group deblocking.

Amino Acid Sequence↗
PubMed1978

Replacement of the disulfide bond in oxytocin by an amide group. Synthesis and some biological properties of (cyclo-(1-L-aspartic acid,6-L-alpha,beta-diaminopropionic acid))oxytocin.

As part of a continuing investigation of the steric and electronic functions of the disulfide group in neurohypophyseal hormones on their biological activity, the synthesis of "oxytocin lactam", [cyclo-(1-aspartic acid,6-alpha,beta-diaminopropionic acid)]oxytocin, has been undertaken. The protected nonapeptide was prepared in a stepwise manner by solution techniques; after removal of side-chain protecting groups, formation of the briding amide bonds was accomplished by oxidation-reduction condensation. The analogue possesses rat uterotonic, avian vasodepressor, and rat antidiuretic potencies of 16 +/- 2, 6.6 +/- 0.6, and 5.6 +/- 3.8 units/mg, respectively.

Animals↗