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Biomedical subjects

A Henschen

Publications and source records attributed to A Henschen.

At least 127 records · Page 7Linked to original sources
PubMed1983

On the structure of functional sites in fibrinogen.

Fibrinogen is involved in many biochemically and medically important processes. In order to obtain a deeper insight into the functional mechanisms of these processes it is necessary to analyse them on the molecular level. The complete covalent structure of human fibrinogen is known, and it is therefore now possible to establish structure-function relationships. For several functional sites the structural equivalent has been well identified, e.g. the thrombin and plasmin cleavage sites, the crosslinking site. For some other sites only the corresponding regions of the molecule are known, e.g. polymerization and calcium-binding sites. However, for many significant physiological functions of fibrinogen the structural basis has not yet been established. On the other hand, there are several regions of the molecule which by evolutionary evidence seem to be of functional importance, but for which no specific functions as yet have been assigned.

Animals↗
PubMed1983

Structural aspects of human kininogens.

Kininogens have been purified from human plasma to apparent homogeneity. Native human LMW kininogen is a single-chain (glyco-) protein of molecular weight 68,000, which is converted to a two-chain protein by limited proteolysis with tissue kallikrein to form a heavy chain (Mr 62,000) and a light chain (Mr 4,000). Human HMW kininogen represents a single chain (glyco-)protein of Mr 114,000 which is split into two chains of similar size (H-chain of Mr 58,000 and L-chain of Mr 62,000) by limited proteolysis with tissue kallikrein. Sequence analysis of the isolated L-chain of human MW kininogen indicates a partial homology to the corresponding fragment-1.2 of bovine HMW kininogen. Purified kininogens readily form self-aggregates ranging from dimer to hexamer (HMW kininogen) and from dimer to decamer (LMW kininogen), respectively. Self-association is completely reversible in the presence of dissociating agents. Preliminary evidence suggests that oligomerisation is mediated by the H-chain common to the two types of kininogens.

Amino Acid Sequence↗
PubMed1982

Potent in vivo and in vitro prolactin inhibiting activity of sauvagine, a frog skin peptide.

The effect of sauvagine (SAU), a frog skin peptide, on prolactin (PRL) levels was studied in vivo and in vitro. Subcutaneous administration of SAU (20 micrograms/kg) reduced plasma PRL levels in normal adult male rats and suppressed the suckling-induced rise of PRL in lactating rats even at doses of 1 and 5 micrograms/kg. Perfusion of isolated and dispersed rat pituitary cells in vitro with increasing doses of SAU (from 5 x 10(-10) to 1.7 x 10(-8)M) induced a significant dose-related decrease of PRL secretion in the eluate. These results indicate that SAU is a potent PRL inhibiting factor and that its action is exerted at the pituitary level. If SAU or a SAU-related peptide is present in the mammalian brain, it can be tentatively hypothesized that this peptide plays an important role in the control of PRL secretion.

Amphibian Proteins↗
PubMed1982

Hemocyanins in spiders, XVII. A presumptive active-site sequence of arthropod hemocyanins.

Peptides containing the sequence -His-His-Trp-His-Trp-His- have been isolated from the subunits e and a of tarantula (Eurypelma californicum) hemocyanin and III B of Limulus polyphemus hemocyanin. In view of the published spectroscopic and titration data on the copper-polypeptide complex and the strong quenching effect of oxygenation on hemocyanin fluorescence, it is concluded that this sequence represents the major part of the active site of Eurypelma, Limulus, and possibly other arthropod hemocyanins.

Amino Acid Sequence↗
PubMed1982

Improved purification and N-terminal amino acid sequence determination of the contact site A glycoprotein of Dictyostelium discoideum.

On aggregating cells of Dictyostelium discoideum a specific glycoprotein is expressed which is absent from growth phase cells of this organism. The glycoprotein has been related to cell surface antigens, called contact sites A, that are defined by their reaction with aggregation blocking antibody fragments. In the present paper an improved purification scheme for the glycoprotein is described and its N-terminal sequence is given. The purification has been monitored by use of a monoclonal antibody. The contact site A glycoprotein has the properties of an integral membrane protein.

Amino Acid Sequence↗
PubMed1981

Amino acid composition and sequence analysis of sauvagine, a new active peptide from the skin of Phyllomedusa sauvagei.

The complete amino acid sequence of sauvagine, a new active polypeptide from the skin of Phyllomedusa sauvagei, a frog of Central and South America, has been determined by automated liquid-phase procedure after specific removal of the N-terminal pyrrolidonecarboxylic acid, and specific cleavages at the single methionine and at the two arginine residues. The proposed sequence is: Pyr-Gly-Pro-Pro-Ile-Ser-Ile-Asp-Leu-Ser-Leu-Glu-Leu-Leu-Arg-Lys-Met-Ile-Glu-Ile -Glu-Lys-Gln-Glu-Lys-Glu-Lys-Gln-Gln-Ala-Ala-Asn-Asn-Arg-Leu-Leu-Leu-Asp-Thr-Il e-NH2. Sauvagine possesses a number of pharmacological actions on diuresis, the cardiovascular system and endocrine glands; it can be considered the prototype of a new family of amphibian peptides, in addition to the tachykinins, bradykinins, dermorphins, caerulein-like and bombesin-like peptides.

Amino Acid Sequence↗
PubMed1981

Analysis of human fibrinopeptides by high-performance liquid chromatography.

During coagulation, fibrinogen is cleaved by thrombin, whereby fibrin and low molecular mass peptides, the so-called fibrinopeptides, are released. A novel method, employing high-performance liquid chromatography, has been developed for the separation and quantitation of these peptides. For the chromatography a reversed phase column was used. The fibrinopeptides were detected by their UV-absorption at 210 nm, peptides released from 0.1 mg of fibrinogen being easily detected. The procedure offers for the first time the possibility of determining all human fibrinopeptides and their degradation products in a single analysis. It is eminently suited for fibrinopeptide preparation and studies of fibrinopeptide release kinetics and genetically abnormal fibrinopeptides.

Chromatography, High Pressure Liquid↗
PubMed1980

Nature and extent of peptide bond cleavage by anhydrous heptafluorobutyric acid during Edman degradation.

It is well established that during the isothiocyanate degradation of proteins a gradual increase of the level of all thiohydantoin derivatives of amino acids occurs, which progressively obscures the sequential identification of the significant N-terminal amino acids. The major cause for this has been shown to be due to a hitherto unknown specific cleavage at aspartic acid residues in anhydrous heptafluorobutyric acid and to a lesser extent, the N leads to O shift in peptide bonds involving hydroxyamino acids. Measures to reduce the susceptibility of the peptide bonds at these sites are described.

Amino Acid Sequence↗
PubMed1980

Hemocyanins in spiders, X. Limited proteolysis of chain e of Eurypelma hemocyanin and partial sequence of two large fragments.

The polypeptide chain e of the homocyanin from the spider Eurypelma californicum was isolated by ion exchange chromatography. Incubation of the undenatured protein with chymotrypsin, subtilisin, or trypsin resulted in a small number of large fragments which were easily isolated after denaturation. Of the chymotryptic peptides e-Chn-29 was found to be N-terminal, and e-Chn-42 C-terminal. These peptides were characterized by their N-terminal amino acid sequences. The N-terminal sequence of subunit e shows homologies with other arthropod hemocyanins.

Amino Acid Sequence↗
PubMed1980

N-Terminal amino acid sequence of boar sperm acrosin. Homology with other serine proteinases.

Boar acrosin with a molecular weight of 38,000 had been isolated. An N-terminal amino acid sequence of 52 residues was determined on the S-carboxymethylated material. The protein contains a single peptide chain. Up to 48% of the positions in the sequence show identity with those of some serine proteinases. The highest degree of homology was found at the comparison with plasmin and chymotrypsin. The N-terminus of acrosin corresponds to that of a serine proteinase in the activated form. The N-terminal amino acid is valine.

Acrosin↗