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Biomedical subjects

H Scheer

Publications and source records attributed to H Scheer.

46 records · Page 3Linked to original sources
PubMed1977

Studies on plant bile pigments, II[1]. Chemical and photochemical oxygenation of a phytochrome Pr chromophore model pigment to purpurins.

The chemical and photochemical oxygenation of 2,3-dihydrooctaethyl-1,19(21,24H)-bilindione (1), as a model for the chromophores of both phytochrome Pr and phycocyanin, has been studied in neutral and alkaline solution, and in the presence of zinc ions. By comparison with octaethyl-1,19(21,24H)-bilindione (5), the influence of ring A hydrogenation on the reactivity of bilins has been assessed. In the dark, 1 is attacked selectively and rapidly at C-5 yielding "purpurins", while 5 reacts slowly, and is attacked predominantly at C-10. Photooxidation of 5 yields the tripyrrinic "purpurin" 7 only. Photoreactivity of 1 is considerably enhanced, yielding "purpurins" and "violins" rapidly. In spite of UV-vis and mass spectroscopic similarities, the "purpurin" 7 differs from the "purpurins" 6a,b by the loss of ring A. The facile cleavage at the C-5 methine bridge and the spectroscopic properties of "purpurins" are discussed.

Models, Chemical↗
PubMed1977

[Short-term catheterization following electroresection of the prostate and adenomectomy].

The catheter short-term treatment is used in altogether 500 patients in adenectomy as well as in TUR. Apart from the restoration of regular passage the reduction of the infection of the urinary tract is the most important aim of the surgery of the prostate gland. With the help of the short catheter follow-up treatment within the first four weeks after operation the infection of the urinary tract is cured in 87,5% of the cases. The subjective trouble of the patient is further decreased. Prerequisite for the permanent catheter short-term treatment is the exact operation technique combined with most careful haemostasis.

Electrosurgery↗
PubMedDate not supplied

Chemical modification of biliprotein chromophores.

The reaction of biliproteins with sodium dithionite has been studied. The reagent is selective towards the chromophores. In denatured phycocyanin from Spirulina platensis, all three chromophores react to form yellow "phycorubin", whereas only 1/3 of the chromophores react in native phycocyanin in a non-statistical manner. From reversion experiments, it can be shown, that the thermodynamic stability of the chromophores towards reaction with dithionite is increased in the native pigment. Similarly, native phytochrome in its Pr form reacts only partially to a pigment absorbing at both 420 and 660 nm. The same product is formed from native Pfr, indicating both a reversion to Pr and a partial reduction.

Dithionite↗
PubMedDate not supplied

Reconstitution of an allophycocyanin trimer complex containing the C-terminal 21-23 kDa domain of the core-membrane linker polypeptide Lcm.

Allophycocyanin (AP) was isolated from extracts of the cyanobacterium Mastigocladus laminosus. A fraction enriched in AP-associated polypeptides with apparent molecular masses of 21-23 kDa in SDS-PAGE, was isolated on a preparative scale and identified as a homologous mixture of C-terminal fragments of the core-membrane linker polypeptide Lcm. The complex (alpha AP beta AP)3.21-23 kDa was reconstituted and characterized by sucrose density gradient ultracentrifugation, absorption, fluorescence emission and circular dichroism spectroscopy. The 21-23 kDa polypeptides were found to induce spectral changes in AP similar to those induced by the small core linker polypeptide Lc8.9. Possible functions of the complex in phycobilisomes are discussed.

Amino Acid Sequence↗