Danuta Konopińska

Proctolin, an insect neuropeptide

Synthetic, biological and conformational studies on the insect neuropeptide proctolin (Arg‐Tyr‐Leu‐Pro‐Thr) and some of its analogues are reviewed. Copyright

Analysis of peptidic epitopes recognized by the three monoclonal antibodies specific for the same region of glycophorin a but showing different properties

Analysis of epitopes for the three monoclonal antibodies (GPA105, GPA33, OSK4-1) against glycophorin A (GPA) was performed with the use of proteolytic fragments of GPA, the synthetic nonapeptide with the sequence of amino acid residues 35-43 of GPA, and a series of peptides synthesized on plastic pins. The antibodies were specific for a short peptide sequence RAHE (a.a. 39-42 of GPA, MAbs GPA105 and OSK4-1) or RAHEV (a.a. 39-43 of GPA, MAb GPA33). Despite recognizing the same fragment of GPA, the three antibodies showed differences in fine specificity and in response to antigen desialylation. Reactions with single replacement analogs of the RAHEV sequence showed that immunodominant (unreplaceable) residues for the MAbs GPA33 and OSK4-1 were His and Glu, respectively, whereas no such residue was found for the MAb GPA105. Desialylation of the antigen gave strong enhancement of reactivity with the MAb GPA33, moderate--with the MAb GPA105, and weak or no enhancement of reaction with the MAb OSK4-1. The results showed that monoclonal antibodies directed against the same fragment of the polypeptide chain of densely glycosylated antigen may recognize different subsites which are masked at different degree by sialic acid residues.

Studies of insect peptides alloferon, Any-GS and their analogues. Synthesis and antiherpes activity

The subject of these studies was synthesis and determination of biological properties of a series of insect peptides, such as alloferon, Any‐GS and their analogues. The synthesis of 14 peptides was performed by the solid‐phase method. Biological effect of these peptides was evaluated by the antiviral test against Human Herpes Virus type 1 (HHV‐1) in vitro using a Vero cell line. It was found that the investigated peptides inhibit the replication of HHV‐1 in Vero cells. Copyright

Mononuclear copper(II) complexes of alloferons 1 and 2: A combined potentiometric and spectroscopic studies

Mononuclear copper(II) complexes of the alloferon 1 His-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly, alloferon 2 Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly, Ac-alloferon 1 Ac-His-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly and Ac-alloferon 2 Ac-Gly-Val-Ser-Gly-His-Gly-Gln-His-Gly-Val-His-Gly have been studied by potentiometric, UV-vis, CD and EPR spectroscopic methods. The potentiometric and spectroscopic data shows that acetylation of the amino terminal group induces significant changes in the coordination properties of the Ac-alloferons 1 and 2 compared to the alloferons 1 and 2, respectively. The presence of four (Ac-alloferon 1) or three (Ac-alloferon 2) histidyl residues provides a high possibility for the formation of macrochelates via the exclusive binding of imidazole-N donor atoms. The macrochelation suppresses, but cannot preclude the deprotonation and metal ion coordination of amide functions and the CuH(-3)L species with [N(Im), 3N(-)] bonding mode at pH above 8 are formed. The N-terminal amino group of the alloferons 1 and 2 takes part in the coordination of the metal ion and the 4N complex with [NH(2), 3N(Im)] coordination mode dominates at physiological pH 7.4 for alloferon 1 and the 3N [NH(2), CO, 2N(Im)] binding mode for alloferon 2. However, at higher pH values sequential amide nitrogens are deprotonated and coordinated to copper(II) ions.

Pharmacological studies of proctolin receptors on foregut and hindgut of Blaberus craniifer.

Proctolin (Arg-Tyr-Leu-Pro-Thr) and proctolin analogs modified at position 1, 2, or 5 caused dose dependent contractions of Blaberus fore- and hindgut. The varying contractile effects between both tissues revealed the possible presence of receptor subtypes as identified by [GABA1]-proctolin. A single population of binding sites (Kd approximately 100 nM) was deduced from Scatchard analysis. In addition, nanomolar concentrations of proctolin induced a dose-dependent hydrolysis of phosphoinositides (PIns) augmented by GTPgammaS (1 microM) on foregut membranes but no accumulation of cAMP. Proctolin induced contractions are likely mediated via a phospholipase C linked to a heptahelical receptor bound to heterotrimeric G-proteins.

Further studies on the antiviral activity of alloferon and its analogues

The subject of our studies was the synthesis, biological evaluation, and conformational studies of insect tridecapeptide alloferon (H‐His‐Gly‐Val‐Ser‐Gly‐His‐Gly‐Gln‐His‐Gly‐Val‐His‐Gly‐OH) and its analogues such as: [des‐His1]‐, [Lys1]‐, [Arg1]‐, and [Ala1]‐alloferon. These peptides were synthesized to check the influence of the His residue at position 1 of the alloferon chain on its antiviral activity. Two aspects of the biological effects of these peptides were determined: (i) the cytotoxicity in vitro in the Vero, LLC‐MK2, and HEp‐2 cell lines, and (ii) the antiviral activity in vitro in respect to DNA and RNA viruses. We found that alloferon inhibited the herpes virus multiplication and failed to affect the coxsackie virus replication, whereas [Lys1]‐alloferon exhibited a high inhibitory action towards both viruses. Moreover, the peptides did not show any cytotoxic activity against the Vero, LLC‐MK2, and HEp‐2 cells. The preliminary circular dichroism conformational studies showed that the peptides investigated seem to prefer an unordered conformation. Copyright

Synthesis, cardiostimulatory, and cardioinhibitory effects of selected insect peptides on Tenebrio molitor

The subject of these studies was a search for proctolin antagonists among peptides originating from insect species because the proctolin antagonists constantly pose a problem. During these studies we performed the synthesis of the following peptides: a native decapeptide from Manduca sexta Mas‐MT‐I and its 11 analogs with shortened sequences at the N‐end as well as a growth suppressor, a pentapeptide isolated from Antheraea yamamai, Any‐GS and its 10 analogs, modified at position 1 and with a shortened peptide chain.

Biological Activity of Structural Analogs and Effect of Oil as a Carrier of Trypsin Modulating Oostatic Factor of the Gray Fleshfly Neobellieria bullata

The trypsin modulating oostatic factor from the gray fleshfly Neobellieria bullata (Neb-TMOF) is released from the ovary at the end of vitellogenesis and inhibits trypsin biosynthesis in the midgut. This inhibition indirectly results in an arrest of oocyte growth. Additional experiments with N. bullata were performed to characterize its trypsin modulating and oostatic properties in more detail. After suspending the peptide in wheat germ oil, the threshold dose for oostatic activity was lowered one thousand times (2.10(-5) in oil versus 2.10(-2) pmoles per fly in Ringer). By use of the Neobellieria trypsin biosynthesis assay, 17 analogs of the hexapeptide were tested for inhibitory activity. The following structural elements were demonstrated to be critical for biological activity: the alcohol function at position 3 (Thr residue); a positively charged basic group at the C terminus (His residue); and the Asn side chain at positions 1 and 4.

MYOTROPIC EFFECTS OF PROCTOLIN ANALOGUES, MODIFIED IN POSITION 2 OF THE PEPTIDE CHAIN, ON THE FOREGUT OF THE LOCUST SCHISTOCERCA GREGARIA

Abstract Proctolin (H.Arg.Tyr.Leu.Pro.Thr.OH) caused dose-dependent contraction of the isolated foregut of the locust Schistocerca gregaria at concentrations ranging from 10 −8 , m to 2 × 10 −6 , m . Of the ten analogues evaluated, [Phe( p -NH 2 ) 2 ]-, [Tyr( m -NH 2 ) 2 ]- and [Phe( p -OEt) 2 ]-proctolin are dose-dependent supra agonists while [Phe( p -OMe) 2 ]- and [ l -DOPA 2 ]-proctolin are supra agonists only when applied at a single dose of 5 × 10 −7 , m . Construction of dose response curves showed that [Phe( p -OMe) 2 ]-, [ l -DOPA 2 ]-, [Phe( p -NH 2 ) 2 ]- and [Phe( p -NO 2 ) 2 ]-proctolin are partial agonists incapable of causing a maximum response equivalent to that induced by the parent pentapeptide. [Cha(4-OMe) 2 ]-, [Afb( p -OH) 2 ]- and [Afb( p -NO 2 ) 2 ]-Proctolin are weak agonists with intrinsic activities equivalent to only 12.7%, 7.9% and 3.5% respectively of that of proctolin. [α-Me- l -Tyr 2 ]- and [Afb( p -NO 2 ) 2 ]-Proctolin (10 −8 , m –10 −6 , m are potent non-competitive antagonists of proctolin induced tissue contraction, reducing the maximum response of applied proctolin to 16% and 23% respectively when used at a dose of 10 −6 , m . From analysis of the myotropic effects of the analogues investigated in this study, we conclude that the agonist actions of proctolin are dependent on the presence of either a para substituted Phe or a meta substituted Tyr in position 2 of the peptide chain. These data show that the ideal substituents on the aromatic ring are groups containing oxygen and nitrogen atoms.

Insect Trypsin Modulating Oostatic Factor (Neb-TMOF) and Its Analogs: Preliminary Structure/Biological Function Relationship Studies

Neb-TMOF, the trypsin modulating oostatic factor of gray fleshflyNeobellieria bullata, is a hexapeptide with the following sequence: H-Asn-Pro-Thr-Asn-Leu-His-OH. It has been isolated from vitellogenic ovaries in 1994. TMOF, the newly discovered insect peptide, inhibits trypsin biosynthesis in the gut, lowers yolk polypeptide concentration in the hemolymph and strongly inhibits ecdysone biosynthesis by larval ring glands. It is interesting that this short non-protected peptide contains in its molecule two Asn residues at positions 1 and 4 and His at its C-terminus. To obtain information about the role of the His-6 and Asn-4 residues we synthesised two series of Neb-TMOF analogs, modified: (1) in position 6 byd-His (I), His(Bzl) (II) and Phe(p-X) derivatives, where X=NH2 (III), NO2 (IV), OEt (V) and OH (VI) and (2) in position 4 by such amino acid residues as Ser (VII), Thr (VIII), Gly (IX), Asp (X), Glu (XI) andd-Asn (XII). The influence of these peptides on trypsin biosynthesis inN. bullata was determinedin vivo. In preliminary investigations, we found that Neb-TMOF, [Phe(NH2)6], and [Phe(NO2)6]-Neb-TMOF inhibited trypsin biosynthesis, whereas [d-His)6]- and [d-His(Bzl)6]-Neb-TMOF were inactive. In further biological studies performedin vitro on heart ofTenebrio molitor were found that-TMOF and [Phe(p-NH2)6]-Neb-TMOF showed weak cardioexcitatory activity, about 30% of the cardioexcitatory activity of proctolin, an insect neuromodulating peptide.