[Show abstract][Hide abstract] ABSTRACT: Human airway trypsin-like protease (HAT), also referred to as TMPRSS11D, is an important physiological enzyme with the main activity pronounced in an airway. In this work we have described the substrate specificity and selectivity study of the protease, performed by the combinatorial approach. Fluorogenic/chromogenic tetrapeptide library was used for this purpose. The most efficiently hydrolyzed substrates' sequences that we selected were ABZ-Arg-Gln-Asp-Arg(Lys)-ANB-NH(2). The most active inhibitor with C-terminal Arg residue underwent detectable proteolysis action in the presence of 35pM of HAT. Based on the selected sequences the two peptide aldehydes were synthesized and (Abz-Arg-Gln-Asp-Arg(Lys)-H) were found to be an effective HAT inhibitor, working in nanomolar range with inhibition constant 54nM and 112nM, respectively.
[Show abstract][Hide abstract] ABSTRACT: A set of benzoxazolyl-l-alanine derivates along with the MCA moiety (donors of fluorescence) were introduced into a proteinase 3 (PR3) substrate with a C-terminal ANB-NH(2) that serves as a fluorescence acceptor. Five substrates with general formula X-Tyr-Tyr-Abu-ANB-NH(2) were synthesized, and their kinetic parameters against proteinase 3 were determined. The highest k(cat)/K(M) value, 1.5 x 10(6) M(-1) s(-1), was obtained for (Pyr)Box-Ala-Tyr-Tyr-Abu-NH(2) where (Pyr)Box-Ala stands for N-methylpyrrole benzoxazole-l-alanine. Titration of this peptide with proteinase 3 resulted in measurable fluorescence at an enzyme amount equal to 29 pmol. This substrate was selected used to detect quantifiable levels of proteinase 3 in serum samples, including those of normal subjects. For all c-ANCA-positive samples (diagnosed Wegener granulomatosis), a significant increase of PR3 concentration was observed. Wegener granulomatosis is a severe autoimmune disease causing inflammation of the blood vessels. Our results clearly show that this substrate can be used for the construction of a very reliable, inexpensive, and easy to use diagnostic test for PR3 determination.
[Show abstract][Hide abstract] ABSTRACT: Four 28-amino acid peptides were synthesized whose sequences comprised two molecules of trypsin inhibitor sunflower trypsin inhibitor 1 (SFTI-1) bound through a peptide bond. The peptides in their reactive positions (5 and 19 of the peptide chain) contain two Lys ([KK]BiSFTI-1) and two Phe ([FF]BiSFTI-1) residues, along with a combination of the amino acid residues named thereafter [KF]BiSFTI-1 and [FK]BiSFTI-1. Association constants of the analogues determined with trypsin and chymotrypsin, respectively, indicated that they were potent inhibitors of cognate proteinases. An MS study of the associates revealed that incubation of the compounds with the proteinases resulted in cutting out a fragment of the peptide chain to restore the native monocyclic molecule of SFTI-1 or its analogue [Phe(5)]SFTI-1. This process, analogous to that of the DNA and protein splicing, can be referred to as 'peptide splicing'.
[Show abstract][Hide abstract] ABSTRACT: A peptomeric library consisting of 360 monocyclic analogues of trypsin inhibitor SFTI-1 isolated from sunflower seeds was designed and synthesized by a solid-phase approach in order to select chymotrypsin and cathepsin G inhibitors. All peptomers contained a proteinogenic-Phe-mimicking N-benzylglycine (Nphe) at positions 5 and 12. Into the synthesized library, different peptoid monomers were introduced in the 7-10 segment. Deconvolution of the library against both proteinases through an iterative method in solution revealed that the strongest chymotrypsin inhibitory activity was displayed by two analogues, [Nphe(5,12)]SFTI-1 (1) and [Nphe(5,12), Naem(8)]SFTI-1 (2), where Naem stands for N-(2-morpholinoethyl)glycine. After deconvolution against a cathepsin G analogue, [Nphe(5,12), Npip(8,9), Nnle(10)] SFTI-1 (3) (Npip = N-(3,4-methylenedioxybenzyl)glycine) appeared to be the most potent inhibitor with a high serum stability. It is worth noting that the analogues obtained by a combinatorial approach display high specificity towards one of the experimental enzymes. Another interesting feature is the lack of Pro8 in analogues 2 and 3, the amino acid residue absolutely conserved in the family of Bownan-Birk inhibitors.
[Show abstract][Hide abstract] ABSTRACT: A series of trypsin inhibitor SFTI-1compounds modified in substrate-specific P(1) position was synthesized by the solid-phase method. Lys5 present in the wild inhibitor was replaced by Phe derivatives substituted in para position of the phenyl ring, l-pyridylalanine and N-4-nitrobenzylgycine. Their inhibitory activities with bovine alpha-chymotrypsin and cathepsin G were estimated by determination of association equilibrium constants (K(a)). All analogues inhibited bovine alpha-chymotrypsin. The highest inihbitory activity displayed peptides with the fluorine, nitro and methyl substituents. They were 13-15-fold more active than [Phe(5)]SFTI-1 used as a reference. They are the most potent chymotrypsin inhibitors of this size. Substitution of Lys5 by Phe did not change the cathepsin G inhibitory activity. Introduction of Phe(p-F), Phe(p-NH(2)) and Phe(p-CH(3)) in this position retained the affinity towards this proteinase, whereas Phe(p-guanidine) gave an inhibitor more than twice as active, which appeared to be stable in human serum. On the other hand, a peptomeric analogue with N-4-nitrobenzylglycine failed to inhibit cathepsin G. Despite the fact the introduced amino acids were non-coded, the peptide bonds formed by them were hydrolyzed by chymotrypsin. We postulate that additional interaction of para-substitutents with the enzyme are responsible for the enhanced inhibitory activity of the analogues.
[Show abstract][Hide abstract] ABSTRACT: A series of linear and monocyclic analogues of trypsin inhibitor SFTI-1 isolated from sunflower seeds, modified by N-(4-aminobutyl)glycine (Nlys) and N-benzylglycine (Nphe), were obtained by the solid-phase method. Some of these peptomers displayed trypsin or chymotrypsin inhibitory activity. In contradiction to the literature data, in most analogues peptide bonds formed by these peptoid monomers were at least partially hydrolyzed by the experimental enzymes at two different pH (3.5 and 8.3). Nevertheless, the replacement of Phe present in the P(1) substrate specificity of linear inactive SFTI-1 analogue with Nphe, yielded a potent chymotrypsin inhibitor. The introduction of one cyclic element (a disulfide bridge or head-to-tail cyclization) to the analogues synthesized significantly increased their proteinase resistance.
[Show abstract][Hide abstract] ABSTRACT: A small peptide library of monocyclic SFTI-1 trypsin inhibitor from sunflower seeds modified in positions P(1) and P(4)' was synthesized using a portioning-mixing method. The peptide library was deconvoluted by the iterative approach in solution. Two trypsin ([Met(9)]-SFTI-1 and [Arg(5), Abu(9)]-SFTI-1), one chymotrypsin ([Phe(5)]-SFTI-1) and one human elastase ([Leu(5), Trp(9)]-SFTI-1) inhibitors were selected and resynthesized. The values of their association equilibrium constants (K(a)) with target enzymes indicate that they are potent inhibitors. In addition, the last two analoges belong to the most active inhibitors of this size. The results obtained show that the conserved Pro(9) residue in the Bowman-Birk inhibitor (BBI)s is not essential for inhibitory activity.
[Show abstract][Hide abstract] ABSTRACT: Five serine proteinase inhibitors (Mirabilis jalapa trypsin inhibitors, MJTI I and II and Spinacia oleracea trypsin inhibitors, SOTI I, II, and III) from the garden four-o'clock (M. jalapa) and spinach (S. oleracea) seeds were isolated. The purification procedures included affinity chromatography on immobilized methylchymotrypsin in the presence of 5M NaCl, ion exchange chromatography and/or preparative electrophoresis, and finally RP-HPLC on a C-18 column. The inhibitors, crosslinked by three disulfide bridges, are built of 35 to 37 amino-acid residues. Their primary structures differ from those of known trypsin inhibitors, but showed significant similarity to the antimicrobial peptides isolated from the seeds of M. jalapa (MJ-AMP1, MJ-AMP2), Mesembryanthemum crystallinum (AMP1), and Phytolacca americana (AMP-2 and PAFP-S) and from the hemolymph of Acrocinus longimanus (Alo-1, 2 and 3). The association equilibrium constants (K(a)) with bovine beta-trypsin for the inhibitors from M. jalapa (MJTI I and II) and S. oleracea (SOTI I-III) were found to be about 10(7)M(-1). Fully active MJTI I and SOTI I were obtained by solid-phase peptide synthesis. The disulfide bridge pattern in both inhibitors (Cys1-Cys4, Cys2-Cys5 and Cys3-Cys6) was established after their digestion with thermolysin and proteinase K followed by the MALDI-TOF analysis.
[Show abstract][Hide abstract] ABSTRACT: One of the hypotheses concerning the pathogenic properties of the prion protein considers its influence on cellular ion homeostasis. Using the lipid bilayer technique, the influence of prion-derived peptides on the lipid bilayer conductance was characterized. To evaluate the physiological significance and possible pathological functions of the peptides, their effect on the membrane potential and respiration rate of hippocampal mitochondria was also studied. We used a peptide bearing the human prion protein sequence YSNQNNF (PrP [169-175]), and peptide SSQNNF (PrP [170-175]) bearing a naturally-occurring mutation in position 171 [N(r)S] linked to schizoaffective diseases in humans (Samaia, H.B., Mari, J.J., Vallada, H.P., Moura R.P., Simpson A.J.G., Brentani R.R. A prion-linked psychiatric disorder. Nature 390 (1997) 241). In this report, we show that PrP [170-175] N171S increases the conductance of planar lipid bilayers. Based on the conductance of single channel currents recorded in 500/500 mM KCl (cis/trans), we found a single channel conductance of 8 to 26 pS. The native prion peptide PrP [169-175] does not form ion channels in the lipid bilayer. Neither of the peptides significantly changed the membrane potential or respiration rate of isolated rat hippocampal mitochondria. We propose a possible mechanism for channel formation by aggregation of the prion-derived peptide.
[Show abstract][Hide abstract] ABSTRACT: Cysteine proteinase found in the spinal cord of rat, called nociceptin-converting enzyme (NCE), is competitively inhibited by dynorphin A and its fragment des-[Tyr(1)]-DYN A. This proteinase converts orphanin FQ/nociceptin (OFQ/N) to two major fragments: OFQ/N(1-11) and further OFQ/N(1-6) with analgesic properties. Dynorphin A at the concentration of 10 microM increases K(M) from 15.0 to 55.9 microM. The calculated K(i) for this interaction was estimated at 3.7 microM. This observation may suggest an interaction between opioid and nociceptive systems which may be affected by the balance between opioid and antiopioid systems. This balance between particular OFQ/N sequences that are derived from the same precursor and regulated by proteinases may play an important role in pain. Interestingly, dynorphin B does not reveal a similar action on the NCE.
Biochemical and Biophysical Research Communications 11/2001; 287(4):927-31. DOI:10.1006/bbrc.2001.5677 · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Two analogs of a tachykinin family peptides - scyliorhinin II (ScyII): [Aib(16)]ScyII and [Sar(16)]ScyII were synthesized by the solid-phase method using Fmoc chemistry. Conformational studies in water and DMSO-d(6) on these peptides were performed using a combination of two-dimensional NMR and theoretical conformational analysis. The solution structure of the peptides studied is interpreted as an equilibrium of several conformers with different statistical weights. The structure of [Sar(16)]ScyII in water appeared to be more flexible, especially in the C-terminal fragment. A better defined structure for this analog was obtained in DMSO-d(6), in which the analysis resulted in a family of conformers with similar shapes. Some of these conformers were characterized by the presence of a 3(10)-helix in the N-terminal fragment and middle part of the molecule. The introduction of the Aib residue in position 16 significantly rigidifies the structure. For [Aib(16)]ScyII in both solvent systems very similar populations of conformations were obtained which are characterized by the presence of a 3(10)-helix in the 13-18 fragment. A common structural motif was found in conformationally constrained Cys(7)-Cys(13) fragment, which resembles the Greek letter 'omega'. The differences in the solution structure of the C-terminal fragment of the peptides studied are responsible for their specificity. [Aib(16)]ScyII showed 25% the agonistic activity of selective NK-3 agonist - senktide, but it also showed antagonist effect vs. this peptide, whereas [Sar(16)]ScyII appeared to be a full agonist of NK-3 tachykinin receptor.
European Journal of Allergy and Clinical Immunology 09/2001; 58(2):159-72. DOI:10.1034/j.1399-3011.2001.00886.x · 1.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A C-terminal analog of the hexapeptide orphanin FQ/nociceptin-(1-6), [Ala(6)]-orphanin FQ/nociceptin-(1-6), and a pentapeptide orphanin FQ/nociceptin-(1-5) were tested in vivo for their analgesic/hyperalgesic activity in the hot-plate test with rats. Replacement of the C-terminal glycine by L-alanine (Phe-Gly-Gly-Phe-Thr-Ala) in orphanin FQ/nociceptin-(1-6) abolished the hyperalgesic potency of native orphanin FQ/nociceptin-(1-6) (Phe-Gly-Gly-Phe-Thr-Gly), but analgesic activity was retained and was diminished by naloxone. Removal of the C-terminal amino acid (glycine or alanine) from orphanin FQ/nociceptin-(1-6) caused a significant loss of analgesic activity. It is anticipated that glycine plays a crucial role in the biphasic activity of orphanin FQ/nociceptin-(1-6). This may suggest the existence of a mechanism for terminating the biological action of orphanin FQ/nociceptin.
European Journal of Pharmacology 06/2001; 419(1):33-7. DOI:10.1016/S0014-2999(01)00955-4 · 2.68 Impact Factor