Correlation between processing efficiency for ribonuclease P minimal substrates and conformation of the nucleotide -1 at the cleavage position.

It is demonstrated that acceptor stem duplexes derived from native tRNAs which contain a three-nucleotide extension at the 5'-terminus of mature tRNA are minimal substrates for ribonuclease P from both Escherichia coli and Bacillus subtilis. Variants with a cytidine at position -1 are most efficiently processed whereas the G -1 variant represents a comparatively poor substrate. An A -1 acceptor stem variant is a slightly better substrate than the G -1 variant though generally distinctly less efficient than the C -1 duplex. This is in qualitative agreement with the frequency of the occurrence of the corresponding nucleotides at position -1 in natural substrates, which is highest for pyrimidines and least for G. NMR analyses of the corresponding acceptor stems reveal that the conformation of the nucleotides at position -1 correlates with the substrate preferences of Ribonuclease P: Whereas C -1 adopts a conformation characterized by a glycosidic angle in the anti range (close to high-anti), the G -1 is clearly in syn conformation, and that of A -1 is intermediate between high-anti and syn. The riboses of nucleotides -1 are in all cases predominantly 2'-endo puckered.

The C-A mismatch base pair and the single-strand terminus in the E. coli initiator tRNA(fMet) acceptor stem adopt unusual conformations.

Acceptor stem variants of tRNA(fMet) (Escherichia coli) have been characterized by nuclear magnetic resonance. The wild type contains a C1-A72 mismatch pair which is crucial for its biological function. For comparison, the mismatch was replaced by regular pairs U1-A72 and C1-G72. Further variants contain an altered discriminator base, G73, or a G1-C72/U73 combination. The stems of variants U1-A72/A73 and C1-G72/A73 have A-RNA geometry, which extends essentially to the single-strand terminus. C1-A72/G73 variant and wild type are structurally almost identical. C1 and A72 adopt peculiar conformations with C1 being largely destacked with respect to G2, while A73 stacks upon C1. The unique arrangement of the mismatch causes a distinctly different orientation of the single-strand terminus compared to variants with regular 1-72 base pairs, and to formyltransferase-complexed tRNA(fMet).

Crystal structure of acceptor stem of tRNA(Ala) from Escherichia coli shows unique G.U wobble base pair at 1.16 A resolution.

The acceptor stem of Escherichia coli tRNA(Ala), rGGGGCUA.rUAGCUCC (ALAwt), contains the main identity element for the correct aminoacylation by the alanyl tRNA synthetase. The presence of a G3.U70 wobble base pair is essential for the specificity of this reaction, but there is a debate whether direct minor-groove contact with the 2-amino group of G3 or a distortion of the acceptor stem induced by the wobble pair is the critical feature recognized by the synthetase. We here report the structure analysis of ALAwt at near-atomic resolution using twinned crystals. The crystal lattice is stabilized by a novel strontium binding motif between two cis-diolic O3'-terminal riboses. The two independent molecules in the asymmetric unit of the crystal show overall A-RNA geometry. A comparison with the crystal structure of the G3-C70 mutant of the acceptor stem (ALA(C70)) determined at 1.4 A exhibits a modulation in ALAwt of helical twist and slide due to the wobble base pair, but no recognizable distortion of the helix fragment distant from the wobble base pair. We suggest that a highly conserved hydration pattern in both grooves around the G3.U70 wobble base pair may be functionally significant.

Structural and dynamic helix geometry alterations induced by mismatch base pairs in double-helical RNA.

A ribooligonucleotide microhelix derived from the acceptor stem of Escherichia coli tRNA(Ala) having a C3-A70 mismatch in place of the G3-U70 wobble pair in the wild-type tRNA(Ala), and a sequence variant with a regular U3-A70 base pair have been investigated by NMR. In vivo, suppressor tRNA(Ala) variants with C3-A70 (as well as several other) mismatch pairs are substrates for alanyl-tRNA synthetase (ARS), supporting the hypothesis of an 'indirect' recognition of the identity element 3-70 mismatch pair via structural modifications caused by the mispair in comparison to canonical A-RNA helices. It is demonstrated that the C-A mismatch likewise induces helix geometry alterations, in particular with respect to base stacking in the vicinity of the mismatch. However, with reference to the 'wild-type' G3-U70 microhelix, destacking in the C3-A70 acceptor stem duplex occurs in the opposite direction from the mismatch pair. Therefore it is concluded that the locally enhanced conformational flexibility or dynamics associated with the structural changes induced by the mismatch pairs could be an essential prerequisite for optimal adaptation of the tRNA(Ala) acceptor stem to the contact region of the ARS.

[Multicenter study of obstetrico-perinatologic quality control in the Rostock district. I. Comparative medical statistics]. / Multicenterstudie zur geburtshilflich-perinatologischen Qualitätskontrolle im Bezirk Rostock. I. Mitteilung: Vergleichende Medizinalstatistik.

Report about outcome-quality assessment in obstetrics and perinatology using an uniform check list for data collection in the district of Rostock. Various possibilities of outprint of the results in 1985 are demonstrated. For daily data collection in obstetrics a special book has been developed. The investigation concerns a data pool of more than 55,000 deliveries. Considering a trend of the results the following optimal criteria in obstetrics and perinatology are postulated: (table; see text) The check list of the Society of Perinatal Medicine of the GDR for obstetrical and neonatal data collection should be generally used. The soft ware for the computed data analyses has been developed by the "Rechenzentrum der Ernst-Moritz-Arndt-Universität Greifswald". Analysis and output of obstetrical and perinatological datas by means of a personal computer are prepared.

Novel glucoalkaloids from Rauwolfia cell cultures--acetylrauglucine and related glucosides.

From cell suspension cultures of Rauwolfia serpentina grown in an optimized production medium for the glucoalkaloid raucaffricine, a novel glucoalkaloid was isolated and identified as 17-O-acetyl-21-O-beta-D-glucopyranosyl-ajmaline (acetylrauglucine). This alkaloid is formed in very small amounts (less than 5 x 10(-4)%). The biogenetically related N alpha-demethylated base (acetyl-nor-rauglucine) and the deacetyl product rauglucine have also been detected in culture extracts. In addition 21(R)-(beta-D-glucopyranosyl)-hydroxy-sarpagan-17-al has been isolated and identified as an artifact which originates from raucaffricine.

Characterization of 2 beta (R)-17-O-acetylajmalan: acetylesterase--a specific enzyme involved in the biosynthesis of the Rauwolfia alkaloid ajmaline.

A novel enzyme was isolated, partially purified (217-fold) and characterized from cell suspension cultures of Rauwolfia serpentina Benth. The enzyme catalyzes one of the late biochemical reactions in the biosynthesis of ajmaline by hydrolysis of 17-O-acetylated alkaloids of the ajmalan group forming the appropriate deacetylated compounds. This esterase exhibits an unusually high substrate selectivity and exclusively accepts acetylated ajmaline derivatives with the naturally occurring 2 beta (R)-configuration. The properties of the enzyme were determined showing an optimum pH at 7.5, an isoelectric point of pH 4.9 and a relative molecular weight of 33 +/- 2 kDa. Inhibition studies of enzyme activity point to the necessity of SH-groups. The esterase seems not to be inhibited by ajmaline, the end product of the pathway. The highest enzyme activities were observed in leaves and cell suspension tissues of the tribe Rauwolfieae which are known to synthesize ajmaline and its congeners. The specific function of the esterase in the biosynthesis of the later alkaloids was established.

RLCC-isolation of Raucaffricine from its most efficient source - cell suspension cultures of Rauwolfia serpentina Benth.

Raucaffricine (vomilenine-galactoside) was shown to be the major indole alkaloid of Rauwolfia serpentina Benth. cell suspension cultures grown in AP-medium (alkaloid production medium). Several grams of this glycoalkaloid can conveniently be isolated by RLCC (Rotation Locular Countercurrent Chromatography). A newly discovered enzyme efficiently converts the glycoalkaloid to its aglycon, vomilenine, which occupies a key function in the biosynthesis of ajmaline. This is the first demonstration of the occurrence of raucaffricine in Rauwolfia serpentina.

[Primary genital actinomycosis of women (author's transl)]. / Zur primären Genital-Aktinoimykose der Frau.

PIP: Reported in this paper are 8 histologically secured cases of primary actinomycosis of the female genital tract in IUD users. Reference is made to the potential relationship between IUD use and genital actinomycosis. Reference is also made to the most recent literature in an attempt to describe the route of infection, pathogenesis, and clinical aspects, with particular emphasis placed on differential diagnosis and therapy. (author's modified)^ieng

[Clinical and exfoliative-cytology studies made prior and subsequent to the action of antiovulatory agents upon oral and vaginal mucous membranes (author's transl)]. / Klinische und exfoliativzytologische Untersuchungen vor und nach der Einwirkung von Kontrazeptiva auf die orale und vaginale Schleimhaut.

Clinical as well as oro- and vaginocytological results obtained from 92 female patients aged 16 to 48, to whom ovulostatic drugs were administered, have been analyzed. Variations in cell composition of the mucosal surface could be detected by exfoliative cytology in the vaginal and oral regions.