Balekudru Devadas - Academia.edu (original) (raw)
Papers by Balekudru Devadas
Journal of the American Chemical Society, 1990
Journal of the American Chemical Society, 1987
The Journal of Organic Chemistry, 1987
Synthetic Communications, 1995
ABSTRACT Syntheses of novel 3-ethynyl (8), 3-vinyl (10) and 3-acetoxy (13)-2′-deoxy-3-deazauridin... more ABSTRACT Syntheses of novel 3-ethynyl (8), 3-vinyl (10) and 3-acetoxy (13)-2′-deoxy-3-deazauridine analogs starting from the protected 2′-deoxy-3-deazauridine derivative 4 are described.
Journal of the American Chemical Society, 1986
The captodative free radical 3,5,5-trimethyl-2-oxomorpholin-3-yl (1, TM-3) from bond homolysis of... more The captodative free radical 3,5,5-trimethyl-2-oxomorpholin-3-yl (1, TM-3) from bond homolysis of meso-and dl-bi(3,5,5-
Tetrahedron Letters, 1993
ABSTRACT
The Journal of biological chemistry, Jan 15, 1992
Covalent attachment of myristic acid (C14:0) to the amino-terminal glycine residue of a variety o... more Covalent attachment of myristic acid (C14:0) to the amino-terminal glycine residue of a variety of eukaryotic cellular and viral proteins can have a profound influence on their biological properties. The enzyme that catalyzes this modification, myristoyl-CoA-protein N-myristoyltransferase (NMT), has been identified as a potential target for antiviral and antifungal therapy. Its reaction mechanism is ordered Bi Bi with myristoyl-CoA binding occurring before binding of peptide and CoA release preceding release of myristoylpeptide. Perturbations in the binding of its acyl-CoA substrate would therefore be expected to have an important influence on catalysis. We have synthesized 56 analogs of myristic acid (C14:0) to further characterize the acyl-CoA binding site of Saccharomyces cerevisiae NMT. The activity of fatty acid analogs was assessed using a coupled in vitro assay system that employed the reportedly nonspecific Pseudomonas acyl-CoA synthetase, purified S. cerevisiae NMT, and oct...
Journal of medicinal chemistry, Jan 12, 1998
A new class of biologically active nonpeptidic inhibitors of Candida albicans NMT has been synthe... more A new class of biologically active nonpeptidic inhibitors of Candida albicans NMT has been synthesized starting from the octapeptide ALYASKLS-NH2 (2). The synthetic strategy entailed the preparation of novel protected Ser-Lys mimics 9 and 12 from (S)- or (R)-3-iodotyrosine and then grafting key enzyme recognition elements in a stepwise manner. Like 2, compounds 16, 17, and 18 are competitive Candida NMT inhibitors that bind to the peptide recognition site of the enzyme. Moreover, 16-18 have an affinity comparable to that of 2 even though they are devoid of peptide bonds. In contrast to 2, these nonpeptidic inhibitors exhibit antifungal activity.
Proceedings of the National Academy of Sciences, 1990
Covalent attachment of myristic acid (C14:0) to the NH2-terminal glycine residue of a number of c... more Covalent attachment of myristic acid (C14:0) to the NH2-terminal glycine residue of a number of cellular, viral, and oncogene-encoded proteins is essential for full expression of their biological function. Substitution of oxygen for methylene groups in this fatty acid does not produce a significant change in chain length or stereochemistry but does result in a reduction in hydrophobicity. These heteroatom-containing analogs serve as alternative substrates for ammalian myristoyl-CoA:protein N-myristoyltransferase (EC 2.3.1.97) and offer the opportunity to explore structure/function relationships of Abbreviations: FA, fatty acid; NMT, myristoyl-CoA:protein N-myristoyltransferase; RaSV, Rasheed sarcoma virus; C/M, cytosolic to membrane.
Proceedings of the National Academy of Sciences, 1991
Covalent linkage of myristate (tetradecanoate; 14:0) to the NH2-terminal glycine residue of the h... more Covalent linkage of myristate (tetradecanoate; 14:0) to the NH2-terminal glycine residue of the human immunodeficiency virus 1 (HIV-1) 55-kDa gag polyprotein precursor (Pr55gag) is necessary for its proteolytic processing and viral assembly. We have shown recently that several analogs of myristate in which a methylene group is replaced by a single oxygen or sulfur atom are substrates for Saccharomyces cerevisiae and mammalian myristoyl-CoA:protein N-myristoyltransferase (EC 2.3.1.97; NMT) despite their reduced hydrophobicity. Some inhibit HIV-1 replication in acutely infected CD4+H9 cells without accompanying cellular toxicity. To examine the mechanism of their antiviral effects, we performed labeling studies with two analogs, 12-methoxydodecanoate (13-oxamyristate; 13-OxaMyr) and 5-octyloxypentanoate (6-oxamyristate; 6-OxaMyr), the former being much more effective than the latter in blocking virus production. [3H]Myristate and [3H]13-OxaMyr were incorporated into Pr55gag with comparable efficiency when it was coexpressed with S. cerevisiae NMT in Escherichia coli. [3H]6-OxaMyr was not incorporated, even though its substrate properties in vitro were similar to those of 13-OxaMyr and myristate. [3H]13-OxaMyr, but not [3H]6-OxaMyr, was also efficiently incorporated into HIV-1 Pr55gag and nef (negative factor) in chronically infected H9 cells. Analog incorporation produced a redistribution of Pr55gag from membrane to cytosolic fractions and markedly decreased its proteolytic processing by viral protease. 13-OxaMyr and 3'-azido-3'-deoxythymidine (AZT) act synergistically to reduce virus production in acutely infected H9 cells. Unlike AZT, the analog is able to inhibit virus production (up to 70%) in chronically infected H9 cells. Moreover, the inhibitory effect lasts 6-8 days. These results suggest that (i) its mechanism of action is distinct from that of AZT and involves a late step in virus assembly; (ii) the analog may allow reduction in the dose of AZT required to affect viral replication; and (iii) combinations of analog and HIV-1 protease inhibitors may have synergistic effects on the processing of Pr55gag.
Microbiology, 1997
Myristoyl-CoA: protein N-myristoyltransf erase (Nmt) catalyses the covalent attachment of myrista... more Myristoyl-CoA: protein N-myristoyltransf erase (Nmt) catalyses the covalent attachment of myristate to the N-terminal glycine of a small subset of cellular proteins produced during vegetative growth of Candida albicans. nmt447D is a mutant NMT allele encoding an enzyme with a G l F 7 4 Asp substitution and reduced affinity for myristoyl-CoA. Among isogenic NMTINMT, NMTlhnmt and nmthlnmt447D strains, only nmthlnmt447D cells require myristate for growth on yeast/peptone/dextrose media (YPD) at 24 or 37 "C. When switched from YPD/myristate to YPD alone, 60% of the organisms die within 4 h.
The Journal of Organic Chemistry, 1991
... Tianbao Lu,* B. Devadas,l Steven P. Adams,* Jeffrey I. Gordon,+ and George W. Gokel*J Departm... more ... Tianbao Lu,* B. Devadas,l Steven P. Adams,* Jeffrey I. Gordon,+ and George W. Gokel*J Department of Chemistry, Uniuersity of Miami, Coral Gables, Florida 33124, Departments of Medicine and Biochemistry and Molecular Biophysics, Washington ... L. Zzu. (18) Kotva, R.; Cerny ...
Journal of Medicinal Chemistry, 1995
Design and Syntheses of Potent and Selective Dipeptide Inhibitors of Candida albicans Myristoyl-C... more Design and Syntheses of Potent and Selective Dipeptide Inhibitors of Candida albicans Myristoyl-CoAProtein N-Myris t oyltransferase ... Balekudru Devadas,* Mark E. Zupec, Sandra K. Freeman,' David L. Brown, Srinivasan Nagarajan, James A. Sikorski, Charles A. ...
Journal of Medicinal Chemistry, 1997
A new class of antifungal agents has been discovered which exert their activity by blockade of my... more A new class of antifungal agents has been discovered which exert their activity by blockade of myristoylCoA: protein N-myristoyltransferase (NMT; EC 2.1.3.97). Genetic experiments have established that NMT is needed to maintain the viability of Candida albicans and Cryptococcus neoformans,the two principal causes of systemic fungal infections in immunocompromised humans. Beginning with a weak octapeptide inhibitor ALYASKLS-NH2 (2, Ki = 15.3 +/- 6.4 microM), a series of imidazole-substituted Ser-Lys dipeptide amides have been designed and synthesized as potent and selective inhibitors of Candida albicans NMT. The strategy that led to these inhibitors evolved from the identification of those functional groups in the high-affinity octapeptide substrate GLYASKLS-NH2 1a necessary for tight binding, truncation of the C-terminus, replacement of the four amino acids at the N-terminus by a spacer group, and substitution of the glycine amino group with an N-linked 2-methylimidazole moiety. Initial structure-activity studies led to the identification of 31 as a potent and selective peptidomimetic inhibitor with an IC50 of 56 nM and 250-fold selectivity versus human NMT. 2-Methylimidazole as the N-terminal amine replacement in combination with a 4-substituted phenacetyl moiety imparts remarkable potency and selectivity to this novel class of inhibitors. The (S,S) stereochemistry of serine and lysine residues is critical for the inhibitory activity, since the (R,R) enantiomer 40 is 10(3)-fold less active than the (S,S) isomer 31. The inhibitory profile exhibited by this new class of NMT ligands is a function of the pKa of the imidazole substituent as illustrated by the benzimidazole analog 35 which is about 10-fold less potent than 31. The measured pKa (7.1 +/- 0.5) of 2-methylimidazole in 31 is comparable with the estimated pKa (approximately 8.0) of the glycyl residue in the high-affinity substrate 1a. Groups bulkier than methyl, such as ethyl, isopropyl, or iodo, at the imidazole 2-position have a detrimental effect on potency. Further refinement of 31 by grafting an alpha-methyl group at the benzylic position adjacent to the serine residue led to 61 with an IC50 of 40 nM. Subsequent chiral chromatography of 61 culminated in the discovery of the most potent Candida NMT inhibitor 61a reported to date with an IC50 of 20 nM and 400-fold selectivity versus the human enzyme. Both 31 and 61a are competitive inhibitors of Candida NMT with respect to the octapeptide substrate GNAASARR-NH2 with Ki(app) = 30 and 27 nM, respectively. The potency and selectivity displayed by these inhibitors are dependent upon the size and orientation of the alpha-substituent. An alpha-methyl group with the R configuration corresponding to the (S)-methyl-4-alanine in 2 confers maximum potency and selectivity. Structural modification of 31 and 61 by appending an (S)-carboxyl group beta to the cyclohexyl moiety provided the less potent tripeptide inhibitors 73a and 73b with an IC50 of 1.45 +/- 0.08 and 0.38 +/- 0.03 microM, respectively. However, these tripeptides (73a and 73b) exhibited a pronounced selectivity of 560- and 2200-fold versus the human NMT. More importantly 73a displayed fungistatic activity against C albicans with an EC50 of 51 +/- 17 microM in cell culture. Compound 73b also exhibited a similar antifungal activity. An Arf protein gel mobility shift assay for monitoring intracellular myristoylation revealed that a single dose of 200 microM of 73a or 73b produced < 50% reduction in Arf N-myristoylation, after 24 and 48 h, consistent with their fungistatic rather than fungicidal activity. In contrast, the enantiomer 73d which had an IC50 > 1000 microM against C. albicans NMT did not exhibit antifungal activity and produced no detectable reduction in Arf N-myristoylation in cultures of C. albicans. These studies confirm that the observed antifungal activity of 73a and 73b is due to the attenuation of NMT activity and that NMT represents an attractive tar
Journal of Medicinal Chemistry, 1997
MyristoylCoA:protein N-myristoyltransferase (NMT) covalently attaches the 14-carbon saturated fat... more MyristoylCoA:protein N-myristoyltransferase (NMT) covalently attaches the 14-carbon saturated fatty acid myristate, via an amide bond, to the N-terminal glycine residues of a variety of cellular proteins. Genetic studies have shown that NMT is essential for the viability of the principal ...
Journal of Labelled Compounds and Radiopharmaceuticals, 1991
Page 1. Journal of Labelled Compounds and Radiophamceuticals-Vol. XXTX, No. 2 Syntherlr of Novel ... more Page 1. Journal of Labelled Compounds and Radiophamceuticals-Vol. XXTX, No. 2 Syntherlr of Novel Tritium labeled Oxamyrlrtlc Acids Balekudru Devadas,'a Steven P. Adams,. and Jeffrey 1. Gordonb a Monsanto Company, 700 Chesterfield Village Parkway, St. ...
Journal of Biological Chemistry, 1998
Cryptococcus neoformans is a fungal pathogen that causes chronic meningitis in 10% of patients wi... more Cryptococcus neoformans is a fungal pathogen that causes chronic meningitis in 10% of patients with AIDS. Genetic and biochemical studies were conducted to determine whether myristoyl-CoA:protein N-myristoyltransferase (Nmt) is a target for development of a new class of fungicidal drugs. A single copy of a conditional lethal C. neoformans NMT allele was introduced into the fungal genome by homologous recombination. The allele (nmt487D) produces temperature-sensitive myristic acid auxotrophy. This phenotype is due, in part, to under-myristoylation of a cellular ADP ribosylation factor (Arf) and can be rescued by forced expression of human Nmt. Two isogenic strains with identical growth kinetics at 35 degreesC were used to test the biological effects of an Nmt inhibitor. CPA8 contained a single copy of wild type C. neoformans NMT. HMC1 contained nmt487D plus 10 copies of human NMT. Since a single copy of nmt487D will not support growth at 35 degreesC, survival of HMC1 depends upon its human Nmt. ALYASKLS-NH2, an inhibitor derived from an Arf, was fully depeptidized: p-[(2-methyl-1-imidazol-1-yl)butyl]phenyl-acetyl was used to represent the GLYA tetrapeptide, whereas SKLS was replaced with a chiral tyrosinol scaffold. Kinetic studies revealed Ki (app) values of 1.8 +/- 1 and 9 +/- 2.4 microM for purified fungal and human Nmts, respectively. The minimal inhibitory concentration of the compound was 2-fold lower for CPA8 compared with HMC1. A single dose of 100 microM produced a 5-fold greater inhibition of protein synthesis in CPA8 versus HMC1. The strain specificity of these responses indicates that the fungicidal effect was Nmt-dependent. These two strains may be useful for screening chemical libraries for Nmt-based fungicidal compounds with relatively little activity against the human enzyme.
Journal of the American Chemical Society, 1990
Journal of the American Chemical Society, 1987
The Journal of Organic Chemistry, 1987
Synthetic Communications, 1995
ABSTRACT Syntheses of novel 3-ethynyl (8), 3-vinyl (10) and 3-acetoxy (13)-2′-deoxy-3-deazauridin... more ABSTRACT Syntheses of novel 3-ethynyl (8), 3-vinyl (10) and 3-acetoxy (13)-2′-deoxy-3-deazauridine analogs starting from the protected 2′-deoxy-3-deazauridine derivative 4 are described.
Journal of the American Chemical Society, 1986
The captodative free radical 3,5,5-trimethyl-2-oxomorpholin-3-yl (1, TM-3) from bond homolysis of... more The captodative free radical 3,5,5-trimethyl-2-oxomorpholin-3-yl (1, TM-3) from bond homolysis of meso-and dl-bi(3,5,5-
Tetrahedron Letters, 1993
ABSTRACT
The Journal of biological chemistry, Jan 15, 1992
Covalent attachment of myristic acid (C14:0) to the amino-terminal glycine residue of a variety o... more Covalent attachment of myristic acid (C14:0) to the amino-terminal glycine residue of a variety of eukaryotic cellular and viral proteins can have a profound influence on their biological properties. The enzyme that catalyzes this modification, myristoyl-CoA-protein N-myristoyltransferase (NMT), has been identified as a potential target for antiviral and antifungal therapy. Its reaction mechanism is ordered Bi Bi with myristoyl-CoA binding occurring before binding of peptide and CoA release preceding release of myristoylpeptide. Perturbations in the binding of its acyl-CoA substrate would therefore be expected to have an important influence on catalysis. We have synthesized 56 analogs of myristic acid (C14:0) to further characterize the acyl-CoA binding site of Saccharomyces cerevisiae NMT. The activity of fatty acid analogs was assessed using a coupled in vitro assay system that employed the reportedly nonspecific Pseudomonas acyl-CoA synthetase, purified S. cerevisiae NMT, and oct...
Journal of medicinal chemistry, Jan 12, 1998
A new class of biologically active nonpeptidic inhibitors of Candida albicans NMT has been synthe... more A new class of biologically active nonpeptidic inhibitors of Candida albicans NMT has been synthesized starting from the octapeptide ALYASKLS-NH2 (2). The synthetic strategy entailed the preparation of novel protected Ser-Lys mimics 9 and 12 from (S)- or (R)-3-iodotyrosine and then grafting key enzyme recognition elements in a stepwise manner. Like 2, compounds 16, 17, and 18 are competitive Candida NMT inhibitors that bind to the peptide recognition site of the enzyme. Moreover, 16-18 have an affinity comparable to that of 2 even though they are devoid of peptide bonds. In contrast to 2, these nonpeptidic inhibitors exhibit antifungal activity.
Proceedings of the National Academy of Sciences, 1990
Covalent attachment of myristic acid (C14:0) to the NH2-terminal glycine residue of a number of c... more Covalent attachment of myristic acid (C14:0) to the NH2-terminal glycine residue of a number of cellular, viral, and oncogene-encoded proteins is essential for full expression of their biological function. Substitution of oxygen for methylene groups in this fatty acid does not produce a significant change in chain length or stereochemistry but does result in a reduction in hydrophobicity. These heteroatom-containing analogs serve as alternative substrates for ammalian myristoyl-CoA:protein N-myristoyltransferase (EC 2.3.1.97) and offer the opportunity to explore structure/function relationships of Abbreviations: FA, fatty acid; NMT, myristoyl-CoA:protein N-myristoyltransferase; RaSV, Rasheed sarcoma virus; C/M, cytosolic to membrane.
Proceedings of the National Academy of Sciences, 1991
Covalent linkage of myristate (tetradecanoate; 14:0) to the NH2-terminal glycine residue of the h... more Covalent linkage of myristate (tetradecanoate; 14:0) to the NH2-terminal glycine residue of the human immunodeficiency virus 1 (HIV-1) 55-kDa gag polyprotein precursor (Pr55gag) is necessary for its proteolytic processing and viral assembly. We have shown recently that several analogs of myristate in which a methylene group is replaced by a single oxygen or sulfur atom are substrates for Saccharomyces cerevisiae and mammalian myristoyl-CoA:protein N-myristoyltransferase (EC 2.3.1.97; NMT) despite their reduced hydrophobicity. Some inhibit HIV-1 replication in acutely infected CD4+H9 cells without accompanying cellular toxicity. To examine the mechanism of their antiviral effects, we performed labeling studies with two analogs, 12-methoxydodecanoate (13-oxamyristate; 13-OxaMyr) and 5-octyloxypentanoate (6-oxamyristate; 6-OxaMyr), the former being much more effective than the latter in blocking virus production. [3H]Myristate and [3H]13-OxaMyr were incorporated into Pr55gag with comparable efficiency when it was coexpressed with S. cerevisiae NMT in Escherichia coli. [3H]6-OxaMyr was not incorporated, even though its substrate properties in vitro were similar to those of 13-OxaMyr and myristate. [3H]13-OxaMyr, but not [3H]6-OxaMyr, was also efficiently incorporated into HIV-1 Pr55gag and nef (negative factor) in chronically infected H9 cells. Analog incorporation produced a redistribution of Pr55gag from membrane to cytosolic fractions and markedly decreased its proteolytic processing by viral protease. 13-OxaMyr and 3'-azido-3'-deoxythymidine (AZT) act synergistically to reduce virus production in acutely infected H9 cells. Unlike AZT, the analog is able to inhibit virus production (up to 70%) in chronically infected H9 cells. Moreover, the inhibitory effect lasts 6-8 days. These results suggest that (i) its mechanism of action is distinct from that of AZT and involves a late step in virus assembly; (ii) the analog may allow reduction in the dose of AZT required to affect viral replication; and (iii) combinations of analog and HIV-1 protease inhibitors may have synergistic effects on the processing of Pr55gag.
Microbiology, 1997
Myristoyl-CoA: protein N-myristoyltransf erase (Nmt) catalyses the covalent attachment of myrista... more Myristoyl-CoA: protein N-myristoyltransf erase (Nmt) catalyses the covalent attachment of myristate to the N-terminal glycine of a small subset of cellular proteins produced during vegetative growth of Candida albicans. nmt447D is a mutant NMT allele encoding an enzyme with a G l F 7 4 Asp substitution and reduced affinity for myristoyl-CoA. Among isogenic NMTINMT, NMTlhnmt and nmthlnmt447D strains, only nmthlnmt447D cells require myristate for growth on yeast/peptone/dextrose media (YPD) at 24 or 37 "C. When switched from YPD/myristate to YPD alone, 60% of the organisms die within 4 h.
The Journal of Organic Chemistry, 1991
... Tianbao Lu,* B. Devadas,l Steven P. Adams,* Jeffrey I. Gordon,+ and George W. Gokel*J Departm... more ... Tianbao Lu,* B. Devadas,l Steven P. Adams,* Jeffrey I. Gordon,+ and George W. Gokel*J Department of Chemistry, Uniuersity of Miami, Coral Gables, Florida 33124, Departments of Medicine and Biochemistry and Molecular Biophysics, Washington ... L. Zzu. (18) Kotva, R.; Cerny ...
Journal of Medicinal Chemistry, 1995
Design and Syntheses of Potent and Selective Dipeptide Inhibitors of Candida albicans Myristoyl-C... more Design and Syntheses of Potent and Selective Dipeptide Inhibitors of Candida albicans Myristoyl-CoAProtein N-Myris t oyltransferase ... Balekudru Devadas,* Mark E. Zupec, Sandra K. Freeman,' David L. Brown, Srinivasan Nagarajan, James A. Sikorski, Charles A. ...
Journal of Medicinal Chemistry, 1997
A new class of antifungal agents has been discovered which exert their activity by blockade of my... more A new class of antifungal agents has been discovered which exert their activity by blockade of myristoylCoA: protein N-myristoyltransferase (NMT; EC 2.1.3.97). Genetic experiments have established that NMT is needed to maintain the viability of Candida albicans and Cryptococcus neoformans,the two principal causes of systemic fungal infections in immunocompromised humans. Beginning with a weak octapeptide inhibitor ALYASKLS-NH2 (2, Ki = 15.3 +/- 6.4 microM), a series of imidazole-substituted Ser-Lys dipeptide amides have been designed and synthesized as potent and selective inhibitors of Candida albicans NMT. The strategy that led to these inhibitors evolved from the identification of those functional groups in the high-affinity octapeptide substrate GLYASKLS-NH2 1a necessary for tight binding, truncation of the C-terminus, replacement of the four amino acids at the N-terminus by a spacer group, and substitution of the glycine amino group with an N-linked 2-methylimidazole moiety. Initial structure-activity studies led to the identification of 31 as a potent and selective peptidomimetic inhibitor with an IC50 of 56 nM and 250-fold selectivity versus human NMT. 2-Methylimidazole as the N-terminal amine replacement in combination with a 4-substituted phenacetyl moiety imparts remarkable potency and selectivity to this novel class of inhibitors. The (S,S) stereochemistry of serine and lysine residues is critical for the inhibitory activity, since the (R,R) enantiomer 40 is 10(3)-fold less active than the (S,S) isomer 31. The inhibitory profile exhibited by this new class of NMT ligands is a function of the pKa of the imidazole substituent as illustrated by the benzimidazole analog 35 which is about 10-fold less potent than 31. The measured pKa (7.1 +/- 0.5) of 2-methylimidazole in 31 is comparable with the estimated pKa (approximately 8.0) of the glycyl residue in the high-affinity substrate 1a. Groups bulkier than methyl, such as ethyl, isopropyl, or iodo, at the imidazole 2-position have a detrimental effect on potency. Further refinement of 31 by grafting an alpha-methyl group at the benzylic position adjacent to the serine residue led to 61 with an IC50 of 40 nM. Subsequent chiral chromatography of 61 culminated in the discovery of the most potent Candida NMT inhibitor 61a reported to date with an IC50 of 20 nM and 400-fold selectivity versus the human enzyme. Both 31 and 61a are competitive inhibitors of Candida NMT with respect to the octapeptide substrate GNAASARR-NH2 with Ki(app) = 30 and 27 nM, respectively. The potency and selectivity displayed by these inhibitors are dependent upon the size and orientation of the alpha-substituent. An alpha-methyl group with the R configuration corresponding to the (S)-methyl-4-alanine in 2 confers maximum potency and selectivity. Structural modification of 31 and 61 by appending an (S)-carboxyl group beta to the cyclohexyl moiety provided the less potent tripeptide inhibitors 73a and 73b with an IC50 of 1.45 +/- 0.08 and 0.38 +/- 0.03 microM, respectively. However, these tripeptides (73a and 73b) exhibited a pronounced selectivity of 560- and 2200-fold versus the human NMT. More importantly 73a displayed fungistatic activity against C albicans with an EC50 of 51 +/- 17 microM in cell culture. Compound 73b also exhibited a similar antifungal activity. An Arf protein gel mobility shift assay for monitoring intracellular myristoylation revealed that a single dose of 200 microM of 73a or 73b produced < 50% reduction in Arf N-myristoylation, after 24 and 48 h, consistent with their fungistatic rather than fungicidal activity. In contrast, the enantiomer 73d which had an IC50 > 1000 microM against C. albicans NMT did not exhibit antifungal activity and produced no detectable reduction in Arf N-myristoylation in cultures of C. albicans. These studies confirm that the observed antifungal activity of 73a and 73b is due to the attenuation of NMT activity and that NMT represents an attractive tar
Journal of Medicinal Chemistry, 1997
MyristoylCoA:protein N-myristoyltransferase (NMT) covalently attaches the 14-carbon saturated fat... more MyristoylCoA:protein N-myristoyltransferase (NMT) covalently attaches the 14-carbon saturated fatty acid myristate, via an amide bond, to the N-terminal glycine residues of a variety of cellular proteins. Genetic studies have shown that NMT is essential for the viability of the principal ...
Journal of Labelled Compounds and Radiopharmaceuticals, 1991
Page 1. Journal of Labelled Compounds and Radiophamceuticals-Vol. XXTX, No. 2 Syntherlr of Novel ... more Page 1. Journal of Labelled Compounds and Radiophamceuticals-Vol. XXTX, No. 2 Syntherlr of Novel Tritium labeled Oxamyrlrtlc Acids Balekudru Devadas,'a Steven P. Adams,. and Jeffrey 1. Gordonb a Monsanto Company, 700 Chesterfield Village Parkway, St. ...
Journal of Biological Chemistry, 1998
Cryptococcus neoformans is a fungal pathogen that causes chronic meningitis in 10% of patients wi... more Cryptococcus neoformans is a fungal pathogen that causes chronic meningitis in 10% of patients with AIDS. Genetic and biochemical studies were conducted to determine whether myristoyl-CoA:protein N-myristoyltransferase (Nmt) is a target for development of a new class of fungicidal drugs. A single copy of a conditional lethal C. neoformans NMT allele was introduced into the fungal genome by homologous recombination. The allele (nmt487D) produces temperature-sensitive myristic acid auxotrophy. This phenotype is due, in part, to under-myristoylation of a cellular ADP ribosylation factor (Arf) and can be rescued by forced expression of human Nmt. Two isogenic strains with identical growth kinetics at 35 degreesC were used to test the biological effects of an Nmt inhibitor. CPA8 contained a single copy of wild type C. neoformans NMT. HMC1 contained nmt487D plus 10 copies of human NMT. Since a single copy of nmt487D will not support growth at 35 degreesC, survival of HMC1 depends upon its human Nmt. ALYASKLS-NH2, an inhibitor derived from an Arf, was fully depeptidized: p-[(2-methyl-1-imidazol-1-yl)butyl]phenyl-acetyl was used to represent the GLYA tetrapeptide, whereas SKLS was replaced with a chiral tyrosinol scaffold. Kinetic studies revealed Ki (app) values of 1.8 +/- 1 and 9 +/- 2.4 microM for purified fungal and human Nmts, respectively. The minimal inhibitory concentration of the compound was 2-fold lower for CPA8 compared with HMC1. A single dose of 100 microM produced a 5-fold greater inhibition of protein synthesis in CPA8 versus HMC1. The strain specificity of these responses indicates that the fungicidal effect was Nmt-dependent. These two strains may be useful for screening chemical libraries for Nmt-based fungicidal compounds with relatively little activity against the human enzyme.