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R Acher

Publications and source records attributed to R Acher.

At least 91 records · Page 5Linked to original sources
PubMed1981

Phylogeny of neurohypophyseal hormones. Vasopressin polymorphism in three kangaroo species.

The neurohypophyseal hormones of three species of Australian marsupials belonging to the family Macropodidae (Macropus rufus, Macropus giganteus, Macropus robustus) have been investigated. In these species three active peptides have been disclosed, one with oxytocic activity and two with pressor activity. The three hormones are present in all the individual glands which have been examined. Purification has been undertaken by ion-exchange chromatography and paper chromatoelectrophoresis. The more abundant of the pressor hormones (about 80% of the total pressor activity) has been identified as lysine-vasopressin by its biological properties, its chromatographic behaviour and its amino acid composition. The second pressor principle, more basic, has not yet been chemically characterized but its pharmacological properties and its chromatographic behaviour suggest that it is closely related or identical to arginine-vasopressin. Dimorphism of vasopressins seems peculiar to Metatheria since it has not been observed in Protheria and very rarely in Eutheria.

Amino Acid Sequence↗
PubMed1980

Phenypressin (Phe2-Arg8-vasopressin), a new neurohypophysial peptide found in marsupials.

Recent investigations on marsupial neurohypophysial hormones have revealed that species belonging to the Australian family Macropodidae and the American family Didelphidae have, apart from an oxytocin-like hormone, two vasopressin-like peptides which can be separated either by ion-exchange chromatography or chromatoelectrophoresis. The major pressor hormone of two Australian species, the red kangaroo (Macropus rufus) and the tammar (Macropus eugenii), has been identified as lysine vasopressin by its amino acid sequence anda its pharmacological properties. We report here that the minor pressor hormone, which chromatographs on Amberlite CG-50 like arginine vasopressin, differs from it in sequence only at position 2 where phenylalanine replaces the tyrosine of arginine vasopressin.

Amino Acid Sequence↗
PubMed1980

[Evolution of vasopressins in marsupials: a new hormone, phenypressin (Phe2-Arg8-vasopressin), present in the Macropodidae].

A duplication of the pressor hormone has been found in some marsupials, either American species belonging to the family Didelphidae or Australian species belonging to the family Macropodidae. Two pressor peptides, lysine vasopressin and phenypressin (Phe2-Arg8-vasopressin) have been chemically identified in the red Kangaroo (Macropus rufus) and the Tammar (Macropus eugenii). In contrast, the brush-tailed Possum (Trichosurus vulpecula), a species belonging to the family Phalangeridae, has a single pressor hormone, arginine vasopressin. Because this latter hormone was also found in a prototherian species, the Echidna, it might be assumed that it is the product of a primitive gene and that a duplication and subsequent mutations led to lysine vasopressin and phenypressin in Macropodidae.

Animals↗
PubMed1976

Molecular evolution of the polypeptide hormones.

Any biological function is at least bimolecular and its evolution therefore is at least dual, with variations in two lines of molecules. The hormone specificity results from a particular fit between the three-dimensional structure of the agent and that of the receptor but, because receptors are not known at the structural level, a discussion on the evolution of the polypeptide hormones is mainly limited to the possible progressive changes of the latter. As for other proteins (enzymes, oxygen carriers etc.) two degrees of complexity can be distinguished according to whether the hormone comprises one or several polypeptide chains. Protein assembly can bring new biological properties, each subunit playing a particular role. In this case, the 'internal' evolution (chain-chain interactions) overlaps the 'external' evolution (hormone-receptor contacts). The 'monomeric' hormones present the following problems: evolution of the prohormone and of the converting enzyme (for insulin), duplication and differentiation of two lines of hormones either by amino acid substitutions (neurohypophysial hormones and neurophysins) or by substitutions and size modifications (corticotropin and lipotropin), duplication and fusion leading to internal homology in the single polypeptide chain (somatotropin, prolactin, placental lactogen). The 'dimeric' hormones lead to several problems: successive duplications giving different subunits, selective associations between subunits, unequal rates of evolution of the subunits, the function of each subunit (lutropin, follitropin, thyrotropin, choriogonadotropin). An attempt is made to integrate the evolution of polypeptide hormones in the frame of the evolution of proteins.

Amino Acid Sequence↗