Kelvin K. Ogilvie

Novel substrate of adenosine deaminase.

Adenosine deaminase (from calf intestinal mucosa) converts 8,2′-anhydro-8-mercap to-9-β-D-arabinofuranosyladenine (II)) into 8,2′-anhydro-8-mercapto-9-β-D-arabinofuranosylhypoxanthine (III) with Km of 2.0 × 10−4M and V max equal to 7% that of adenosine. This conversion serves as a useful preparative synthesis of III. Further the fact that II (where the purine base is locked in the anti conformation) is a substrate for the enzyme while 8-bromoadenosine (where the base is in the syn conformation) is not a substrate supports the idea that substrates for adenosine deaminase must exist in the anti conformation.

Injector port reactions in gas chromatography : Sources of error in the quantitative analysis of alkylsilyl derivatives of nucleosides

Abstract The direct monitoring, by gas chromatography, of rates of silylation of various substrates is complicated by accelerated reactions occurring in the hot injector port of the gas chromatograph, e.g. further silylation by excess reagent. Monitoring the hydrolysis of silyl derivatives is also prevented since desilylation by hydrolysis media occurs in the injector port. Techniques have been developed to avoid these injector port reactions and include: (a) deactivation of silylating reagent by reaction with excess methanol, (b) deactivation of substrate by further derivatization with an active reagent, and (c) removal of hydrolysis media in vacuo. The methods are illustrated by studies on the deoxynucleoside thymidine but should be capable of extension to a wide variety of suitable substrates.

Gas chromatographic retention data for silyl and acyl derivatives of nucleosides

Abstract Kovats isothermal retention indices on OV-1 columns are reported for several trimethylsilyl, tert-butyldimethylsilyl, cyclotetramethylene-isopropylsilyl, cyclotetramethylene-tert.-butylsilyl, acetyl and trifluoroacetyl derivatives of thymidine, uridine and 2′-deoxyadenosine, together with a few values for derivatives of 2′-deoxyuridine and adenosine. Retention increments for conversion of O-trimethylsilyl functions to E other functions were found to be reproducible in most cases. Positional differences in the retention increments were observed for conversion to OH in the cases of thymidine, 2′-deoxyuridine and 2′-deoxyadenosine, or to O-trifluoroacetyl groups in the case of thymidine. Positional differences in the increments were also observed in the case of uridine, but were quite variable when unprotected OH groups were present. Uridine derivatives having a 2′-O-trifluoroacetyl group decomposed during gas chromatography. The ability of OV-1 columns to separate isomeric derivatives is also discussed.

Study of rearrangement reactions occurring during gas chromatography of tert.-butyldimethylsilyl ether derivatives of uridine

The gas chromatography of partial O-tert.-butyldimethylsilyl (TBDMS) derivatives of uridine is complicated by the occurrence of a 2′ ↔ 3′ rearrangement of the TBDMS group when uridine derivatives having a 2′- or 3′-O-TBDMS group and an underivatized OH group in the 3′- or 2′-position are injected into a gas chromatograph. When a 5′-O-TBDMS group is also present these rearrangements are accompanied by a thermal decomposition thought to involve elimination of methane. Further derivatization by acetylation or trimethylsilylation (but not trifluoroacetylation), both of which prevent the rearrangement and decomposition reactions, together with gas chromatography-mass spectrometry selected ion recording techniques, is suggested as an analytical procedure for the synthetically useful partial TBDMS derivatives of ribonucleosides.

PHOTOREACTION OF O2,2‘‐ANHYDROURIDINE WITH ETHANOL*

Anhydronucleosides are important analogues of natural nucleosides (Fox, 1969). They have recently been incorporated into nucleotide chains (Ogilvie and Iwacha, 1974; Ogilvie and Slotin, 1973) and have been proposed as intermediates in prebiotic photoinduced formation of polynucleotides (Nagyvary and Nagpal, 1972). The aqueous photolysis of 02,2’-anhydrouridine (1) gives cyclobutane-type dimers similar to those obtained from uracil nucleosides (Ogilvie et a/., 1973). However, the product distribution from the photoinduced reaction of 1 in aqueous ethanol is different from that described recently (Shetlar, 1975) for 1,3-dimethyluracil. The material at R, 0.00 appears to be a mixture of compounds which have not been fully identified. The material at R, 0.15 was applied to Whatman 3 mm paper which was developed for 40 h in solvent B’(n-butanol-ethanol-water; 4: 1 : 5, organic phase used). Two compounds separated and were identified as unreacted 1 (18%) and an ethanol adduct of 1 having the structure 2a (21%). This material was acetylated with acetic anhydride to give a compound X which will be identified below as 2b. The material at R, 0.24 also separated into two components on paper chromatography in solvent B’. These compounds were identified as 02,2’-anhydro-5,6-dihydrouridine (3, 1 1%, identified through

Time-of-flight Secondary Ion Mass Spectrometry of Branched RNA Fragrants: Messenger RNA Splicing Intermedistes

Abstract The negative ion mass spectra generated by a reflecting time-of-flight mass spectrometer are reported for a series of protected oligonucleotides. Quasimolecular and sequence ions have been detected, and the location and nature of protecting groups have been confirmed.

Dimer formation in the photolysis of diacetylanhydrouridine in aqueous solution.

INTRODUCTION THE effects of ultraviolet (UV) radiation on natural nucleic acids has been well documented (Burr, 1968; McLaren, 1964; Setlow, 1968) and the results have given important insight into the effects of radiation on living cells. Recently anhydro (or cycfo) nucleosides have received a great deal of attention as important analogues of natural nucleosides (Fox, 1969; Ikehara, 1969). Anhydronucleosides have been incorporated into anhydronucleotide chains (Ogilvie and Iwacha, 1970; Uesugi et al., 1972) and have been detected as intermediates in proposed prebiotic syntheses of nucleosides (Sanchez and Orgel, 1970; Tapiero and Nagyvary, 197 1). Recently it has been suggested that anhydronucleotides may have been intermediates in the prebiotic synthesis of natural nucleotides and that irradiation may have provided the energy of condensation (Nagyvary and Nagpal, 1972). For these reasons we wish to report some observations on the effects of UV radiation on anhydrouridine derivatives.