1.Analogue of Melanotan II (MTII): A Novel Melanotropin with Superpotent Action on Frog Skin.
Gao L, Yu Z, Meng D, Zheng F, Ong YS, Miao P, Lee SS, Wen L1. Protein Pept Lett. 2015;22(8):762-6.
An α-MSH peptide analogue, named MTII (Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]- NH2), is one of the most important ligands of melanotropic receptors but are relatively nonselective. In order to improve the melanotropic activities of the well-characterized MTII analogues, we report here a new analogue by modifying the core structure as well as the size of the cyclic region of MTII peptide. The analogue peptide, Ac-Nle-c[Asp-His-D-Phe-Lys-Trp-Gly-Lys]-OH (F Peptide), in which we replaced Arg at position 8 with Lys and added a Gly to position 10 of the MTII peptide sequence, was synthesized and used as a new melanotropic hormone in controlling rapid color changes in frogs by its actions on mobilizing pigment granule movements within chromatophores. The in vivo responses of chromatophores to MTII and the related analogue F Peptide were studied in frogs. The results show that the F Peptide was a superpotent agonist with similar melanotropic activity to the MTII peptide according to MTII peptide by in vivo studies.
2.Characterization of chicken ACTH and alpha-MSH: the primary sequence of chicken ACTH is more similar to Xenopus ACTH than to other avian ACTH.
Hayashi H1, Imai K, Imai K. Gen Comp Endocrinol. 1991 Jun;82(3):434-43.
Adrenocorticotropic (ACTH) and melanocyte stimulating (MSH) hormones have been demonstrated in the same cells in the cephalic half of the pars distalis of the chicken pituitary glands in three ways: (I) immunohistochemistry, (II) radioimmunoassay (RIA) using both anti-human or porcine ACTH and synthetic alpha-MSH antibodies, and (III) isolation and purification, followed by the determination of amino acid compositions of both hormones. The contents of ACTH and alpha-MSH are estimated by RIA to be 1600 and 10 ng/gland, respectively. ACTH missed 1 (des-Phe39-ACTH) or 2 residues (des-Glu38, Phe39-ACTH) from the C-terminal portion was also isolated. The recoveries of these ACTHs are differed from preparation to preparation. The complete amino acid sequence of chicken ACTH (39 residues) has been determined as NH2-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-Gly-Arg-Lys-Arg- Arg- Pro-Ile-Lys-Val-Tyr-Pro-Asn-Gly-Val-Asp-Glu-Glu-Ser-Ala-Glu-Ser-Tyr-Pro- Met-Glu-Phe-OH Strikingly the amino acid sequence of chicken ACTH shows a closer resemblance to that from an amphibian, Xenopus (3 residue substitution) than that from another bird, the ostrich (7 residue substitution) or the turkey (at least 9 residue substitution).
3.An unmodified heptadecapeptide pheromone induces competence for genetic transformation in Streptococcus pneumoniae.
Håvarstein LS1, Coomaraswamy G, Morrison DA. Proc Natl Acad Sci U S A. 1995 Nov 21;92(24):11140-4.
Competence for genetic transformation in Streptococcus pneumoniae has been known for three decades to arise in growing cultures at a critical cell density, in response to a secreted protease-sensitive signal. We show that strain CP1200 produces a 17-residue peptide that induces cells of the species to develop competence. The sequence of the peptide was found to be H-Glu-Met-Arg-Leu-Ser-Lys-Phe-Phe-Arg-Asp-Phe-Ile-Leu-Gln-Arg- Lys-Lys-OH. A synthetic peptide of the same sequence was shown to be biologically active in small quantities and to extend the range of conditions suitable for development of competence. Cognate codons in the pneumococcal chromosome indicate that the peptide is made ribosomally. As the gene encodes a prepeptide containing the Gly-Gly consensus processing site found in peptide bacteriocins, the peptide is likely to be exported by a specialized ATP-binding cassette transport protein as is characteristic of these bacteriocins.
4.Influence of sequential oligopeptide carriers on the bioactive structure of conjugated epitopes: comparative study of the conformation of a Herpes simplex virus glycoprotein gD-1 epitope in the free and conjugated form, and protein "built-in" crystal structure.
Krikorian D1, Stavrakoudis A, Biris N, Sakarellos C, Andreu D, de Oliveira E, Mezö G, Majer Z, Hudecz F, Welling-Wester S, Cung MT, Tsikaris V. Biopolymers. 2006;84(4):383-99.
Synthetic carriers play an important role in immunogen presentation, due to their ability of inducing improved and specific responses to conjugated epitopes. Their influence on the bioactive conformation of the epitope, though admittedly crucial for relevant in vitro and in vivo applications, is difficult to evaluate, given the usual lack of information on the complex conformational features determined by the nature of the carrier and the mode of ligation. Using the Herpes simplex virus glycoprotein D-1 epitope (Leu(9)-Lys-Nle-Ala-Asp-Pro-Asn-Arg-Phe-Arg-Gly-Lys-Asp-Leu(22)) as a model, we have performed a detailed conformational analysis on the free epitope peptide in solution and on three constructs in which the epitope was conjugated to sequential oligopeptide carriers {Ac-[Lys-Aib-Gly](4)-OH (SOC(4))} (through either a thioether or an amide bond; Ac: acetyl) and polytuftsin oligomers {H-[Thr-Lys-Pro-Lys-Gly](4)-NH(2) (T20)}, (through a thioether bond).
