Gotfryd Kupryszewski

Angiotensin ii-(3–8)-hexapeptide affects motor activity, performance of passive avoidance and a conditioned avoidance response in rats

Angiotensin II-(3-8)-hexapeptide, at the dose of 1 nmol given intracerebroventricularly, only slightly less than angiotensin II (the same dose and route) stimulated exploratory locomotor behaviour in an open field and electromagnetic motimeter. Both peptides considerably enhanced stereotyped behaviour produced by apomorphine and amphetamine. Angiotensin II-(3-8)-hexapeptide improved recall in a passive avoidance situation as well as angiotensin II. The 3-8 C-terminus of angiotensin II enhanced acquisition of active avoidance nearly as effectively as the complete peptide. The results indicate that the effectiveness of equimolar doses of angiotensin II-(3-8)-hexapeptide and angiotensin II in improving processes related to learning and memory in rats is almost identical and thus must be independent of specific angiotensin receptors in brain to which the hexapeptide binds with about 1000 times lower affinity than angiotensin II. The stimulation of stereotypy, a dopamine-controlled behaviour, by the peptides points to the possibility of dopaminergic mediation of their psychotropic effects.

Psychotropic effects of angiotensin II and III in rats: locomotor and exploratory vs cognitive behaviour.

One nmol of angiotensin II (AII) or angiotensin III (AIII) given intracerebroventricularly (i.c.v.) increased locomotor and exploratory activity in an open field apparatus but not in the electromagnetic field motimeter. Both peptides significantly enhanced stereotyped behaviour produced by apomorphine (2 mg/kg) and amphetamine (6.5 mg/kg) given intraperitoneally. Also, AII and AIII improved consolidation but not retrieval of memory for an appetitively reinforced spatial discrimination task in a T-maze. AII as well as AIII, given prior to the learning session on day 1, increased rate of acquisition of conditioned avoidance responses in a shuttle-box over the next 7 days. Both angiotensins, injected i.c.v. 15 min before the retention testing, remarkably (5-fold) prolonged re-entry latencies in the passive avoidance situation, suggesting facilitation of the retrieval of memory for an aversively motivated behaviour.

Complexes of Cu(II) with Asn-Ser-Phe-Arg-Tyr-NH2; an example of metal ion-promoted conformational organization which results in exceptionally high complex stability

The pentapeptide fragment of ANF, Asn-Ser-Phe-Arg-Tyr-NH2, coordinates to Cu(II) using the same four nitrogen donor centers as simple pentapeptides such as pentaalanine yet the complexes are of much higher stability as a result of a highly organized side-chain structure which is present in the complex but absent from the free ligand.

Behavioral effects of angiotensin II and angiotensin II-(4-8)-pentapeptide in rats☆

One nM of angiotensin II (AII) or angiotensin II-(4-8)-pentapeptide [AII(4-8)] given intracerebroventricularly did not affect locomotor and exploratory behavior of rats in open field. AII significantly increased and AII(4-8) did not affect vertical activity of animals in electromagnetic motimeter. Neither of the peptides influenced horizontal activity in the motimeter. Both peptides intensified stereotypy produced by apomorphine and amphetamine. AII significantly improved, while AII(4-8) did not affect, consolidation of memory of the correct way to food in T-maze. Similarly, AII increased and AII(4-8) did not change the rate of acquisition of conditioned avoidance responses in a shuttle-box. Of the two examined peptides only AII significantly improved retrieval of memory of the passive avoidance behavior. The results show that AII(4-8) influences central dopaminergic system but, unlike its parent peptide AII, has no apparent effect on memory.

Separation of siderophores by capillary electrophoresis

Abstract Capillary electrophoresis (CE) was applied as a fast method of siderophore separation. Siderophores are iron binding and regulating cell products, which facilitate iron transport into cells. A fast and efficient method of siderophore analysis is important for better understanding of the iron pathways in a sea environment or marine organisms. The best results of CE analysis were obtained using free zone CE in 25 m M phosphate buffer at basic pH using a constant voltage of 20 kV. Under these conditions it was possible to detect the presence of siderophores in seawater.

Cu(II) binding by angiotensin II fragments: Asp-Arg-Val-Tyr-Ile-His and Arg-Val-Tyr-Ile-His. Competition between amino group and imidazole nitrogens in anchoring of metal ions.

Potentiometric and spectroscopic (absorption, circular dichroism and electron paramagnetic resonance) study on the coordination of two angiotensin II fragments (Asp-Arg-Val-Tyr-Ile-His and Arg-Val-Tyr-Ile-His) to Cu(II) ions has shown that competition between amino and imidazole nitrogens to anchor metal ions is a complicated process and may lead to formation of macrochelate rings. The important factor that influences this competition is the distance between competing His and N-terminal residues (number of spacer residues in a peptide sequence).

Human heat shock protein 60 (409–424) fragment is recognized by serum antibodies of patients with acute coronary syndromes

Acute coronary syndromes (ACS), including unstable angina (UA) and acute myocardial infarction (MI), are clinical manifestations of a progressive atherosclerotic process. Antibodies (Ab) to heat shock proteins (hsp) have been reported to be associated with atherosclerosis. Blood samples from 35 patients with ACS and 20 healthy volunteers were tested for Ab to human hsp60 by an enzyme-linked immunosorbent assay (ELISA). Levels of specific serum Ab against hsp60 were significantly elevated in patients with ACS when compared to clinically healthy subjects. To determine the antigenic determinants recognized by these Ab, antibody binding to seven peptides, selected from the hydrophilic and acrophilic regions of the human hsp60 molecule, was assessed. Despite the individual variation in the immune response among patients, one immunodominant region was revealed corresponding to the hsp60 (409-424) peptide. The identification of this epitope may be important for understanding the function of this protein in the atherosclerotic process.

The coordination of copper(II) with β-casomorphin and its fragments

The synthesis of β-casomorphin-5 (Tyr-Pro-Phe-Pro-Gly, H2L) and a number of its peptide fragments is described. Complexes formed between these peptides and Cu(II) have been investigated spectrophotometrically, using CD and EPR spectroscopy, and potentiometrically. Results show that, with tyrosine as the N-terminal residue, the major complex formed at physiological pH is the dimeric species, [Cu2L2], bonded through the phenolic O− of the Tyr residue of one ligand and the N-terminal amine nitrogen of the second ligand molecule. There is no evidence for coordination through the peptide nitrogens unless the terminal Tyr group is removed.

TRH analogue with C-terminal thioamide group. Synthesis, receptor binding, TSH-releasing activity and α-MSH-releasing activity

A new TRH analogue containing a C-terminal thioamide group was synthesized. This peptide was shown to have receptor-binding affinity, and TSH- as well as α-MSH-releasing activities very similar to native TRH.

Coordination ability of the thyrotropin releasing factor. II. Nickel(II) complexes with TRF

Abstract The interactions of Ni(II) with PyrHisProNH 2 (TRF) and PyrHis dipeptide analogue have been studied with use of absorption and CD spectroscopy as well as the 1 H NMR spectra. The formation of two planar complexes characterized by different CD spectra has been found in basic solutions. In both planar species the coordination sites are three nitrogen donors i.e. N 3 of imidazole, N − of the peptide linkage between Pyr and His residues and N − of Pyr residue. The difference in CD spectra of two planar complexes has been explained in terms of chelate ring conformation change due to the deprotonation of N1 imidazole nitrogen. The N1 deprotonation is promoted by the Ni(II) coordination to N3 nitrogen of imidazole ring.