9-Fluorenylmethoxycarbonyl (Fmoc) amino acids were first used for solid phase peptide synthesis a little more than a decade ago. Since that time, Fmoc solid phase peptide synthesis methodology has been greatly enhanced by the introduction of a variety of solid supports, linkages, and side chain protecting groups, as well as by increased understanding of solvation conditions. These advances have led to many impressive syntheses, such as those of biologically active and isotopically labeled peptides and small proteins. The great variety of conditions under which Fmoc solid phase peptide synthesis may be carried out represents a truly "orthogonal" scheme, and thus offers many unique opportunities for bioorganic chemistry.

Solid phase peptide synthesis utilizing 9‐fluorenylmethoxycarbonyl amino acids

Melanocyte-stimulating hormone (MSH) and adrenocorticotropic hormone (ACTH) regulate pigmentation and adrenal cortical function, respectively. These peptides also have a variety of biological activities in other areas, including the brain, the pituitary, and the immune system. A complete understanding of the biological activities of these hormones requires the isolation and characterization of their corresponding receptors. The murine and human MSH receptors (MSH-Rs) and a human ACTH receptor (ACTH-R) were cloned. These receptors define a subfamily of receptors coupled to guanine nucleotide-binding proteins that may include the cannabinoid receptor.

https://science.sciencemag.org/content/sci/257/5074/1248.full.pdf

The cloning of a family of genes that encode the melanocortin receptors

Tumour necrosis factors, TNF-α and TNF-β (previously called lymphotoxin), are the products of activated monocytes and lymphocytes, respectively, and both have recently been purified, sequenced and cloned by recombinant DNA methods1–5, revealing 35% identity and 50% homology in the amino-acid sequence. Both proteins have been found to be specifically toxic to many tumour cells. Furthermore, it has been reported that various interferons are synergistic with TNF for anti-tumour effects in vitro6–8, while activities attributed to the two proteins have also been shown to necrotize various tumours in vivo2,3,9. We have now prepared 125I-labelled highly purified recombinant human TNF-α to study in detail its binding to the human cervical carcinoma cell line ME-180. Our results indicate that there is a single class of specific high-affinity receptors for TNF on this cell line which has a Kd of about 0.2 nM and an average of 2,000 receptor sites per cell. The binding of labelled TNF-α to these cells can be inhibited by both TNF-α and TNF-β but not by γ-interferon (IFN-γ). However, preincubation of cells with IFN-γ increases the total number of TNF receptors two to threefold without any significant change in the affinity constant. This is the first report that TNF-α and -β share a common receptor and that the receptors can be up-regulated by interferon. Our results may explain previous observations regarding similar biological activities observed for these two cytotoxic proteins and also their synergistic action with interferons.

Characterization of receptors for human tumour necrosis factor and their regulation by γ-interferon

Publisher Summary This chapter discusses the regulation of function in the adrenocortical system. There are three major characteristics that describe most changes in activity of the system: (1) the circadian rhythm in basal activity, (2) stress-induced activation, and (3) corticosteroid feedback regulation. The first two may occur on very different timescales, and it is probably a consequence of the differing temporal demands that the third, corticosteroid feedback inhibition, is exerted by a variety of mechanisms over time. At any time of the day, the adrenocortical system can be activated by application of stressors. These include alteration of the value of a regulated variable or may be invoked by subjecting an animal to sudden disturbances of its environment, for example, noise, flashing lights, handling, strange environment, mild heat or cold. The adrenocortical system may be activated by traumatic stimuli or by psychological stimuli—in man, examinations, or mental arithmetic, or medical school admissions exams; in rats, unexpected decreases in food rewards.

Regulation of ACTH secretion: variations on a theme of B.

Albert Isidro-Llobet, Mercedes Alvarez,* and Fernando Albericio* Institute for Research in Biomedicine, Barcelona Science Park, Baldiri Reixac 10, 08028 Barcelona, Spain; CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Barcelona Science Park, Baldiri Reixac 10, 08028 Barcelona, Spain; Laboratory of Organic Chemistry, Faculty of Pharmacy, University of Barcelona, 08028 Barcelona, Spain; and Department of Organic Chemistry, University of Barcelona, Marti i Franques 1, 08028 Barcelona, Spain Received April 28, 2008

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Amino Acid-Protecting Groups

The binding of corticotropin (ACTH) to receptors on isolated rat adrenocortical cells was investigated with the aid of [[125I]ITyr23, Phe2, Nle4]ACTH-(1-38) (125I-ACTH analog) which retained full biological potency and had a specific radioactivity of 1800 +/- 75 Ci/mmol. Binding was highly specific to adrenocortical cells, and the radioactive peptide was displaced by low concentrations of ACTH but not by other basic peptides. Binding was rapid, reversible, and linearly related to the number of cells. 125I-ACTH analog was not significantly degraded by incubation with the cells at 23 degrees C for 1 hr. Scatchard analysis of the binding was compatible with a single class of binding sites with Kd = 1.41 +/- 0.21 nM, and the number of sites was estimated to be 3840 +/- 1045 per cell. The binding curve was superimposable on the concentration-response curve for cyclic AMP. Small, but significant amounts of 125I-ACTH analog were bound at concentrations sufficient for maximal stimulation of steroidogenesis. For a series of ACTH analogs, the concentrations of the peptides required for half-maximal stimulation of cyclic AMP production were in excellent agreement with the concentration required for half-maximal inhibition of binding. These results suggest that the adrenocortical cells contain only one class of ACTH receptors and that stimulation of a small fraction of these receptors (less than 3%) is sufficient for maximal steroidogenesis.

Characterization of corticotropin receptors on adrenocortical cells

The synthesis of a nonadecapeptide possessing adrenocorticotropic and melanotropic activities

The Synthesis of L-Valyl-L-lysyl-L-valyl-L-tyrosyl-L-proline1

Adrenocorticotropins. XXXIV. Aspects of structure-activity relationships of the ACTH molecule. Synthesis of a heptadecapeptide amide, an octadecapeptide amide, and a nonadecapeptide amide possessing high biological activities

Janakiraman Ramachandran

Papers

Characterization of corticotropin receptors on adrenocortical cells

The synthesis of a nonadecapeptide possessing adrenocorticotropic and melanotropic activities

The Synthesis of L-Valyl-L-lysyl-L-valyl-L-tyrosyl-L-proline1

Adrenocorticotropins. XXXIV. Aspects of structure-activity relationships of the ACTH molecule. Synthesis of a heptadecapeptide amide, an octadecapeptide amide, and a nonadecapeptide amide possessing high biological activities

Preparation of Crystalline NG-Tosylarginine Derivatives1