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J Boger

Publications and source records attributed to J Boger.

At least 37 records · Page 2Linked to original sources
PubMed1989

X-ray studies of aspartic proteinase-statine inhibitor complexes.

The conformation of a statine-containing renin inhibitor complexed with the aspartic proteinase from the fungus Endothia parasitica (EC 3.4.23.6) has been determined by X-ray diffraction at 2.2-A resolution (R = 0.17). We describe the structure of the complex at high resolution and compare this with a 3.0-A resolution analysis of a bound inhibitor, L-364,099, containing a cyclohexylalanine analogue of statine. The inhibitors bind in extended conformations in the long active-site cleft, and the hydroxyl of the transition-state analogue, statine, interacts strongly with the catalytic aspartates via hydrogen bonds to the essential carboxyl groups. This work provides a detailed structural analysis of the role of statine in peptide inhibitors. It shows conclusively that statine should be considered a dipeptide analogue (occupying P1 to P1') despite lacking the equivalent of a P1' side chain, although other inhibitor residues (especially P2) may compensate by interacting at the unoccupied S1' specificity subsite.

Amino Acids↗
PubMed1989

2,3-Dihydro-5-benzofuranols as antioxidant-based inhibitors of leukotriene biosynthesis.

The enzymes that catalyze the oxidative metabolism of arachidonic acid have provided fertile ground for the development of useful therapeutic agents for nearly a quarter century. Inhibitors of the enzyme cyclooxygenase prevent the formation of the prostaglandins and thromboxanes and are clinically useful antiinflammatories and peripheral analgesics. More recently it has been discovered that the enzyme 5-lipoxygenase is the first step in the formation of a series of biologically important metabolites of arachidonic acid, the leukotrienes. Evidence suggests that an inhibitor of 5-lipoxygenase may be a useful therapeutic agent in the treatment of asthma, immediate hypersensitivity, and inflammation. Various antioxidants have been examined as inhibitors of 5-lipoxygenase in vitro. We were intrigued by recent reports that the 2,3-dihydro-5-benzofuranol ring system maximizes the stereoelectronic effects necessary for efficient hydrogen atom abstraction by peroxyl radicals. In this study we describe the synthesis of over 50 new 2,3-dihydro-5-benzofuranols and their biological evaluation as inhibitors of leukotriene biosynthesis in isolated human polymorphonuclear leukocytes. We show that the 2,3-dihydro-5-benzofuranol ring system, although not a potent inhibitor of leukotriene biosynthesis in itself, can provide a useful template for the design of antioxidant-based inhibitors of leukotriene biosynthesis. Furthermore, within a structural class the potency of a given analogue can be predicted on the basis of its overall calculated lipophilicity (log P). The data are interpreted in terms of a model in which the observed inhibition by this class of inhibitors is dependent on the intrinsic ability of the antioxidant to reduce the enzyme and on the fraction of the inhibitor that is partitioned into the membrane.

Antioxidants↗
PubMed1988

Renin inhibitors containing hydrophilic groups. Tetrapeptides with enhanced aqueous solubility and nanomolar potency.

Nineteen tetrapeptides containing statine (Sta) and 4-amino-5-cyclohexyl-3-hydroxypentanoic acid (ACHPA) were prepared. Solubility measurements of these compounds were carried out in H2O and in pH 7.4 phosphate buffer solution, and their partition coefficients were determined in a 1:1 1-octanol/sodium phosphate-citric acid buffer system. The tetrapeptides were tested in vitro for their ability to inhibit porcine, canine, and human plasma renins. Four compounds, 6, 12, 14, and 20, were potent inhibitors against all renins tested (IC50 = 10(-9) M). Compound 12 was administered orally to dogs and substantially inhibited plasma renin activity for up to 5 h. The addition of polar groups to the C-terminus of Sta- and ACHPA-containing tetrapeptides renders them soluble in aqueous milieu and provides a valuable tool with which to examine the role of the renin-angiotensin system in physiological and pathological circumstances.

Amino Acids↗
PubMed1988

A study of the correlation between cyclophilin binding and in vitro immunosuppressive activity of cyclosporine A and analogues.

In order to establish whether CyP is the pharmacologically relevant CsA receptor, the CyP binding v immunosuppressive activity was measured for an extensive, structurally varied group of CsA analogues. Overall, CyP binding was found to parallel immunosuppressive activity. Other than MeAla6-CsA, the few exceptions to the correlation could be ascribed to cellular metabolism. These results strongly implicate CyP or a related protein in the mechanism of action of cyclosporine.

Animals↗
PubMed1987

Renin inhibitors. Statine-containing tetrapeptides with varied hydrophobic carboxy termini.

A series of statine-containing tetrapeptides, systematically modified at the carboxy terminus with various hydrophobic aromatic groups, is described. These compounds were tested in vitro for their ability to inhibit porcine, human plasma, and purified human kidney renins. These analogues help to define optimal binding aspects in a region of the enzyme that appears to be specific for spatial arrangement of aromatic groups. Replacement of the metabolically labile Phe amide with nonpeptidal groups proved possible while achieving inhibitory potency in the nanomolar range vs. porcine kidney renin. For the compounds 6i, 6m, and 6o, a large discrepancy in potency between the human plasma and the purified human kidney renin assays was observed. This disparity does not appear to be a consequence of a previously proposed plasma binding component.

Amino Acids↗
PubMed1987

Site-specific cleavage of a fusion protein by renin.

A double-stranded synthetic oligonucleotide that codes for an amino acid sequence specifically recognized and cleaved by the endopeptidase, renin, was inserted into a plasmid expression vector. The double-stranded oligonucleotide was placed at the junction between the sequences coding for two distinct domains of a fusion protein. The vector used for this analysis expressed a 190-kD Epstein-Barr virus membrane antigen (EBV-MA)-beta-galactosidase (beta-gal) fusion protein (Beisel et al., 1985). The resultant novel protein product expressed by the new construction can be cleaved specifically by renin to yield two distinct polypeptides, EBV-MA and beta-gal, corresponding to the two domains of the original fusion protein product.

Antigens, Viral↗
PubMed1987

Comparison of a new renin inhibitor and enalaprilat in renal hypertensive dogs.

The hypotensive efficacy of a potent new renin inhibitor (N alpha-isovaleryl-L-histidyl-L-prolyl-L-phenylalanyl-L-histidyl-ACHPA+ ++-L- phenylalanyl amide) containing (3S,4S)-4-amino-5-cyclohexyl-3-hydroxy pentanoic acid (ACHPA) was compared with the converting enzyme inhibitor (enalaprilat) (MK-422) in conscious one-kidney dogs before and after tightening a renal artery clamp. Dose-response curves to 0.003 to 0.1 mg/kg/min i.v. infusions of the ACHPA-containing renin inhibitory peptide or enalaprilat (0.003-0.1 mg/kg i.v. bolus) were obtained in one-kidney dogs before and 3 days and 14 days after renal artery constriction. The ACHPA-containing renin inhibitory peptide and enalaprilat maximally decreased blood pressure by 10 +/- 2 and 9 +/- 2 mm Hg before constriction and by 12 +/- 2 and 12 +/- 4 mm Hg in dogs treated 14 days after renal artery constriction, respectively. Glomerular filtration rate and effective renal plasma flow were unaltered or slightly improved. In sharp contrast, both compounds elicited significant, dose-related decreases in blood pressure (-26 +/- 4 and -20 +/- 4 mm Hg, respectively), glomerular filtration rate (-21 +/- 3 and -23 +/- 3 ml/min), and renal plasma flow (-45 +/- 14 and -48 +/- 13 ml/min) in dogs examined 3 days after renal artery constriction. These data demonstrate that ACHPA-containing renin inhibitory peptide and enalaprilat are equally effective antihypertensive agents in dogs with renin-dependent renovascular hypertension and lend credence to the contention that the renin-angiotensin system supports renal function in hypertensive states in which renin levels are elevated.

Animals↗
PubMed1986

Antibodies of predetermined specificity to the major charged species of human interleukin 1.

The development of highly specific antisera to human interleukin 1 (IL-1) has been an elusive goal hampered mainly by the availability of only limited amounts of pure immunogen. To surmount this difficulty, three peptides of the major charged species of IL-1 (pI 6.8) were synthesized and covalently coupled to keyhole limpet hemocyanin (KLH). All three peptide-KLH conjugates raised rabbit heterologous antisera that bound intact pure IL-1 in a dose-dependent and domain-specific manner. Immunoblot analysis of crude concentrated culture supernatants with these antisera showed each of them to be highly specific for mature 18-kDa IL-1. Immunoblot analysis of monocyte lysates revealed a single 33-kDa band consistent with the size of the IL-1 precursor molecule deduced from cloned cDNA. These reagents should prove to be valuable tools in the localization and measurement of IL-1 in cells and fluids and may permit the separate study of individual IL-1 species as well as discrete domains of intact IL-1 molecules.

Animals↗
PubMed1985

Renin inhibitors. Syntheses of subnanomolar, competitive, transition-state analogue inhibitors containing a novel analogue of statine.

Analogues of the renin octapeptide substrate were synthesized in which replacement of the scissile dipeptide with (3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid (statine, Sta) transformed the substrate sequence into potent, transition-state analogue, competitive inhibitors of renin. Synthesis and incorporation of the cyclohexylalanyl analogue of Sta, (3S,4S)-4-amino-5-cyclohexyl-3-hydroxypentanoic acid (ACHPA), gave the most potent inhibitors of renin yet reported, including N-isovaleryl-L-histidyl-L-prolyl-L-phenylalanyl-L-histidyl-ACHPA-L -leucyl-L- phenylalanyl amide [Iva-His-Pro-Phe-His-ACHPA-Leu-Phe-NH2,3], with renin inhibitions of Ki = 1.6 X 10(-10) M (human kidney renin), IC50 = 1.7 X 10(-10)M (human plasma renin), IC50 = 1.9 X 10(-9)M (dog plasma renin), and IC50 = 2.1 X 10(-8) M (rat plasma renin). This inhibitor 3, containing ACHPA, was 55-76 times more potent vs. human renin than the comparable Sta-containing inhibitor 1 and 17 times more potent vs. dog renin than 1. Inhibitor 3 lowered blood pressure in sodium-deficient dogs, with in vivo potency 19 times that shown by 1, in close agreement with the relative in vitro potencies. Structure-activity results are presented that show the minimal N-terminus for these inhibitors. An ACHPA-containing pentapeptide, N-[(ethyloxy)carbonyl]-L-phenylalanyl-L- histidyl-ACHPA-L-leucyl-L-phenylalanyl amide [Etoc-Phe-His-ACHPA-Leu-Phe-NH2,8], retained subnanomolar inhibitory potency. Molecular modelling studies are described that suggested the design of ACHPA.

Amino Acids↗
PubMed1985

Multiple chemical forms of hepatitis B surface antigen produced in yeast.

Hepatitis B surface antigen (HBsAg) has been extracted from yeast cells that produce HBsAg. These cells contain the gene for surface antigen carried on a plasmid that replicates in the cells. Analysis of the yeast-derived HBsAg by sucrose gradient centrifugation and by polyacrylamide gel electrophoresis shows that the antigen that is initially released from yeast cells is a high molecular weight aggregate of the fundamental Mr 25,000 subunit. Unlike HBsAg derived from human plasma, the yeast antigen is held together by noncovalent interactions and can be dissociated in 2% NaDodSO4 without the use of reducing agents. During in vitro purification of the yeast antigen, some disulfide bonds form spontaneously between the antigen subunits, resulting in a particle composed of a mixture of monomers and disulfide-bonded dimers. Treatment with 3 M thiocyanate converts the 20-nm particles into a fully disulfide-bonded form that is not disrupted in NaDodSO4 unless a reducing agent is added. This disulfide-bonded particle resembles the naturally occurring, plasma-derived surface antigen particle, and the in vitro formed particle has been used to prepare a vaccine for humans against hepatitis B virus infection.

Alcohol Dehydrogenase↗
PubMed1985

Induction of hepatitis A virus-neutralizing antibody by a virus-specific synthetic peptide.

Comparative surface feature analyses of the VP1 sequences of hepatitis A virus (HAV) and poliovirus type 1 allowed an alignment of the two sequences and an identification of probable HAV neutralization antigenic sites. A synthetic peptide containing the HAV-specific amino acid sequence of one of these sites induced anti-HAV-neutralizing antibodies. It is concluded that a structural homology exists between the two viruses, despite minimal primary sequence conservation.

Amino Acid Sequence↗
PubMed1985

Interaction of mouse submaxillary gland renin with a statine-containing, subnanomolar, competitive inhibitor.

The interaction between mouse submaxillary gland renin and a statine-containing, iodinated substrate analog inhibitor was studied. The compound, 1 (Boc-His-Pro-Phe-(4-iodo)-Phe-Sta-Leu-Phe-NH2, Sta = (3S,4S)-4-amino-3-hydroxy-6-methyl-heptanoic acid), a statine-containing analog of the renin substrate octapeptide, was a competitive inhibitor of cleavage of synthetic tetradecapeptide renin substrate by mouse submaxillary gland renin, with a Ki of 6.2 x 10(-10) M (pH 7.2, 37 degrees C). Titration of the partial quenching of the tryptophan fluorescence of the enzyme by 1 revealed tight binding with a dissociation constant less than 3 nM and a binding stoichiometry of one mole 1 per mole enzyme. The time course of tight binding of 1 to mouse renin appeared to be fast, with kON greater than or equal to 1.3 x 10(6) s-1 M-1. The UV difference spectrum generated upon binding of 1 to mouse renin had two prominent features: a strong, broad band that had a minimum at 242 nm with delta epsilon (242) = -19,500 cm-1 M-1, and a triplet of enhanced bands centered at 286 nm with delta epsilon (286) about +1100 cm-1 M-1. The strong, broad, negative band was similar to the difference between the UV absorbance of 1 in methanol and in 0.1 M citrate phosphate pH 7.2. A structure-activity correlation for analogs of 1 showed some moieties of 1 that are important for potent inhibition of mouse renin. The inhibition data for these compounds versus human kidney renin suggested that the solution of the crystal structure of 1 bound to mouse renin will provide useful information for the design of inhibitors of human kidney renin.

Amino Acid Sequence↗
PubMed1984

Preliminary X-ray crystallographic data on mouse submaxillary gland renin and renin-inhibitor complexes.

We have crystallized renin from the submaxillary gland of male mice, both in its native state, and in binary complex with transition-state analog inhibitors. The best of the many crystal forms examined consisted of tetragonal bipyramids with space group symmetry P41 21 2 (or its enantiomorph) and unit cell dimensions a = b = 91.4 A, c = 211.6 A; alpha = beta = gamma = 90 degrees. This tetragonal form was compatible with both inhibited and uninhibited renin. Two of the inhibitors used were synthesized as iodinated analogs; their binary complexes with renin may serve as single-site rational heavy atom derivatives. X-ray data beyond 2.8-A resolution have been collected by oscillation photography using the Cornell High Energy Synchrotron Source in Ithaca, NY.

Amino Acid Sequence↗
PubMed1984

Sunscreens: efficacy, use, and misuse.

To provide a rational approach in the selection and use of sunscreens, we have reviewed some aspects of sun damage, the importance of genetically determined skin types, and the skin's natural protective mechanisms. In this review, we classify sunscreens, explain the sun protection factor (SPF), discuss characteristic features of specific sunscreens, supply guidelines for tanning while minimizing skin damage, and indicate which products and devices may be harmful to consumers.

4-Aminobenzoic Acid↗
PubMed1977

To stabilize a transition state.

Inspection of the active sites of the many enzymes whose structures are known at high resolution leads to the unsurprising conclusion that an enzyme may provide an environment that exquisitely stabilizes the transition state for an elementary catalytic step that is expected to be difficult. In an effort both to mimic such an environment and to have the opportunity of investigating the thermodynamic and kinetic consequences of juxtaposing polar and non-polar loci in the same molecule, we have synthesized several specifically functionalized alpha-cyclodextrins. One of these is designed to stabilize the trigonal bipyramidal transition state for an in-line displacement at the phosphorus of a phosphate monoester. This cyclodextrin contains three symmetrically disposed ammonium groups on the 'top' (at C-6) of the hydrophobic cavity formed by the hexa-glucose torus and the remaining 15 hydroxy groups are methylated. The thermodynamic consequences of adjacent hydrophobic and hydrogen-bonding and/or electrostatic binding sites are investigated using several charged and uncharged ligands. The feasibility of building host species explicitly to stabilize reaction transition states is discussed.

Dextrins↗
PubMed1977

Evaluation of cardiac size in chronic bronchitis and pulmonary emphysema.

The accuracy of interobserver variability of roentgenographic analysis for cardiac size in patients dying with chronic bronchitis and pulmonary emphysema were correlated with pathologic data derived from special studies. Three trained observers were able to accurately and consistently diagnose chronic bronchitis and pulmonary emphysema and to detect cardiomegaly on the chest x-ray film. The best criteria for chronic bronchitis and pulmonary emphysema were those of overinflation; however, none of the roentgenographic criteria usually suggested for the specific diagnosis of right ventricular or left ventricular hypertrophy were found to be reliable. The inaccuracy and interobserver variability in the detection of enlargement of specific chambers make it evident that the usual criteria are not valid and that roentgenographic appraisal of cardiac size in these patients in limited to findings of normalcy or cardiomegaly.

Autopsy↗