Biosynthesis of a D-amino acid in peptide linkage by an enzyme from frog skin secretions

Proceedings of the National Academy of Sciences (2005)

Alexander Jilek Christa Mollay Christa Tippelt Jacques Grassi Giuseppina Mignogna Johannes Müllegger Veronika Sander Christine Fehrer Donatella Barra Günther Kreil

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Abstract:

d -amino acids are present in some peptides from amphibian skin. These residues are derived from the corresponding l -amino acids present in the respective precursors. From skin secretions of Bombinae , we have isolated an enzyme that catalyzes the isomerization of an l -Ile in position 2 of a model peptide to d -allo-Ile. In the course of this reaction, which proceeds without the addition of a cofactor, radioactivity from tritiated water is incorporated into the second position of the product. The amino acid sequence of this isomerase could be deduced from cloned cDNA and genomic DNA. After expression of this cDNA in oocytes of Xenopus laevis , isomerase activity could be detected. Polypeptides related to the frog skin enzyme are present in several vertebrate species, including humans.

Keywords:

Frog Skin

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Amino Acid Enzymes and Metabolism

Chemical Synthesis and Analysis

Enzyme Structure and Function

10.1073/pnas.0500789102

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Immunohistochemical Localization of Calpains in the Amphibian Xenopus laevis

Methods in molecular biology (2019)

Jean‐Marie Exbrayat Elara Moudilou Claire Brun

Immunofluorescence

10.1007/978-1-4939-8988-1_7

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Peptidomic analysis of skin secretions provides insight into the taxonomic status of the African clawed frogs Xenopus victorianus and Xenopus laevis sudanensis (Pipidae)

Comparative Biochemistry and Physiology Part D Genomics and Proteomics (2013)

Jay D. King Milena Mechkarska Mohammed A. Meetani J. Michael Conlon

Magainin

African clawed frog

Frog Skin

10.1016/j.cbd.2013.07.001

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Autoradiographic localization of hormone‐concentrating cells in the brain of an amphibian, Xenopus laevis. II. Estradiol

The Journal of Comparative Neurology (1975)

Joan I. Morrell Darcy B. Kelley Donald W. Pfaff

Abstract Autoradiographic techniques for light microscopic examination of sex steroid retention were applied to the brains of male and female Xenopus laevis , an anuran amphibian, after 3 H‐estradiol administration. Estrogen was concentrated by cells in three telencephalic areas (the ventral striatum, the ventral‐lateral septum and the amygdala), the anterior preoptic area, the ventral thalamus, the ventral infundibular nucleus, and in the torus semicircularis. The anterior preoptic area and the ventral infundibular nucleus contained the greatest number of labelled cells. The topography of estrogen‐concentrating cells was the same in male and female brains. This fact and comparisons of 3 H‐estradiol with 3 H‐testosterone retention in Xenopus suggest that the sex steroid itself, and not the genetic sex of Xenopus determines the pattern of uptake by cells in the brain. The distribution of hormone‐concentrating cells in Xenopus has many similarities to that found in birds and mammals. Preoptic, hypothalamic (tuberal), limbic forebrain and specific mesencephalic sites in all these forms contain labelled cells following radioactive sex steroid administration. Findings in Xenopus add to the argument for a phylogenetically stable system of hormone‐concentrating nerve cells in limbic, hypothalamic and mesencephalic structures.

Preoptic area

Limbic system

Forebrain

10.1002/cne.901640106

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Bombesin-Like Peptide Genes

Humana Press eBooks (1987)

Eliot R. Spindel

Bombesin, a tetradecapeptide, was first isolated from the skin of the frog Bombina bombina by Anastasi and coworkers in 1971 (1). Subsequently, related peptides were found in the skin of other amphibian species (2–4). After it was isolated, bombesin was found to have marked biological activity despite the fact that no mammalian counterpart was known. Synthetic amphibian bombesin released gastrointestinal (GI) hormones (2, 5, 6), stimulated gastric motility (6), and, when injected into the brain, produced hypothermia (7).

Frog Skin

10.1007/978-1-4612-4824-8_15

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IMMUNOLOGICAL TOLERANCE IN THE AMPHIBIAN XENOPUS LAEVIS (DAUDIN)

Esme Kila Farley

African clawed frog

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PH-sauvagine from the skin secretion of Phyllomedusa hypochondrialis: A novel CRF-like peptide with smooth muscle contraction activity

Toxicon (2015)