M. Wiewiórowski

Organization of ribosomal DNA in yellow lupine (Lupinus luteus) and sequence of the 5.8 S RNA gene

The large ribosomal repeat of the Lupinus luteus genome is 8.8 kb in length as revealed by Southern blotting and hybridization to 5.8 S rRNA and cloned rDNA fragments of L. luteus and Schizosaccharomyces pombe. It codes for 18 S,5.8 S and 28 S rRNAs. A cloned 3.7 kb EcoR1 subfragment of the rDNA repeat, coding for 5.8 S rRNA and a large portion of the 28 S rRNA, has been sequenced in the region of 5.8 rRNA gene. The predicted rRNA sequence is homologous to broad bean 5.8 S rRNA and can be arranged in the generalized model of 5.8 S RNA secondary structure.

Purification and properties of methionyl-tRNA-synthetase from yellow lupine seeds

In many euca~~tic org~isms studied so far there are two rne~iQ~e.~~~i~c tRNAs: initiator (tRNAy ) and non-initiator (tRNAr). The primary structures of several taco have been elucidated and the e~ste~~e of their great similarities ~tab~~ed_ Roth tRNAfet are recognized by the same rne~ouy~tRNA ~ntheta~ @ietRS, EC 6.l.l.lO) [l--3]. Purification and properties of MetRS from wheat germ have been published and differences haw; appeared [4-61. In our studies on plant tRNA and aminoacyltRNA synthetases we have isolated tRNA?t and MetRS from yellow Iupine seeds. In work on rne~on~e-tRNA hgase we have found some interesting obse~a~ons ~o~~e~~g pu~~~tio~ and properties of this enzyme. The procedure for isolator consists of the ~~5~~~1 s~~hate fractionation, gel f&ration on Sephadex G-150, DEAEcellulose, DEAE-Sephadex A-50, Sephadex G-ZOO filtration and phosphocellulose column chromatography, We have obt~Ed a 545-fold puri~cation of the enzyme with the recavery of over 1.6% activity applied In the first step. Polyacryhunide gel electrophoresis and gel fdtration method showed mol, wt 170 000, The yeflow lupine MetRS has two subunits and the results took similar to those obtained for wheat germ /4,5] but different from [6] _

Conservation of the structures of plant tRNAs and aminoacyl-tRNA synthetases

Since the determmatlon of the first nucleotlde sequence of a transfer rlbonuclelc acid (tRNAAh) in 1965 [l], almost 200 primary structures of other tRNAs have been determined [2,3] Among them tRNAs specific for phenylalanme and methlonme are of most interest The former for their easy punticatlon by benzoylated DEAE-cellulose column chromatography [4] and the latter m respect to their special functions m protein biosynthesis [5]. Both tRNAs were Isolated from different sources [6] and some slmllarltles appeared At the same time many ammoacyl-tRNA synthetases from different orgamsms were punfied and some generahsatjons concerning their structures have been formulated [7,8]. Among large number of organisms from which tRNAs and synthetases were characterized,, higher plant material was little studied, one reason being difficulty m preparation of sufficient quantities of these macromolecules m the pure state [9,10] As far as tRNA 1s concerned, phenylalanme specific tRNA was sequenced from wheat germ [ 111, pea [ 121, yellow lupm [ 131 and barley [ 141 Methlonme mltlator tRNA structure was determined for wheat germ [ I.51 and tentatively, yellow lupine seeds [ 161 Ammoacyl-tRNA synthetases (AARS) charging cognate tRNA with phenylalanme (PheRS), methlonme (MetRS), argimne (ArgRS) and leucme (LeuRS) from wheat germ [ 17-191 and yellow lupm seeds [3-O-22] were characterized. The purpose of this work 1s to compare and analyse the sumlarltles and differences m the structures of

The nature of drastic differences in the recognition of protonated cytidinium and deoxycytidinium cations by their parent nucleosides within dihydrogenphosphate salts in the light of the computer-simulated crystal structure of dCyd hemiphosphate (dCyd)2H+ H2PO−*4

Abstract In the crystal structures of cytidine (Cyd), deoxycytidine (dCyd) and their dihydrogen phosphates, we have found important information about their abilities to resist transformation in the solid phase. On this basis we predicted and realised the transformation of the monophosphate into the hemiphosphate of dCyd and vice versa [dCydH + H 2 PO − 4 ⇌ (dCyd) 2 H + H 2 PO − 4 ], and simulated the latter structure by computer modelling of the former. We also discuss the molecular mechanism of both transformations in which protonation and deprotonation processes play leading roles. In the light of observations accumulated in this paper, further progress in the crystal engineering of nucleosides appears to be promising.

Some new examples of very strong hydrogen bonds at inversion point. Molecular and crystal structure of hydrochlorides of N-methylpiperidin-2-one, and quinolizidin-4-one

Abstract The structures of the cations derived from the simplest and most common mono- and bicyclic delta lactams, i.e. N -methylpiperidin-2-one and quinolizid-4-one, and simple acids are discussed on the basis of spectroscopic and X-ray structural data. In addition to these tertiary lactam salts, the structure of the simplest secondary delta lactam salt, piperidin-2-one hydrochloride, is also discussed and compared with caprolactam hydrochloride.

The stereochemistry of quaternary N-methyl sparteinium cations, their derivatives, stereoisomers and analogues: Part II. Molecular and crystal structure, and IR spectra of methiodide and methperchlorate of 2-oxosparteine

Abstract The crystal and molecular structures of two quarternary salts of 2-oxosparteine (II), the methiodide (IICH + 3 • I − ) and the methperchlorate (IICH + 3 • ClO − 4 ) have been determined on the basis of X-ray and IR data. The studies were performed by analogy to previously investigated quaternary salts of sparteine (I), the methiodide (ICH + 3 • I − ) and the methperchlorate (ICH + 3 • ClO − 4 ). As expected, the configurations and conformations of cationic parts within the two pairs of quaternary salts are identical, except for the structure of their A/B fragments, which in ICH + 3 cations have the character of tertiary amines, but in IICH + 3 that of lactams. On the basis of accumulated X-ray and IR data the similarities and differences in the modes of interaction of perchlorate and iodide anions with quaternary cations, and especially with their N + CH 3 groups are discussed. In this discussion are also included the methiodide and methperchlorate of α-isosparteine: IIICH + 3 • X − (X − = I − or ClO − 4 ) where N + CH 3 groups are cisoidally oriented to the basic nitrogen atoms. The most interesting observations are as follows: (i) When N + CH 3 groups are easily accessible for direct quasi hydrogen bonding interactions with counter anions and when other positive charged groups, for instance lactam groups, are absent in quaternary cations, perchlorate anions interact more strongly than the iodide anions and in consequence introduce conformational changes into the ring with N + CH 3 group as well as into further rings. (ii) Perchlorate and iodide anions interact with N + CH 3 groups similarly and very weakly if at all, when the N + CH 3 groups are for steric reasons inaccessible to counter anions or when in quaternary cations there are additional groups which attract the counter anions electrostatically. The last mechanism operates in both quaternary salts of 2-oxosparteine and this is the reason why their monocrystals are isosteric and IR spectra almost identical. (iii) The sterically hindered N + CD 3 groups in both IIICD + 3 • X − salts give rise in their IR spectra to two doubles of sharp, well resolved bands which indicate the presence of two different rotamers stabilized by two modes of weak intramolecular hydrogen bonds with basic N atoms. (iv) In IIICH + 3 • X − and IIICD + 3 • X − salts the perchlorate and iodide anions do not interact at all with the rotating and vibrating N + CH 3 (N + CD 3 ) group but the structures of these salts are not isosteric since the perchlorate anions interact more strongly than iodide anions with the A/B fragment of the IIICH + 3 cations. This is visible from the shapes and intensities of the so-called “ trans ” band in the IR spectra of both salts.

Lack of cytokinin activity of Y-type bases isolated from phenylalanine specific tRNAs

Abstract This work describes the lack of cytokinin activity of Y-type bases. These results clarify contradictory results existing in the literature.

The reactions of thiouracils and thiouridines with chloroacetaldehyde

Abstract Thiouracils and thiouridines were quantitatively modified under mild conditions with aqueous chloroacetaldehyde. The “hydroxyethano” bridged thiouracils, uracil or uridine were formed.

A new outlook on the nature of short intramolecular non-bonded contacts between 6CH⋯O5′ in the crystals of pyrimidine nucleosides and their salts☆

Abstract Short intramolecular contacts between the 6CH group and the O5′ oxygen have been propounded for a long time in the description of structures of some native pyrimidine nucleosides and their derivatives. The character of these interactions was not, however, fully resolved. On the basis of X-ray investigation, it is assumed that these contacts have the character of hydrogen bonds. For some time, however, doubts have been growing as to the validity of this opinion. Consequently we have started detailed investigations to elucidate this problem. Studies carried out for cytidine (Cyd), ethenocytidine (ϵCyd) and their hydrochloride, nitrate, and dihydrogenphosphate salts, were based upon X-ray analysis, IR spectra, and calculations of electron density by the CNDO/2 method. A detailed comparative examination of IR spectra of the eight chosen nucleoside, four of which showed evidence for the presence of such a short contact, proved that the relevant contact could not have the character of an intramolecular hydrogen bond, but instead has a repulsive nature. This conclusion was supported by hypsochromic shifts of the absorption bands of 6CH stretching vibrations participating in short intramolecular contacts, as well as by the positive value of electron density on the carbon atom 6C. On the basis of computer diagrams of the same projectiobs for the crystal structures of all studied compounds, we also tried to find the factors responsible for the existence or absence of the short intramolecular repulsive contact, and to predict the effect of such a contact on the conformational and functional dynamics of nucleic acid fragments.

Crystal and molecular structure of putrescinium hydrogen phosphate dihydrate

AbstractThe X-ray structure of putrescinium hydrogen phosphate dihydrate,