Disease relevance of NORLEUCINE

• The X-ray crystal structures of an anti-p24 (HIV-1) monoclonal antibody Fab fragment alone and in complexes with the epitope peptide GATPQDLNTnL (n = norleucine), an epitope-homologous peptide GATPEDLNQKLAGN, as well as two unrelated peptides GLYEWGGARITNTD and efslkGpllqwrsG (D-peptide), are presented to a maximum resolution of 2.6 A [1].
• The structure of a complex between a peptide inhibitor with the sequence N-acetyl-Thr-Ile-Nle-psi[CH2-NH]-Nle-Gln-Arg.amide (Nle, norleucine) with chemically synthesized HIV-1 (human immunodeficiency virus 1) protease was determined at 2.3 A resolution (R factor of 0.176) [2].
• Biosynthesis of a protein containing a nonprotein amino acid by Escherichia coli: L-2-aminohexanoic acid at position 21 in human epidermal growth factor [3].
• This was also true for the D and L forms of the non-utilisable isomer of Leu, norleucine (nLeu) [4].
• Norleucine accumulation by a norleucine-resistant mutant of Serratia marcescens [5].

High impact information on NORLEUCINE

• The antibody active site also contains a Lys residue to stabilize oxyanion formation, and a hydrophobic binding pocket for specific substrate recognition of norleucine and methionine side chains [6].
• Corticotropin-releasing factor (CRF) receptors were identified in rat forebrain by autoradiography with an iodine-125-labeled analog of ovine CRF substituted with norleucine and tyrosine at amino acid residues 21 and 32, respectively [7].
• All antagonistic analogs had the common core sequence [PhAc-Tyr1,D-Arg2, Phe(4-Cl)6 (para-chlorophenylalanine), Abu15 (alpha-aminobutyric acid), Nle27]hGH-RH(1-29)NH2 and contained Arg, D-Arg, homoarginine (Har), norleucine (Nle), and other substitutions [8].
• Analogs of the 29 amino acid sequence of human growth hormone-releasing hormone (hGH-RH) with agmatine (Agm) in position 29, desaminotyrosine (Dat) in position 1, norleucine (Nle) in position 27, and L-alpha-aminobutyric acid (Abu) in position 15 have been synthesized, and their biological activity was evaluated [9].
• (i) Antagonist analogs of the form -Leu26-psi(CH2NH)-Xaa27-NH2 [where Xaa is Leu, norleucine (Nle), or Phe; residues numbered after GRP], similar to those introduced by Coy and coworkers [for review, see Jensen, R. T. & Coy, D. H. (1991) Trends Pharmacol. Sci. 12, 13-19], were found to have nanomolar potencies [10].

Chemical compound and disease context of NORLEUCINE

• Incorporation of norleucine at methionine positions in recombinant human macrophage colony stimulating factor (M-CSF, 4-153) expressed in Escherichia coli: structural analysis [11].
• To understand the processing of the CA-p2 site, we have determined the structure of HIV-1 protease complexed with an analog of the CA-p2 site, the reduced peptide inhibitor Arg-Val-Leu-r-Phe-Glu-Ala-Ahx-NH2 [r denotes the reduced peptide bond and Ahx 2-aminohexanoic acid (norleucine), respectively] [12].

Biological context of NORLEUCINE

• The relative ability of a norleucine substituted cholecystokinin (CCK) analogue, U-67827E, to interact with CCK receptors and to inhibit food intake was examined across a variety of paradigms [13].
• The antibody catalyzes the hydrolysis of norleucine phenyl ester with (S)-enantioselectivity [14].
• An analogue of bPTH-(1-34), in which the methionines at positions 8 and 18 were replaced with norleucine ([Nle8,Nle18,Tyr34]bPTH-(1-34)amide), was capable of reducing oxytocin-stimulated uterine contraction [15].
• This result implies that leucine or norleucine may acutely stimulate protein synthesis, at least in some tissues, by a mechanism that is independent of both S6K1 and 4E-BP1 phosphorylation [16].
• However, 3-phenylpyruvate, which increased 2-ketoisovalerate oxidative decarboxylation, inhibited 14CO2 production by islets exposed to D, L-[1-14C] norleucine [17].

Anatomical context of NORLEUCINE

• Parallel cytometric and fluorimetric analyses of the interaction of a fluoresceinated N-formyl hexapeptide (N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys-fluorescein, Nle = norleucine) with its receptors on human neutrophils are presented [18].
• [D-Phe6,beta-Ala11,Phe13, Nle14]Bn-(6-14) (where Nle represents norleucine) was discovered to have high potency for stimulating inositol phosphate formation in both cell lines [19].
• Cyclic peptide A4G82X (cyc-A4G82X;TLFLAHGRLVFX, where X is norleucine) significantly enhanced neurite outgrowth activity, but the rest of the cyclic peptides eliminated the activity [20].
• 2. The neutral hydrophobic amino acids tryptophan, leucine, phenylalanine, tyrosine, isoleucine, valine, norleucine and cycloleucine all rapidly inhibit the exit of alpha MG out of the epithelium into the vascular bed [21].
• Leucine or norleucine supplementation was accompanied by increased rates of protein synthesis in adipose tissue, liver, and skeletal muscle, but not in heart or kidney [22].

Associations of NORLEUCINE with other chemical compounds

• We have developed a radioiodinated photoaffinity label, N-formyl-Nle-Leu-Phe-Nle-125I-Tyr-Lys-N-6-(4'-azido-2'-nitrophenylamino) hexanoate (where Nle represents norleucine) (125I-PAL), which forms a covalent complex with the formyl peptide chemotactic receptor of living human neutrophils [23].
• We have examined the impact of C-H...pi and hydrophobic interactions in the diagonal position of a beta-hairpin peptide through comparison of the interaction of Phe, Trp, or Cha (cyclohexylalanine) with Lys or Nle (norleucine) [24].
• Randomization at three positions considered to be important for proteinase specificity (P2, P1 and P'2) with the genetically coded amino acids (minus cysteine) plus norleucine generated 8000 permutations [25].
• The RNA site is specific, discriminating against branched side chains of different size (valine--one methylene smaller than isoleucine) by at least 1.3 kcal/mol and against the shape (linear) of norleucine by 0.6 kcal/mol [26].
• The pH optimum for the enzymatic activity was 5.0 with elastin-Congo red as the substrate, and the activity was not significantly inhibited by pepstatin A, diazoacetyl norleucine methylester, and 1,2-epoxy-3-(p-nitrophenoxy) propane [27].

Gene context of NORLEUCINE

• Furthermore, this study reveals that these events were completely abrogated in cells exposed to Abeta peptides in which methionine 35 was substituted by a norleucine residue [28].
• Mutations of the metK gene encoding S-adenosylmethionine synthetase, which is involved in Met metabolism, were detected in 12 norleucine-resistant mutants [29].
• We have attempted to label the GRF receptor by chemically coupling the 125I-GRF analog [His1, Nle27]-hGRF(1-32)-NH2 (GRFa) (where Nle is norleucine) to plated rat anterior pituitary cells with the protein cross-linker disuccinimidyl suberate (DSS) (0.1 mM) [30].
• We have purified a 30-kDa serine protease (designated RNK-Met-1) from the granules of the rat large granular lymphocyte leukemia cell line (RNK-16) that hydrolytically cleaves model peptide substrates after methionine, leucine, and norleucine (Met-ase activity) [31].
• METHODS: Screening of combinatorial libraries has led to identification of D-Trp-Nle-NH2 (Nle, norleucine) and D-Trp-Arg-NH2 as the smallest structures known to antagonize the amphibian MCR (1) [32].

Analytical, diagnostic and therapeutic context of NORLEUCINE

• Norleucine-substituted adenylate kinase shows structural and catalytic properties similar to the wild-type protein as indicated by circular dichroism spectroscopy and kinetic experiments but exhibits a much higher resistance to hydrogen peroxide inactivation under denaturing conditions [33].
• The oxidized form was 90%, and the norleucine analogue was 70%, as potent as native IGF-I in a biological radioreceptor assay, and the form having mismatched disulphides lacked receptor affinity [34].
• Peaks corresponding to norleucine were seen by ion-exchange and gas chromatography but characteristic mass spectra were not obtained [35].
• Selective ion chromatograms of molecular ions of interest obtained in reversed-phase high-performance liquid chromatography/electrospray ionization mass spectrometry of proteolytic fragments offered a reliable and fast method of detection and quantitation of norleucine-containing peptides [11].
• Incorporation of norleucine occurs both at the amino terminal and internal methionines as confirmed by the isolation of norleucine-containing tryptic peptides which eluted later than the respective methionine-containing peptides by reverse-phase HPLC [36].

References