Human Leukotriene A4 Hydrolase Research Articles

Design of benzimidazoles, benzoxazoles, benzothiazoles and thiazolopyridines as leukotriene A4 hydrolase inhibitors through 3D-QSAR, docking and molecular dynamics

Human leukotriene A4 hydrolase enzyme (LTA4H) catalyses the biotransformation of the inactive precursor leukotriene A4 (LTA4) to the bioactive Leukotriene B4 (LTB4), which causes many inflammatory responses in the human body. Therefore, the selective inhibition of this enzyme becomes a useful strategy for the treatment of several illnesses such as asthma, allergic rhinitis, cardiovascular diseases, and cancer. Herein we report a 3D-QSAR/ /CoMFA and CoMSIA study on a series of 47 benzimidazoles, benzoxazoles, benzothiazoles and thiazolopyridines reported as potent LTA4H inhibitors. Good statistical parameters were obtained for the best model (q2 = 0.568, r2 ncv = 0.891 and r2 test = 0.851). A new series of 10 compounds capable of inhibiting leukotriene A4 hydrolase with high potency was presented. All designed inhibitors showed low IC50 in nano- and sub-nanomolar ranges, when they were evaluated in 3D-QSAR models. Subsequently, the designed molecules, as well as the least and most active compounds were subjected to docking and molecular dynamics studies into LTA4H. In conclusion, we summarised a thorough structure?activity relationship (SAR) of LTA4H inhibitors of heterocyclic structure. These models can be used for the rational proposal of new inhibitors.

In Silico Study of Anticancer Activity of Red Betel Leaves Bioactive Compounds against Colon Cancer Marker Proteins

Colon cancer or colorectal cancer is one of the major health problems in the world. Previous research has proven that red betel leaves extract has anticancer activity against breast cancer cells. The study aimed to look at the potential of compounds contained in red betel ethyl acetate fraction as anticancer substances for colon cancer by conducting in silico tests through the docking of three colon cancer biomarker receptors against eight red betel leaves compounds. The parameters of binding affinity energy and inhibition constant used in the molecular docking analysis showed that there are several compounds that have the potential as inhibitors against colon cancer marker proteins to inhibit the development of colorectal cancer and have high bioavalibility as oral drugs. Based on in silico test it is known that the compound N-1,N-9-Bis [E-(2-nitophenyl) methylene] non anedihydrazide has the highest inhibition of human leukotriene A4 hydrolase receptor with binding affinity energy of 11.3160 Kcal/mol. The next compound is 4-({4,6-Bis[3R,5S)-3,5-diamino-1-piperydinyl]-1,3,5-traizin-2-yl}amino) benzenosulfon amide which has the highest inhibition in Chek1 with binding affinity energy of 9.7110 Kcal/mol, and the compound 4-(4-methoxy-phenylamino)-2,3-dihydro-1H-4a, 9-diaza-cyclopenta (b) fluorine-10-carbonitrile has the highest inhibition in the Bcl 2 navitoclax analog receptor with binding affinity energy of 8.4470 Kcal/mol.

Relationship between human LTA4H polymorphisms and extra-pulmonary tuberculosis in an ethnic Han Chinese population in Eastern China

Two single nucleotide polymorphisms in Leukotriene A4 hydrolase (LTA4H) gene were reported to be associated with protection from pulmonary tuberculosis in Vietnamese population. But these associations were not found in the Russians. To investigate the association of LTA4H polymorphisms with tuberculosis in a Han Chinese population in Eastern China, we genotyped 5 SNPs of LTA4H gene in 743 of pulmonary tuberculosis patients, 372 of extra-pulmonary tuberculosis patients and 888 of healthy controls individuals. The CC and TT homozygotes of rs1978331 and rs2540474 were identified to have higher rates (P < 0.01) and be risk factors in the patients with extra-pulmonary tuberculosis (OR = 1.412; 95% CI = 1.104-1.804 and(OR = 1.380; 95% CI = 1.080-1.764). However, no significant association was found between any of the SNPs and pulmonary tuberculosis. In the extra-pulmonary tuberculosis subgroups. LTA4H gene were significantly associated with tuberculous meningitis, lymph node tuberculosis, bone tuberculosis and other extra-pulmonary tuberculosis except for pleural tuberculosis. The present findings suggest that polymorphisms in the LTA4H gene may affect susceptibility to extra-pulmonary tuberculosis and change the risk of developing the disease in the Han nationality in the East China.

A remarkable activity of human leukotriene A4 hydrolase (LTA4H) toward unnatural amino acids

Leukotriene A4 hydrolase (LTA4H––EC 3.3.2.6) is a bifunctional zinc metalloenzyme, which processes LTA4 through an epoxide hydrolase activity and is also able to trim one amino acid at a time from N-terminal peptidic substrates via its aminopeptidase activity. In this report, we have utilized a library of 130 individual proteinogenic and unnatural amino acid fluorogenic substrates to determine the aminopeptidase specificity of this enzyme. We have found that the best proteinogenic amino acid recognized by LTA4H is arginine. However, we have also observed several unnatural amino acids, which were significantly better in terms of cleavage rate (k cat/K m values). Among them, the benzyl ester of aspartic acid exhibited a k cat/K m value that was more than two orders of magnitude higher (1.75 × 105 M−1 s−1) as compared to l-Arg (1.5 × 103 M−1 s−1). This information can be used for design of potent inhibitors of this enzyme, but may also suggest yet undiscovered functions or specificities of LTA4H.Electronic supplementary materialThe online version of this article (doi:10.1007/s00726-014-1694-2) contains supplementary material, which is available to authorized users.

The novel 13S,14S‐epoxy‐maresin is converted by human macrophages to maresin 1 (MaR1), inhibits leukotriene A4hydrolase (LTA4H), and shifts macrophage phenotype

Maresins are produced by macrophages from docosahexaenoic acid (DHA) and exert potent proresolving and tissue homeostatic actions. Maresin 1 (MaR1; 7R,14S-dihydroxy-docosa-4Z,8E,10E,12Z,16Z,19Z-hexaenoic acid) is the first identified maresin. Here, we investigate formation, stereochemistry, and precursor role of 13,14-epoxy-docosahexaenoic acid, an intermediate in MaR1 biosynthesis. The 14-lipoxygenation of DHA by human macrophage 12-lipoxygenase (hm12-LOX) gave 14-hydro(peroxy)-docosahexaenoic acid (14-HpDHA), as well as several dihydroxy-docosahexaenoic acids, implicating an epoxide intermediate formation by this enzyme. Using a stereo-controlled synthesis, enantiomerically pure 13S,14S-epoxy-docosa-4Z,7Z,9E,11E,16Z,19Z-hexaenoic acid (13S,14S-epoxy-DHA) was prepared, and its stereochemistry was confirmed by NMR spectroscopy. When this 13S,14S-epoxide was incubated with human macrophages, it was converted to MaR1. The synthetic 13S,14S-epoxide inhibited leukotriene B4 (LTB4) formation by human leukotriene A4 hydrolase (LTA4H) ∼40% (P<0.05) to a similar extent as LTA4 (∼50%, P<0.05) but was not converted to MaR1 by this enzyme. 13S,14S-epoxy-DHA also reduced (∼60%; P<0.05) arachidonic acid conversion by hm12-LOX and promoted conversion of M1 macrophages to M2 phenotype, which produced more MaR1 from the epoxide than M1. Together, these findings establish the biosynthesis of the 13S,14S-epoxide, its absolute stereochemistry, its precursor role in MaR1 biosynthesis, and its own intrinsic bioactivity. Given its actions and role in MaR1 biosynthesis, this epoxide is now termed 13,14-epoxy-maresin (13,14-eMaR) and exhibits new mechanisms in resolution of inflammation in its ability to inhibit proinflammatory mediator production by LTA4 hydrolase and to block arachidonate conversion by human 12-LOX rather than merely terminating phagocyte involvement.

Development of Predictive Quantitative Structure–Activity Relationship Model and Its Application in the Discovery of Human Leukotriene A4 Hydrolase Inhibitors

Human LTA4H catalyzes the conversion of LTA4 to LTB4 and plays a key role in innate immune responses. Inhibition of this enzyme can be a valid method in the treatment of inflammatory response exhibited through LTB4. The quantitative structure-activity relationship (QSAR) models were developed using genetic function approximation and validated. A training set of 26 diverse compounds and their molecular descriptors were used to develop highly correlating QSAR models. A six-descriptor model explaining the biological activity of the training and test sets with correlation values of 0.846 and 0.502, respectively, was selected as the best model and used in a database screening of drug-like Maybridge database followed by molecular docking. Based on the predicted potent inhibitory activities, expected binding mode and molecular interactions at the active site of hLTA4H final leads were selected as to be utilized in designing future hLTA4H inhibitors.

Optimization of 5-hydroxytryptamines as dual function inhibitors targeting phospholipase A2 and leukotriene A4 hydrolase

Dual function inhibitors targeting phospholipase A2 (PLA2) and leukotriene A4 hydrolase (LTA4H) may balance the arachidonic acid (AA) metabolic network and be used as new anti-inflammatory drugs. In previous study, we discovered multi-target drugs towards the AA metabolic network, among which a dual-target inhibitor (JMC08-4) for human nonpancreatic secretory phospholipase A2 (hnps-PLA2) and human leukotriene A4 hydrolase (LTA4H-h) was found. Based on the structure of compound JMC08-4, new dual-target inhibitors were designed assisted by molecular docking. In this report, a series of 5-hydroxytryptamine compounds were synthesized; and most of these title compounds showed more potent inhibitory activity than compound JMC08-4 in the in vitro bioassay against these two enzymes. The best one inhibited hnps-PLA2 and LTA4H-h with IC50 values of 9.2 ± 0.5 μM and 2.4 ± 1.4 μM, respectively.

Structural Origins for the Loss of Catalytic Activities of Bifunctional Human LTA4H Revealed through Molecular Dynamics Simulations

Human leukotriene A4 hydrolase (hLTA4H), which is the final and rate-limiting enzyme of arachidonic acid pathway, converts the unstable epoxide LTA4 to a proinflammatory lipid mediator LTB4 through its hydrolase function. The LTA4H is a bi-functional enzyme that also exhibits aminopeptidase activity with a preference over arginyl tripeptides. Various mutations including E271Q, R563A, and K565A have completely or partially abolished both the functions of this enzyme. The crystal structures with these mutations have not shown any structural changes to address the loss of functions. Molecular dynamics simulations of LTA4 and tripeptide complex structures with functional mutations were performed to investigate the structural and conformation changes that scripts the observed differences in catalytic functions. The observed protein-ligand hydrogen bonds and distances between the important catalytic components have correlated well with the experimental results. This study also confirms based on the structural observation that E271 is very important for both the functions as it holds the catalytic metal ion at its location for the catalysis and it also acts as N-terminal recognition residue during peptide binding. The comparison of binding modes of substrates revealed the structural changes explaining the importance of R563 and K565 residues and the required alignment of substrate at the active site. The results of this study provide valuable information to be utilized in designing potent hLTA4H inhibitors as anti-inflammatory agents.

Molecular Dynamics Simulation Study and Hybrid Pharmacophore Model Development in Human LTA4H Inhibitor Design

Human leukotriene A4 hydrolase (hLTA4H) is a bi-functional enzyme catalyzes the hydrolase and aminopeptidase functions upon the fatty acid and peptide substrates, respectively, utilizing the same but overlapping binding site. Particularly the hydrolase function of this enzyme catalyzes the rate-limiting step of the leukotriene (LT) cascade that converts the LTA4 to LTB4. This product is a potent pro-inflammatory activator of inflammatory responses and thus blocking this conversion provides a valuable means to design anti-inflammatory agents. Four structurally very similar chemical compounds with highly different inhibitory profile towards the hydrolase function of hLTA4H were selected from the literature. Molecular dynamics (MD) simulations of the complexes of hLTA4H with these inhibitors were performed and the results have provided valuable information explaining the reasons for the differences in their biological activities. Binding mode analysis revealed that the additional thiophene moiety of most active inhibitor helps the pyrrolidine moiety to interact the most important R563 and K565 residues. The hLTA4H complexes with the most active compound and substrate were utilized in the development of hybrid pharmacophore models. These developed pharmacophore models were used in screening chemical databases in order to identify lead candidates to design potent hLTA4H inhibitors. Final evaluation based on molecular docking and electronic parameters has identified three compounds of diverse chemical scaffolds as potential leads to be used in novel and potent hLTA4H inhibitor design.

Pharmacophore-based virtual screening and Bayesian model for the identification of potential human leukotriene A4 hydrolase inhibitors

Leukotriene A4 hydrolase (LTA4H), an enzyme involved in the conversion of LTA4 to LTB4, is an emerging and important anti-inflammatory target. This study demonstrates the development of quantitative pharmacophore hypothesis and Bayesian model and their applications in identification of potential human LTA4H (hLTA4H) inhibitors. The best hypothesis with a high correlation coefficient value of 0.951 was validated using different methods including a test set containing 136 compounds. It was further used as a three-dimensional query in database searching to retrieve virtual leads for hLTA4H inhibition. Molecular docking study was employed to identify the compounds that bind the active site with high affinity. Developed Bayesian model suggested molecular features favoring and not favoring the inhibition of hLTA4H.

Discovery of Multitarget Inhibitors by Combining Molecular Docking with Common Pharmacophore Matching

Multitarget drugs have been to be found effective in controlling complex diseases. However, how to design multitarget drugs presents a great challenge. We have developed a computer-assisted strategy to screen for multitarget inhibitors using a combination of molecular docking and common pharmacophore matching. This strategy was successfully applied to screen for dual-target inhibitors against both the human leukotriene A(4) hydrolase (LTA4H-h) and the human nonpancreatic secretory phospholipase A2 (hnps-PLA2). Three compounds screened from the chemical database MDL Available Chemical Directory were found to inhibit these two enzymes at the 10 microM level. Moreover, one synthetic compound matching the common pharmacophores inhibits LTA4H-h and hnps-PLA2 with IC(50) values of 35 nM and 7.3 microM, respectively. The common pharmacophore model can also be used to search small molecule databases or collections of existing inhibitors, as well as to guide combinatorial library design to search for ideal multitarget inhibitors.

Leukotriene A4 Hydrolase, Insights into the Molecular Evolution by Homology Modeling and Mutational Analysis of Enzyme from Saccharomyces cerevisiae

Mammalian leukotriene A4 (LTA4) hydrolase is a bifunctional zinc metalloenzyme possessing an Arg/Ala aminopeptidase and an epoxide hydrolase activity, which converts LTA4 into the chemoattractant LTB4. We have previously cloned an LTA4 hydrolase from Saccharomyces cerevisiae with a primitive epoxide hydrolase activity and a Leu aminopeptidase activity, which is stimulated by LTA4. Here we used a modeled structure of S. cerevisiae LTA4 hydrolase, mutational analysis, and binding studies to show that Glu-316 and Arg-627 are critical for catalysis, allowing us to a propose a mechanism for the epoxide hydrolase activity. Guided by the structure, we engineered S. cerevisiae LTA4 hydrolase to attain catalytic properties resembling those of human LTA4 hydrolase. Thus, six consecutive point mutations gradually introduced a novel Arg aminopeptidase activity and caused the specific Ala and Pro aminopeptidase activities to increase 24 and 63 times, respectively. In contrast to the wild type enzyme, the hexuple mutant was inhibited by LTA4 for all tested substrates and to the same extent as for the human enzyme. In addition, these mutations improved binding of LTA4 and increased the relative formation of LTB4, whereas the turnover of this substrate was only weakly affected. Our results suggest that during evolution, the active site of an ancestral eukaryotic zinc aminopeptidase has been reshaped to accommodate lipid substrates while using already existing catalytic residues for a novel, gradually evolving, epoxide hydrolase activity. Moreover, the unique ability to catalyze LTB4 synthesis appears to be the result of multiple and subtle structural rearrangements at the catalytic center rather than a limited set of specific amino acid substitutions.

Crystallization and X-ray diffraction data analysis of leukotriene A4 hydrolase from Saccharomyces cerevisiae.

The Saccharomyces cerevisiae leukotriene A4 (LTA4) hydrolase (scLTA4 hydrolase) has been crystallized in order to study the two activities of LTA4 hydrolase in an evolutionary perspective. Single well diffracting crystals are obtained after switching from the hanging-drop method to liquid-liquid diffusion in capillaries using PEG 8000 as precipitant. These crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 70.8, b = 98.1, c = 99.2 A. Intensity data to 2.3 A resolution were collected from a native scLTA4 hydrolase crystal using synchrotron radiation. A molecular-replacement solution was obtained using the human LTA4 hydrolase structure and the program BEAST.

Studies of Lipoxygenases in the Epithelium of Cultured Bovine Cornea Using an Air Interface Model

Epithelial lipoxygenases of bovine cornea were investigated in organ culture models. Subcellular fractions of the epithelium were incubated with14C-labelled arachidonate and the metabolites were analysed. Bovine corneal epithelial cells contain 15-lipoxygenase type 2 and 12-lipoxygenases of the leukocyte and the platelet types. The 15-lipoxygenase activity was prominent in the cytosolic fraction. Twelve- and 15-lipoxygenases occurred in the microsomal fraction, where the 15-lipoxygenase activity appeared to be favoured by low protein levels. The lipoxygenase activities strongly declined within 24hr when the cornea was covered with cell culture medium, but were maintained with high activity in an air interface organ culture model for at least 72hr. Cultured corneas were studied in pairs in the air interface model under influence of inflammatory stimuli. The epithelial 15- and 12-lipoxygenase activities were only slightly augmented by treatment with 12- O -tetradecanoyl-phorbol-13-acetate (10μM, 8–72hr), and remained unchanged after treatment with lipopolysaccharide (1–100μ g ml−1, 8–72hr) or UV irradiation (301nm, 0.17J cm−2; 8–24hr). In some experiments, 5-lipoxygenase activity was detectable, as judged from liquid chromatography-mass spectrometry and chiral chromatography. Reverse transcription-polymerase chain reaction and Northern blot analysis were therefore used to identify mRNA of 5-lipoxygenase and related enzymes in bovine epithelium. 5-Lipoxygenase was detected as an amplicon of 695bp, which had 91% nucleotide sequence identity with human 5-lipoxygenase and by Northern blot as a 3.0kb mRNA. Leukotriene A4hydrolase was detected with the same techniques. The amino acid sequence of a 612bp fragment was 90% identical with human leukotriene A4hydrolase and the size of the mRNA was 2.7kb. The two enzymes were also detected in human corneal epithelium by reverse transcription-polymerase chain reaction.

The sequence of 12.8 kb from the left arm of chromosome XIV reveals a sigma element, a pro-tRNA and six complete open reading frames, one of which encodes a protein similar to the human leukotriene A4 hydrolase.

We have determined the nucleotide sequence of a 12.8 kb fragment from the left arm of chromosome XIV carried by the cosmid 14-16d. An analysis of the sequence reveals the presence of a sigma element, a pro-tRNA gene and eight open reading frames, six of which are complete. All of the eight open reading frames correspond to new genes. Of the eight new genes, two show strong similarities to a pair of new genes from chromosome IX, suggesting an ancestral duplication, and one gene encodes a protein similar to mammalian leukotriene A4 hydrolase.

Molecular Cloning and Functional Expression of aCaenorhabditis elegans Aminopeptidase Structurally Related to Mammalian Leukotriene A4 Hydrolases

In a search of the Caenorhabditis elegans DNA data base, an expressed sequence tag of 327 base pairs (termed cm01c7) with strong homology to the human leukotriene A4 (LTA4) hydrolase was found. The use of cm01c7 as a probe, together with conventional hybridization screening and anchored polymerase chain reaction techniques resulted in the cloning of the full-length 2.1 kilobase pair C. elegans LTA4 hydrolase-like homologue, termed aminopeptidase-1 (AP-1). The AP-1 cDNA was expressed transiently as an epitope-tagged recombinant protein in COS-7 mammalian cells, purified using an anti-epitope antibody affinity resin, and tested for LTA4 hydrolase and aminopeptidase activities. Despite the strong homology between the human LTA4 hydrolase and C. elegans AP-1(63% similarity and 45% identity at the amino acid level), reverse-phase high pressure liquid chromatography and radioimmunoassay for LTB4 production revealed the inability of the C. elegans AP-1 to use LTA4 as a substrate. In contrast, the C. elegans AP-1 was an efficient aminopeptidase, as demonstrated by its ability to hydrolyze a variety of amino acid p-nitroanilide derivatives. The aminopeptidase activity of C. elegans AP-1 resembled that of the human LTA4 hydrolase/aminopeptidase enzyme with a preference for arginyl-p-nitroanilide as a substrate. Hydrolysis of the amide bond of arginyl-p-nitroanilide was inhibited by bestatin with an IC50 of 2.6 +/- 1.2 microM. The bifunctionality of the mammalian LTA4 hydrolase is still poorly understood, as the physiological substrate for its aminopeptidase activity is yet to be discovered. Our results support the idea that the enzyme originally functioned as an aminopeptidase in lower metazoa and then developed LTA4 hydrolase activity in more evolved organisms.

Detection of both active and inactive human leukotriene A4 hydrolase by isoelectric gelelectrophoresis

Detection of both active and inactive human leukotriene A4 hydrolase by isoelectric gelelectrophoresis

Leukotriene A4 hydrolase: protection from mechanism-based inactivation by mutation of tyrosine-378.

Leukotriene A4 (LTA4) hydrolase [(7E,9E,11Z,14Z)-(5S,6S)-5,6-epoxyicosa-7, 9,11,14-tetraenoate hydrolase; EC 3.3.2.6] is a bifunctional zinc metalloenzyme that catalyzes the final step in the biosynthesis of the potent chemotactic agent leukotriene B4 (LTB4). LTA4 hydrolase/aminopeptidase is suicide inactivated during catalysis via an apparently mechanism-based irreversible binding of LTA4 to the protein in a 1:1 stoichiometry. Previously, we have identified a henicosapeptide, encompassing residues Leu-365 to Lys-385 in human LTA4 hydrolase, which contains a site involved in the covalent binding of LTA4 to the native enzyme. To investigate the role of Tyr-378, a potential candidate for this binding site, we exchanged Tyr for Phe or Gln in two separate mutants. In addition, each of two adjacent and potentially reactive residues, Ser-379 and Ser-380, were exchanged for Ala. The mutated enzymes were expressed as (His)6-tagged fusion proteins in Escherichia coli, purified to apparent homogeneity, and characterized. Enzyme activity determinations and differential peptide mapping, before and after repeated exposure to LTA4, revealed that wild-type enzyme and the mutants [S379A] and [S380A]LTA4hydrolase were equally susceptible to suicide inactivation whereas the mutants in position 378 were no longer inactivated or covalently modified by LTA4. Furthermore, in [Y378F]LTA4 hydrolase, the value of kcat for epoxide hydrolysis was increased 2.5-fold over that of the wild-type enzyme. Thus, by a single-point mutation in LTA4 hydrolase, catalysis and covalent modification/inactivation have been dissociated, yielding an enzyme with increased turnover and resistance to mechanism-based inactivation.

Formation of a novel enzymatic metabolite of leukotriene A4 in tissues of Xenopus laevis.

Leukotriene-A4, hydrolase catalyzes the final step in the biosynthesis of the potent proinflammatory mediator leukotriene B4. Previously, leukotriene-A4 hydrolase has been characterized from human, mouse and rat sources, i.e. only from mammalian species. In the present investigation, expression of leukotriene-A4, hydrolase was studied in organs of Xenopus laevis. Enzyme activity was found in all nine organs tested with the highest levels in the intestine and the reproductive organs, i.e. oocytes and testes, previously unrecognized rich sources of the enzyme. No immunoreactive leukotriene-A4 hydrolase was detected in Western blots of 10000Xg supernatants of X. laevis organ homogenates, using a polyclonal antiserum raised against human leukotriene-A4 hydrolase. Likewise, Northern blot analysis of liver total RNA did not detect Xenopus leukotriene-A4 hydrolase mRNA using a human CDNA probe. These results indicate significant structural differences between the human and toad enzymes. Incubations of 10000Xg supernatants of organ homogenates with leukotriene A4 revealed the formation of a novel metabolite, denoted compound X. Conversion of leukotriene A4 into compound X was due to an enzymatic activity as judged by its protein dependence, heat sensitivity, and resistance to ultrafiltration, and this activity appeared to be linked, directly or indirectly,, to leukotriene A4 hydrolase. From data obtained by ultraviolet spectrophotometry, gas chromatography coupled to mass spectrometry, ultraviolet-induced isomerization, and comparison with a synthetic standard, compound X was assigned the structure 5S,12R-dihydroxy-6,10-trans-8,14-cis-eicosatetraenoic acid. Finally, compound X was found to exhibit contractile activity in guinea-pig lung parenchyma, apparently elicited via a leukotriene B receptor.

The Sequence of 12·8 kb from the Left Arm of Chromosome XIV Reveals a Sigma Element, a pro‐tRNA and Six Complete Open Reading Frames, One of Which Encodes a Protein Similar to the Human Leukotriene A4 Hydrolase

We have determined the nucleotide sequence of a 12·8 kb fragment from the left arm of chromosome XIV carried by the cosmid 14-16d. An analysis of the sequence reveals the presence of a sigma element, a pro-tRNA gene and eight open reading frames, six of which are complete. All of the eight open reading frames correspond to new genes. Of the eight new genes, two show strong similarities to a pair of new genes from chromosome IX, suggesting an ancestral duplication, and one gene encodes a protein similar to mammalian leukotriene A4 hydrolase. The sequence has been deposited in the EMBL data bank under the Accession Number X94547.