Structure-property relationship of anilino-squaraines in organic solar cells.

Soluble molecular semiconductors are a promising alternative to semiconducting polymers in the field of organic photovoltaics. Here, three custom-made symmetric 1,3-bis(N,N-alkylated-2,6-dihydroxy-anilino)squaraines containing systematic variations in their molecular structures are compared regarding their applicability as donor materials in bulk-heterojunction solar cells. The terminal substitution pattern of the squaraines is varied from cyclic over linear to branched including a stereogenic center. Single crystal structures are determined, and, in the case of chiral squaraine, unusual formation of stereoisomer co-crystals is revealed. The thin film absorbance spectra show characteristic signatures of H- and J-bands or hint at the formation of tautomers. The general feasibility of these model compounds for photovoltaic applications is studied by light-induced electron spin resonance spectroscopy. The impact of the different molecular substitution patterns on aggregation behavior and, consequently, their optoelectronic solid state properties including charge carrier mobility and finally the solar cell performance are investigated.

Treatment of testicular intraepithelial neoplasia (intratubular germ cell neoplasia unspecified) with local radiotherapy or with platinum-based chemotherapy: a survey of the German Testicular Cancer Study Group.

BACKGROUND: The treatment of testicular intraepithelial neoplasia (TIN), the progenitor of testicular germ cell tumours (GCTs), is based on little data. PATIENTS AND METHODS: Two hundred and twenty-eight GCT patients with contralateral TIN were retrospectively enrolled. Ten had surveillance, 122 radiotherapy to testis with 18-20 Gy, 30 cisplatin-based chemotherapy (two cycles), 51 chemotherapy (three cycles), and 15 carboplatin. The study end point was a malignant event (ME), defined as detection of TIN upon control biopsy or occurrence of a second GCT. The Secondary end point was hypogonadism during follow-up. RESULTS: Numbers, proportions of ME, and median event-free survival (EFS) times were: radiotherapy N = 3, 2.5%, 11.08 years; chemotherapy (two cycles) N = 15, 50%, 3.0 years; chemotherapy (three cycles) N = 12, 23.5%, 9.83 years; carboplatin N = 10, 66%, 0.9 years; surveillance N = 5, 50%, 7.08 years. EFS is significantly different among the groups. Hypogonadism rates were in radiotherapy patients 30.8%, chemotherapy (two cycles) 13%, chemotherapy (three cycles) 17.8%, carboplatin 40%, surveillance 40%. CONCLUSIONS: Local radiotherapy is highly efficacious in curing TIN. Chemotherapy is significantly less effective and the cure rates are dose-dependent. Though hypogonadism occurs in one-third of patients, radiotherapy with 20 Gy remains the standard management of TIN.

Characterization of site-directed mutations in conserved domains of MalK, a bacterial member of the ATP-binding cassette (ABC) family [corrected].

Site-directed mutagenesis was used to change four amino acid residues (Q82, P152, L179, H192) in the MalK subunit of S. typhimurium maltose transport system which are highly conserved among members of the ATP-binding cassette (ABC) family. Replacement of H192 caused complete failure to complement the transport defect of a malK strain whereas changes of the other residues resulted in reduced or wild-type activity. The purified mutant proteins exhibited ATPase activity comparable to wild-type MalK.

Nucleotide-induced conformational changes of MalK, a bacterial ATP binding cassette transporter protein.

Nucleotide-induced structural rearrangements of MalK, the ATP-hydrolyzing component of the ATP binding cassette transporter for maltose from Salmonella typhimurium were investigated by means of analysis of intrinsic tryptophan fluorescence and limited proteolysis. ATP was found to decrease the tryptophan fluorescence of purified MalK by 37 +/- 1%. ADP or adenosine 5'-O-(3-(thio)triphosphate) (ATP gamma S) caused similar quenching while AMP was rather ineffective. Mg2+ ions were not required. Exposure of MalK to increasing concentrations of trypsin and subsequent analysis by SDS-polyacrylamide gel electrophoresis and immunoblotting revealed the formation of three major transiently stable peptide fragments of 24 (T2), 23 (T3), and 20 kDa (T4), respectively. In addition, a minor rapidly degraded fragment of 33 kDa (T1) was observed. However, in the presence of MgATP, fragment T1 as well as a substantial fraction of native MalK were strongly protected against proteolytic attack. Similar protection against the protease was observed in the presence of MgGTP or, to a lesser extent, MgCTP. In contrast, MgADP, ATP in the presence of EDTA, CaATP or nonhydrolyzable nucleotides such as MgATP gamma S or MgAMP-PNP (beta, gamma-imidoadenosine-5'-triphosphate) failed to significantly affect the susceptibility of MalK to the protease. MgATP similarly affected the tryptic digestion pattern of a mutant protein (MalKK42R) that exhibits only a much reduced ATPase activity but has retained the capability to bind nucleotides. N-terminal protein sequence analysis of the peptides revealed cleavage by trypsin at Arg66 (T1), Arg146 (T2), Arg153 (T3), and Arg185 (T4), respectively. These results indicate that (i) nucleotide binding to MalK is accompanied by a global conformational change of the protein; (ii) a very specific interaction occurs with substrates of the MalK-ATPase, resulting in structural changes that involve the helical domain from Arg66 to Arg146; and (iii) the C-terminal half of MalK is rather resistant to proteolysis.

A putative helical domain in the MalK subunit of the ATP-binding-cassette transport system for maltose of Salmonella typhimurium (MalFGK2) is crucial for interaction with MalF and MalG. A study using the LacK protein of Agrobacterium radiobacter as a tool.

The ATP-binding-cassette (ABC) protein LacK of Agrobacterium radiobacter displays high sequence similarity to the MalK subunit of the Salmonella typhimurium maltose-transport system (MalFGK2). We have used LacK as a tool to identify sites of interaction of MalK with the membrane-integral components MalF and MalG. Small amounts of LacK, resulting from the expression of the plasmid-borne lacK gene, proved to be sufficient for partial restoration of growth of a malK strain of S. typhimurium on maltose. LacK failed to substitute for MalK in regulating the expression of maltose-inducible genes but the hybrid complex MalFGLacK2 was sensitive to inducer exclusion. The lacK gene also complemented a ugpC mutant of Escherichia coli to growth on sn-glycerol-3-phosphate as the phosphate source. Partially purified LacK exhibited a spontaneous ATPase activity comparable to that of MalK. A MalK"-'LacK chimeric protein was isolated (by in vivo recombination) in which the N-terminal 140 amino acids of MalK are fused to residues 141-363 of LacK. The protein substituted for MalK in maltose transport considerably better than LacK. Furthermore, random mutagenesis of the plasmid-borne lacK gene yielded three clones that were superior to wild-type lacK in complementing a malK mutation. Single mutations (V114M or L123F) substantially improved the growth of a malK strain on maltose, whereas a double mutation (L123F, S295N) resulted in growth and transport rates that were indistinguishable from those obtained with MalK. In contrast, the introduction of the single change S295N into LacK had no effect but combination with the V114M mutation led to a further twofold increase in transport activity. These results indicate that a putative helical domain in MalK, encompassing residues 89-140, is crucial for a functional, high-affinity interaction with MalF and MalG.