Ruth F. Nutt

HIV-1 protease specificity of peptide cleavage is sufficient for processing of gag and pol polyproteins.

The mature proteins of retroviruses originate as a result of proteolytic cleavages of polyprotein precursors. Retroviruses encode proteases responsible for several of these processing events, making them potential antiviral drug targets. A 99-amino acid HIV-1 protease, produced by chemical synthesis or by expression in bacteria, is shown here to hydrolyze peptides corresponding to all of the known cleavage sites in the HIV-1 gag and pol polyproteins. It does not hydrolyze peptides corresponding to an env cleavage site or a distantly related retroviral gag cleavage site.

Vasodilator profile of synthetic atrial natriuretic factor

The vasodilator profile of synthetic atrial natriuretic factor (ANF) was characterized using isolated vascular preparations. Nanomolar concentrations of ANF relaxed rabbit aortic rings contracted by serotonin, histamine, methoxamine or angiotensin II. The synthetic peptide was most effective (IC50 = 1.3 X 10(-10) M) in relaxing the tonic, intrinsic contractions of the rabbit facial vein. ANF was poorly active against K+-contracted aortic rings or the phasic contractions of the rat portal vein. A similar vasodilator profile was obtained for sodium nitroprusside but not papaverine, hydralazine, adenosine or nifedipine. This first demonstration of the vascular activity of synthetic ANF depicts this substance as a nonselective vasodilator of agonist-induced contractions. The observed similarities in the vasodilator activity of ANF and sodium nitroprusside suggest a common mechanism of action.

Highly active cyclic and bicyclic somatostatin analogues of reduced ring size

THE biological activity of an organic compound represents the sum of several properties, including solubility, absorption, transport, plasma protein binding, metabolism and receptor binding. The degree of molecular flexibility may affect these properties in different ways. Our approach to the design of somatostatin analogues with reduced susceptibility to metabolic inactivation has been both to eliminate those amino acids which are not required for biological activity and to increase the rigidity of the molecule. We report here the preparation of conformationally constrained analogues of somatostatin (Fig. 1, IIa and III) which are highly active inhibitors of the release of insulin, glucagon and growth hormone in vivo. Analogue III (Fig. 1), which retains only four of the amino acids of the natural hormone (sequence 7–10), is relatively resistant to the action of trypsin in vitro.

A super active cyclic hexapeptide analog of somatostatin

The cyclic hexapeptide, cyclo (Pro-Phe-D-Trp-Lys-Thr-Phe), I, has been shown to have the biological properties of somatostatin. We now report structure-activity studies which optimize the potency of this cyclic hexapeptide series with the synthesis of cyclo (N-Me-Ala-Tyr-D-Trp-Lys-Val-Phe), II, which is 50-100 times more potent than somatostatin for the inhibition of insulin, glucagon and growth hormone release. The hydroxyl group of tyrosine is seen to lend a 10-fold enhancement to the potency. Potency also is found to be correlated with hydrophobicity. II is found to improve the control of postprandial hyperglycemia in diabetic animals when given in combination with insulin. The analog is found to be quite stable in the blood and in the gastrointestinal tract, but the bioavailability after oral administration is only 1-3%. The biological properties and long duration of II should allow clinical evaluation of the inhibition of glucagon release as an adjunct to insulin in the treatment of patients with diabetes.

Identification of high affinity endothelin-1 receptor subtypes in human tissues

Two subtypes of the high affinity endothelin-1 (ET-1) receptor were identified in human tissue, and were distinguished by their differential affinities for sarafotoxin S6c (S6c). Uterus contains mostly the ETA subtype, with low affinity for S6c (Ki greater than 7300 nM), while the predominant subtype in hippocampus is ETB, with high affinity for S6c (Ki = 0.25 nM). These subtypes also have different affinities for [Ala1,3,11,15]-ET-1, which was found to be ETB selective. The two subtypes distinguished by these ligands in human tissue correspond to the subtypes previously identified in rat. Differential stimulation of phosphatidyl inositol turnover in rat tissue slices by ET-1 and S6c indicates that both ETA and ETB subtypes represent functional receptors.

Comparative vasoactive effects of native and synthetic atrial natriuretic factor (ANF)

The presence of a natriuretic factor in mammals atria has been confirmed by many laboratories. In addition to its natriuretic and diuretic activities, atrial preparation of uncertain degree of purification are known to contain a vasoactive substance. By the use of pure atrial natriuretic factor of known amino acid sequence and its synthetic homologue we have presented strong evidences suggesting that natriuretic and vasoactive activities are indeed mediated by the same peptide. As this peptide has not yet been detected in the circulation, its actual physiological relevance remains to be elucidated.

Concise total synthesis of the prolyl endopeptidase inhibitor eurystatin A via a novel Passerini reaction-deprotection-acyl migration strategy †

Abstract The Passerini reaction between suitably protected alaninal, leucine isonitrile, and ornithine components delivered adducts 10a , b in high yield. Orthogonal N -deprotection of 10a led, via a smooth O - to N -acyl migration, to 11 , which constitutes the entire skeleton of the eurystatins. Subsequent deprotection, macrocyclization, elaboration, and final oxidation steps efficiently afforded eurystatin A 1a in high overall yield.

Analysis of large screening data sets via adaptively grown phylogenetic-like trees.

As the use of high-throughput screening systems becomes more routine in the drug discovery process, there is an increasing need for fast and reliable analysis of the massive amounts of the resulting data. At the forefront of the methods used is data reduction, often assisted by cluster analysis. Activity thresholds reduce the data set under investigation to manageable sizes while clustering enables the detection of natural groups in that reduced subset, thereby revealing families of compounds that exhibit increased activity toward a specific biological target. The above process, designed to handle primarily data sets of sizes much smaller than the ones currently produced by high-throughput screening systems, has become one of the main bottlenecks of the modern drug discovery process. In addition to being fragmented and heavily dependent on human experts, it also ignores all screening information related to compounds with activity less than the threshold chosen and thus, in the best case, can only hope to discover a subset of the knowledge available in the screening data sets. To address the deficiencies of the current screening data analysis process the authors have developed a new method that analyzes thoroughly large screening data sets. In this report we describe in detail this new approach and present its main differences with the methods currently in use. Further, we analyze a well-known, publicly available data set using the proposed method. Our experimental results show that the proposed method can improve significantly both the ease of extraction and amount of knowledge discovered from screening data sets.

Design and synthesis of a novel class of thrombin inhibitors incorporating heterocyclic dipeptide surrogates

Abstract Several potent and selective inhibitors of thrombin incorporating novel heterocyclic peptide surrogates in the P3-P2 position of peptidyl argininals have been discovered. Illustrated in this article are three classes of heterocycles: pyridones, uracils, and pyrimidinones. The synthesis and biological activities of these unique aromatic heterocyclic derivatives are reported herein.

Novel and general method for the preparation of peptidyl argininals

Abstract A general method for the synthesis of peptidyl argininals was developed which utilizes the novel building block N g -nitro-L-argininal ethyl aminal·HCl. The final aldehyde structure is generated by hydrolysis of the peptidic aminal moiety and can be applied to highly functionalized peptidic structures. The method is amenable to the preparation of large quantities of enantiomerically pure peptidyl argininals and was applied to the synthesis of two potent thrombin inhibitors.