Biosynthesis of 1-methyladenine by isolated segments of starfish ovaries

Journal Article · Fri Nov 01 04:00:00 EST 1985 · Gen. Comp. Endocrinol.; (United States)

DOI:https://doi.org/10.1016/0016-6480(85)90325-9· OSTI ID:5844577

Tarr, H L

Acid-soluble 1-methyladenine (1-MeA) and an insoluble fraction containing 1-MeA were formed when radioactive L-methionine or adenine (A) were incubated with starfish ovary segments. Attempts to prepare free ribonucleic acid (RNA) from ovaries failed since it was strongly bonded to protein as ribonucleoprotein (RN-P) which was therefore used in studies involving RNA. Incubation of ovary segments with (8-/sup 14/C)adenine-8 (A-8-/sup 14/C) yielded both soluble 1-Me-A-8-/sup 14/C and RN-P-8-/sup 14/C, and similar incubation with L-(methyl-/sup 14/C)methionine yielded soluble 1-MeA-/sup 14/CH/sub 3/ and RN-P-/sup 14/CH/sub 3/. Hydrolysis of RN-P-8-/sup 14/C with 1 N HCl at 100 degrees yielded 91% of the initial radioactivity in the purine fraction, and of this 90% was in A, 9% in 1-MeA, and 1% in 4(5)-amino-5(4)-imidazole carboxamidine (AIMCAD). With RN-P-/sup 14/CH/sub 3/ the corresponding figures were 20, 45, 27, and 28%. Degradation of 1-MeA-8-/sup 14/C or RN-P-8-/sup 14/C with 6 N HCl at 110 degrees yielded radioactive AIMCAD which, on heating at pH 12, gave radioactive 4(5)-amino-5(4)-imidazole carboxamide (AICA). When 1-MeA-/sup 14/CH/sub 3/ or RN-P-/sup 14/CH/sub 3/ were similarly degraded, radioactive AIMCAD was formed, but the AICA possessed little or no radioactivity due to the loss of the radioactive methyl group. Addition of radial nerve factor (GSS) increased the yield of 1-MeA up to 19 times when radioactive L-methionine was substrate, but was ineffective with radioactive A. S-(8-/sup 14/C)Adenosylmethionine was only about 3% as effective as L-(methyl-/sup 14/C)methionine in supporting formation of 1-MeA, and its slight activity was not enhanced by GSS. Immature ovary segments were much more active than those from mature ovaries in synthesizing 1-MeA. The results support the contention that formation of free 1-MeA in starfish ovarian tissues involves methylation of adenine residues in a polynucleotide followed by liberation of 1-MeA by enzymatic hydrolysis.

• OSTI ID: 5844577
• Journal Information: Gen. Comp. Endocrinol.; (United States), Journal Name: Gen. Comp. Endocrinol.; (United States) Vol. 2; ISSN GCENA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADENINES
AMINES
AMINO ACIDS
ANIMALS
ANTIMETABOLITES
AQUATIC ORGANISMS
AROMATICS
AZAARENES
BIOCHEMICAL REACTION KINETICS
BIOSYNTHESIS
BODY
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DRUGS
ECHINODERMS
FEMALE GENITALS
GONADS
HETEROCYCLIC COMPOUNDS
IN VITRO
INVERTEBRATES
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPOTROPIC FACTORS
METHIONINE
METHYLATION
NUCLEIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
OVARIES
PURINES
RADIOACTIVITY
REACTION KINETICS
RNA
SYNTHESIS
TRACER TECHNIQUES