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E Verner

Publications and source records attributed to E Verner.

18 recordsLinked to original sources
PubMed2001

Exploiting subsite S1 of trypsin-like serine proteases for selectivity: potent and selective inhibitors of urokinase-type plasminogen activator.

A nonselective inhibitor of trypsin-like serine proteases, 2-(2-hydroxybiphenyl-3-yl)-1H-indole-5-carboxamidine (1) (Verner, E.; Katz, B. A.; Spencer, J.; Allen, D.; Hataye, J.; Hruzewicz, W.; Hui, H. C.; Kolesnikov, A.; Li, Y.; Luong, C.; Martelli, A.; Radika. K.; Rai, R.; She, M.; Shrader, W.; Sprengeler, P. A.; Trapp, S.; Wang, J.; Young, W. B.; Mackman, R. L. J. Med. Chem. 2001, 44, 2753-2771) has been optimized through minor structural changes on the S1 binding group to afford remarkably selective and potent inhibitors of urokinase-type plasminogen activator (uPA). The trypsin-like serine proteases(1) that comprise drug targets can be broadly categorized into two subfamilies, those with Ser190 and those with Ala190. A single-atom modification, for example, replacement of hydrogen for chlorine at the 6-position of the 5-amidinoindole P1 group on 1, generated up to 6700-fold selectivity toward the Ser190 enzymes and against the Ala190 enzymes. The larger chlorine atom displaces a water molecule (H(2)O1(S1)) that binds near residue 190 in all the complexes of 1, and related inhibitors, in uPA, thrombin, and trypsin. The water molecule, H(2)O1(S1), in both the Ser190 or Ala190 enzymes, hydrogen bonds with the amidine N1 nitrogen of the inhibitor. When it is displaced, a reduction in affinity toward the Ala190 enzymes is observed due to the amidine N1 nitrogen of the bound inhibitor being deprived of a key hydrogen-bonding partner. In the Ser190 enzymes the affinity is maintained since the serine hydroxyl oxygen O gamma(Ser190) compensates for the displaced water molecule. High-resolution crystallography provided evidence for the displacement of the water molecule and validated the design rationale. In summation, a novel and powerful method for engineering selectivity toward Ser190 proteases and against Ala190 proteases without substantially increasing molecular weight is described.

Amidines↗
PubMed2001

Development of serine protease inhibitors displaying a multicentered short (<2.3 A) hydrogen bond binding mode: inhibitors of urokinase-type plasminogen activator and factor Xa.

Novel scaffolds that bind to serine proteases through a unique network of short hydrogen bonds to the catalytic Ser195 have been developed. The resulting potent serine protease inhibitors were designed from lead molecule 2-(2-hydroxyphenyl)1H-benzoimidazole-5-carboxamidine, 6b, which is known to display several modes of binding. For instance, 6b can recruit zinc and bind in a manner similar to that reported by bis(5-amidino-2-benzimidazolyl)methane (BABIM) (Nature 1998, 391, 608-612).(1) Alternatively, 6b can bind in the absence of zinc through a multicentered network of short (<2.3 A) hydrogen bonds. The lead structure was optimized in the zinc-independent binding mode toward a panel of six human serine proteases to yield optimized inhibitors such as 2-(3-bromo-2-hydroxy-5-methylphenyl)-1H-indole-5-carboxamidine, 22a, and 2-(2-hydroxybiphenyl-3-yl)-1H-indole-5-carboxamidine, 22f. Structure-activity relationships determined that, apart from the amidine function, an indole or benzimidazole and an ortho substituted phenol group were also essential components for optimal potency. The affinities (K(i)) of 22a and 22f, for example, bearing these groups ranged from 8 to 600 nM toward a panel of six human serine proteases. High-resolution crystal structures revealed that the binding mode of these molecules in several of the enzymes was identical to that of 6b and involved short (<2.3 A) hydrogen bonds among the inhibitor hydroxyl oxygen, Ser195, and a water molecule trapped in the oxyanion hole. In summation, novel and potent trypsin-like serine protease inhibitors possessing a unique mode of binding have been discovered.

Amidines↗
PubMed2001

A novel serine protease inhibition motif involving a multi-centered short hydrogen bonding network at the active site.

We describe a new serine protease inhibition motif in which binding is mediated by a cluster of very short hydrogen bonds (<2.3 A) at the active site. This protease-inhibitor binding paradigm is observed at high resolution in a large set of crystal structures of trypsin, thrombin, and urokinase-type plasminogen activator (uPA) bound with a series of small molecule inhibitors (2-(2-phenol)indoles and 2-(2-phenol)benzimidazoles). In each complex there are eight enzyme-inhibitor or enzyme-water-inhibitor hydrogen bonds at the active site, three of which are very short. These short hydrogen bonds connect a triangle of oxygen atoms comprising O(gamma)(Ser195), a water molecule co-bound in the oxyanion hole (H(2)O(oxy)), and the phenolate oxygen atom of the inhibitor (O6'). Two of the other hydrogen bonds between the inhibitor and active site of the trypsin and uPA complexes become short in the thrombin counterparts, extending the three-centered short hydrogen-bonding array into a tetrahedral array of atoms (three oxygen and one nitrogen) involved in short hydrogen bonds. In the uPA complexes, the extensive hydrogen-bonding interactions at the active site prevent the inhibitor S1 amidine from forming direct hydrogen bonds with Asp189 because the S1 site is deeper in uPA than in trypsin or thrombin. Ionization equilibria at the active site associated with inhibitor binding are probed through determination and comparison of structures over a wide range of pH (3.5 to 11.4) of thrombin complexes and of trypsin complexes in three different crystal forms. The high-pH trypsin-inhibitor structures suggest that His57 is protonated at pH values as high as 9.5. The pH-dependent inhibition of trypsin, thrombin, uPA and factor Xa by 2-(2-phenol)benzimidazole analogs in which the pK(a) of the phenol group is modulated is shown to be consistent with a binding process involving ionization of both the inhibitor and the enzyme. These data further suggest that the pK(a) of His57 of each protease in the unbound state in solution is about the same, approximately 6.8. By comparing inhibition constants (K(i) values), inhibitor solubilities, inhibitor conformational energies and corresponding structures of short and normal hydrogen bond-mediated complexes, we have estimated the contribution of the short hydrogen bond networks to inhibitor affinity ( approximately 1.7 kcal/mol). The structures and K(i) values associated with the short hydrogen-bonding motif are compared with those corresponding to an alternate, Zn(2+)-mediated inhibition motif at the active site. Structural differences among apo-enzymes, enzyme-inhibitor and enzyme-inhibitor-Zn(2+) complexes are discussed in the context of affinity determinants, selectivity development, and structure-based inhibitor design.

Amino Acid Motifs↗
PubMed2001

Engineering inhibitors highly selective for the S1 sites of Ser190 trypsin-like serine protease drug targets.

BACKGROUND: Involved or implicated in a wide spectrum of diseases, trypsin-like serine proteases comprise well studied drug targets and anti-targets that can be subdivided into two major classes. In one class there is a serine at position 190 at the S1 site, as in urokinase type plasminogen activator (urokinase or uPA) and factor VIIa, and in the other there is an alanine at 190, as in tissue type plasminogen activator (tPA) and factor Xa. A hydrogen bond unique to Ser190 protease-arylamidine complexes between O gamma(Ser190) and the inhibitor amidine confers an intrinsic preference for such inhibitors toward Ser190 proteases over Ala190 counterparts. RESULTS: Based on the structural differences between the S1 sites of Ser190 and Ala190 protease-arylamidine complexes, we amplified the selectivity of amidine inhibitors toward uPA and against tPA, by factors as high as 220-fold, by incorporating a halo group ortho to the amidine of a lead inhibitor scaffold. Comparison of K(i) values of such halo-substituted and parent inhibitors toward a panel of Ser190 and Ala190 proteases demonstrates pronounced selectivity of the halo analogs for Ser190 proteases over Ala190 counterparts. Crystal structures of Ser190 proteases, uPA and trypsin, and of an Ala190 counterpart, thrombin, bound by a set of ortho (halo, amidino) aryl inhibitors and of non-halo parents reveal the structural basis of the exquisite selectivity and validate the design principle. CONCLUSIONS: Remarkable selectivity enhancements of exceptionally small inhibitors are achieved toward the uPA target over the highly similar tPA anti-target through a single atom substitution on an otherwise relatively non-selective scaffold. Overall selectivities for uPA over tPA as high as 980-fold at physiological pH were realized. The increase in selectivity results from the displacement of a single bound water molecule common to the S1 site of both the uPA target and the tPA anti-target because of the ensuing deficit in hydrogen bonding of the arylamidine inhibitor when bound in the Ala190 protease anti-target.

Animals↗
PubMed1989

Skin-isolated, community-acquired Staphylococcus aureus: in vitro resistance to methicillin and erythromycin.

During a 10-month period, skin culture specimens were taken from 1680 healthy outpatients with a variety of community-acquired skin infections. Staphylococcus aureus was found in 1035 (61.6%) of these patients. In vitro resistance to methicillin and erythromycin was 1.0% and 42.9%, respectively. Resistance rates to erythromycin in patients with furunculosis and impetigo were 51.5% and 26.2%, respectively (p less than 0.001). The emergence of erythromycin-resistant strains may be the result of widespread use of this drug in our geographic area. There is also the possibility that certain bacteriologic features associated with erythromycin resistance may foster the development of furunculosis.

Adolescent↗
PubMed1988

Diagnostic and therapeutic approach to Ethiopian immigrants seropositive for syphilis.

Serologic tests for syphilis are frequently positive in Ethiopian Jewish immigrants in Israel. Forty-three of 358 adults (greater than 15 years of age) examined were found to have positive treponemal tests. Of the 418 children (1 to 15 years of age) none were found to have positive treponemal serology. Forty seropositive adults were examined for signs of tertiary syphilis and underwent lumbar puncture. No evidence of skin or cardiovascular involvement of tertiary syphilis was found. In three patients whose cerebrospinal fluid (CSF) was reactive in treponemal tests, there was no evidence of neuropsychiatric involvement. CSF cell count and protein content were normal in all three, and VDRL in the CSF was negative. None of the subjects was found to have stigmata of congenital syphilis. Negative serological findings in all the children led us to hypothesize whether the disease in question is venereal syphilis with an unusual course rather than endemic syphilis or yaws, both of which are known to exist in Africa. Due to the apparent benign course of syphilis in this ethnic group and recent evidence that lumbar puncture is not mandatory in patients with latent syphilis or asymptomatic neurosyphilis, we suggest that CSF should not be routinely examined in these patients. In view of the recommendations in the literature and the data that we have collected, we strongly feel that treatment with weekly i.m. injections of 2.4 x 10(6) u benzathine penicillin for a 3-week period is sufficient.

Adolescent↗
PubMed1980

A comparative study of breast cancer in the black and white populations of two inner-city hospitals.

A comparative study of breast cancer was made among black and white populations admitted to two inner-city hospitals from 1971 through 1976, inclusive. There were 306 patients in the study group of which 162 were black and 144 were white. Age, sex, color, duration of illness, different quadrants of breast involved, staging of cancer, histological diagnosis, treatment given, and incidence of recurrence were studied in each group. A statistically higher incidence of cancer of the breast was found among the black patients in the groups aged 30--50 years and 70--80 years, as compared to the white population. All other parametes studied showed no statistical differences.

Adolescent↗
PubMed1977

Intestinal absorption of 47Ca in elderly patients with osteoporosis, Paget's disease and osteomalacia. Effects of calcitonin, oestrogen and vitamin D2.

The intestinal absorption of 47Ca was studied in elderly patients. A standard dose of 10 muCi of 47Ca was given orally. The radioactivity was measured in the plasma, and expressed as percentage of the administered dose per litre plasma. As a control group served 12 patients aged 60-80 years, hospitalized for observation for various reasons, receiving no medical treatment and not suffering from any known metabolic bone diseases or other metabolic pathological conditions. Results of kinetic curves demonstrate in elderly patients a decreased absorption with maximum specific activity in plasma reached at 120 min, when compared to data from the literature referring to a group of young people with a mean age of 35 years. Oestrogen treatment, given as ethinyl oestradiol 10 mug once daily per os for 10 days proved to increase 47Ca absorption as was demonstrated in 2 patients with osteoporosis. The effect of calcitonin (160 MRC units given 45 min before the test) on calcium absorption, in 5 patients with Paget's disease or osteoporosis appears as biphasic: in the first hour depressing calcium absorption and then in the second and third hours increasing the absorption, suggesting a hyperparathyroid state secondary to the calcitonin effect. The vitamin D2 treatment proved to increase calcium absorption.

Aged↗
PubMedDate not supplied

Zollinger-Ellison syndrome associated with a renal gastrinoma in a child.

Renal gastrinoma has not been previously reported. A 12-year-old boy with Zollinger-Ellison syndrome was found to have a renal tumor. No other tumor was detectable by imaging techniques, and selective venous sampling for gastrin showed a significant renal vein to vena cava gradient. Nephrectomy was performed, and examination of the tumor showed typical histologic features of an endocrine tumor. G cells were apparent by electron microscopy, and immunoperoxidase staining for gastrin, neuron-specific enolase, and chromogranin were positive. The gastrin content was unusually low for gastrinomas: 128 pg/g. Following nephrectomy, fasting gastrin and secretin stimulation testing were normal. Basal acidity was reduced by 60% but remained elevated at 39 mmol H +/h (hydrogen ion per hour). We speculate that renal gastrinoma may be characterized by uniquely poor gastrin storage and that curative resection of all gastrinoma tissue may not necessarily be associated with immediate complete suppression of hyperacidity.

Child↗