1. beta-Lipotropin: primary structure of the hormone from the ostrich pituitary gland
C H Li,D Chung,W Oelofsen,R J Naudé Int J Pept Protein Res . 1981 Aug;18(2):138-47. doi: 10.1111/j.1399-3011.1981.tb02051.x.
The amino acid sequence of beta-lipotropin from the ostrich pituitary has been determined. It consists of 79 amino acids. The amino acid sequence has been determined as follows: H-(1)AlA-Leu-Pro-Pro-Ala-Ala-Met-Leu-Pro-(10)Ala-Ala-Ala-Glu-Glu-Glu-Glu-Gly-Gl u-Glu-(20)Glu-Glu-Glu-Gly-Glu-Ala-Glu-Lys-Glu-Asp-(30)Gly-Gly-Ser-Tyr-Arg-Met-A rg-His-Phe-Arg-(40)Trp-Gln-Ala-Pro-Leu-Lys-Asp-Lys-Arg-Tyr-(50)Gly-Gly-Phe-Met- Ser-Ser-Glu-Arg-Gly-Arg-(60)Ala-Pro-Leu-Val-Thr-Leu-Phe-Lys-Asn-Ala-(70)Ile-Val -Lys-Ser-Ala-Tyr-Lys-Lys-Gly-(79)Gln-OH. When compared with the primary structures of other known beta-lipotropins, the sequence at the NH2-terminal, beta-melanotropin and beta-endorphin portions of the molecule exhibit considerable variability.
2. "To serve and protect": enzyme inhibitors as radiopeptide escorts promote tumor targeting
Eric P Krenning,Theodosia Maina,Marion de Jong,Berthold A Nock J Nucl Med . 2014 Jan;55(1):121-7. doi: 10.2967/jnumed.113.129411.
Radiolabeled octreotide analogs are most successfully being applied today in clinical cancer imaging and treatment. Propagation of this paradigm to other radiopeptide families has been greatly hampered by the inherent poor metabolic stability of systemically administered peptide analogs. We hypothesized that the in vivo coadministration of specific enzyme inhibitors would improve peptide bioavailability and hence tumor uptake. Through single coinjection of the neutral endopeptidase inhibitor phosphoramidon (PA), we were able to provoke remarkable rises in the percentages of circulating intact somatostatin, gastrin, and bombesin radiopeptides in mouse models, resulting in a remarkable increase in uptake in tumor xenografts in mice.Methods:The peptide conjugates [DOTA-Ala(1)]SS14 (DOTA-Ala-Gly-c[Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Ser-Cys]-OH), PanSB1 (DOTA-PEG2-dTyr-Gln-Trp-Ala-Val-βAla-His-Phe-Nle-NH2), and DOTA-MG11 (DOTA-dGlu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2) were labeled with (111)In by 20 min of heating at an acidic pH. Metabolic stability was studied with high-performance liquid chromatography analysis of blood samples collected 5 min after the injection of the test radiopeptide alone or with PA into mice. Biodistribution was studied after injection of each (111)In-labeled radiopeptide alone or after coinjection of PA in tumor-bearing severe combined immunodeficient (SCID) mice.Results:The amount of intact [(111)In-DOTA-Ala(1)]SS14 detected in the mouse circulation at 5 min after the injection of PA increased impressively-from less than 2% to 86%-whereas the uptake in AR4-2J xenografts rose from less than 1 percentage injected dose per gram of tissue (%ID/g) to 14 %ID/g at 4 h after injection. Likewise, the coadministration of PA resulted in a marked increase in the amount of circulating intact (111)In-PanSB1-from 12% to 80%-at 5 min after injection, and radioligand uptake in human PC-3 xenografts in SCID mice escalated from less than 4 %ID/g to greater than 21 %ID/g at 4 h after injection. In a similar manner, the coadministration of PA resulted in an equally impressive increase in intact [(111)In-DOTA]MG11 levels in the mouse bloodstream-from less than 5% to 70%-at 5 min after injection, leading to a remarkable increase in radiotracer uptake-from 2 %ID/g to greater than 15 %ID/g-in both AR4-2J tumors and A431(CCKR+) tumors (i.e., tumors induced by A431 cells transfected to stably express the human cholecystokinin subtype 2 receptor) in mice at 4 h after injection. This effect was well visualized by SPECT/CT imaging of AR4-2J tumor-bearing mice at 4 h after injection.Conclusion:The results of this study clearly demonstrate that the coadministration of key enzyme inhibitors can effectively prolong the survival of radiolabeled peptides in the circulation, securing their safe transit to the target. This strategy clearly provoked an unprecedented increase in radiolabel accumulation in tumor xenografts in mice; this increase might translate into higher diagnostic sensitivity or improved therapeutic efficacy of radiopeptide drugs in cancer patients. Hence, our findings provide exciting new opportunities for the application of biodegradable (radio)peptide drugs of either natural or synthetic origin as well as for the rationale design of analogs that are stable in vivo.
3. Acid-base properties of the (1-4,18-36) fragments of neuropeptide K and their mono- and polynuclear copper(II) complexes products of metal-catalyzed oxidation
Teresa Kowalik-Jankowska,Marta Błaszak,Elżbieta Jankowska Inorg Chem . 2013 Jan 7;52(1):130-43. doi: 10.1021/ic301476p.
Mononuclear and polynuclear complexes of the (1-4,18-36)NPK, Asp(1)-Ala-Asp-Ser(4)-Gly(18)-His(19)-Gly-Gln-Ile-Ser-His(24)-Lys-Arg-His(27)-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met(36)-NH(2), and mononuclear complexes of its acethyl derivative Ac-Asp(1)-Ala-Asp-Ser(4)-Gly(18)-His(19)-Gly-Gln-Ile-Ser-His(24)-Lys-Arg-His(27)-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met(36)-NH(2) have been studied by potentiometric, UV-vis, CD, EPR spectroscopic, and mass spectrometry (MS) methods. As it was observed for other tachykinins (neurokinin A, neuropeptide gamma and its fragments) containing the same C-terminal sequence His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH(2), also for the fragments of neuropeptide K the additional deprotonation most likely on the serine OH group was observed. It is likely that tachykinin peptides contain catalytic Ser/His/Asp triad or dyads Ser/Lys and the serine protease activity. The high water solubility of the resulting metal complexes allowed us to obtain complete complex speciation at different metal-to-ligand ratios ranging from 1:1 to 4:1 for (1-4,18-36)NPK, while only the 1:1 molar ratio was studied for Cu(II)-Ac-(1-4,18-36)NPK because of precipitation. For the metal-to-ligand 1:1 molar ratio the (1-4,18-36)NPK forms in a wide 6.5-10.5 pH range the CuHL complex with a 3N {NH(2),2N(-),β-COO(-)-Asp(3)} binding site. For a metal-to-ligand 1:1 molar ratio at higher pH than 9.5 the dimeric species dominate. For the Ac-(1-4,18-36)NPK peptide the imidazole nitrogen atoms are the primary metal-binding sites forming macrochelates in the pH 4-7.5.
4. Discovery of mitocryptide-1, a neutrophil-activating cryptide from healthy porcine heart
Hirokazu Kimura,Yasutsugu Shimonishi,Yoshinori Hokari,Tetsuo Seki,Masahiko Kato,Makoto Kubota,Yoshiaki Kiso,Kaori Wakamatsu,Hiroyuki Tsukagoshi,Yoshisuke Nishi,Eisuke Munekata,Hidehito Mukai,Toshifumi Takao,Yuko Matsuo J Biol Chem . 2008 Nov 7;283(45):30596-605. doi: 10.1074/jbc.M803913200.
Although neutrophils are known to migrate in response to various chemokines and complement factors, the substances involved in the early stages of their transmigration and activation have been poorly characterized to date. Here we report the discovery of a peptide isolated from healthy porcine hearts that activated neutrophils. Its primary structure is H-Leu-Ser-Phe-Leu-Ile-Pro-Ala-Gly-Trp-Val-Leu-Ser-His-Leu-Asp-His-Tyr-Lys-Arg-Ser-Ser-Ala-Ala-OH, and it was indicated to originate from mitochondrial cytochrome c oxidase subunit VIII. This peptide caused chemotaxis at concentrations lower than that inducing beta-hexosaminidase release. Such responses were observed in neutrophilic/granulocytic differentiated HL-60 cells but not in undifferentiated cells, and G(i2)-type G proteins were suggested to be involved in the peptide signaling. Moreover the peptide activated human neutrophils to induce beta-hexosaminidase secretion. A number of other amphipathic neutrophil-activating peptides presumably originating from mitochondrial proteins were also found. The present results suggest that neutrophils monitor such amphipathic peptides including the identified peptide as an initiation signal for inflammation at injury sites.
