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J R Pattison

Publications and source records attributed to J R Pattison.

68 records · Page 4Linked to original sources

Folic acid and the methylation of homocysteine by Bacillus subtilis.

1. Cell-free extracts of Bacillus subtilis synthesize methionine from serine and homocysteine without added folate. The endogenous folate may be replaced by tetrahydropteroyltriglutamate or an extract of heated Escherichia coli for the overall C(1) transfer, but tetrahydropteroylmonoglutamate is relatively inactive. 2. Extracts of B. subtilis contain serine transhydroxymethylase and 5,10-methylenetetrahydrofolate reductase, which are non-specific with respect to the glutamate content of the folate substrates. Methyl transfer to homocysteine requires a polyglutamate folate as methyl donor. These properties are not affected by growth of the organism with added vitamin B(12). 3. The synthesis of methionine from 5-methyltetrahydropteroyltriglutamate and homocysteine has the characteristics of the cobalamin-independent reaction of E. coli. No evidence for a cobalamin-dependent transmethylation was obtained. 4. S-Adenosylmethionine was not a significant precursor of the methyl group of methionine with cell-free extracts, neither was S-adenosylmethionine generated by methylation of S-adenosylhomocysteine by 5-methyltetrahydrofolate. 5. A procedure for the isolation and analysis of folic acid derivatives from natural sources is described. 6. The folates isolated from lysozyme extracts of B. subtilis are sensitive to folic acid conjugase. One has been identified as 5-formyltetrahydropteroyltriglutamate; the other is possibly a diglutamate folate. 7. A sequence is proposed for methionine biosynthesis in B. subtilis in which methyl groups are generated from serine and transferred to homocysteine by means of a cobalamin-independent pathway mediated by conjugated folate coenzymes.

Alcohol Oxidoreductases↗

Vitamin B(12) in photosynthetic bacteria and methionine synthesis by Rhodopseudomonas spheroides.

1. Assay of some photosynthetic bacteria for vitamin B(12) showed them to be relatively rich in this factor. Rhodopseudomonas spheroides, grown photosynthetically in Co(2+)-supplemented medium, contained about 100mug./g. dry wt. 2. Extracts of wild-type Rps. spheroides methylated homocysteine by a mechanism similar to the cobalamin-dependent pathway present in Escherichia coli. However, no mechanism similar to the cobalamin-independent N(5)-methyltetrahydrofolate-homocysteine transmethylase of E. coli could be detected in Rps. spheroides. 3. N(5)N(10)-Methylenetetrahydrofolate-reductase activity was found in Rps. spheroides. 4. A methionine-requiring mutant strain of Rps. spheroides (strain 2/33), which does not respond to homocysteine, made the same amount of vitamin B(12) as the parent organism. Extracts did not form methionine from N(5)-methyltetrahydrofolate and homocysteine even in the presence of cofactors shown to be necessary with the parent strain, and it is concluded that the mutant is blocked in the formation of the apoenzyme of a homocysteine-methylating system similar to the vitamin B(12)-dependent one in E. coli.

Journal Article↗

Detection of parvovirus DNA in human serum using biotinylated RNA hybridisation probes.

Methods were established for the detection of parvovirus DNA in human serum using single-stranded RNA probes. The sensitivity of detection of virus using 32P-radiolabelled RNA versus non-radiolabelled biotinylated RNA probes using a streptavidin-polyalkaline phosphatase detection system was compared. Virus was detected using 32P-labelled and biotinylated RNA probes at serum dilutions of 10(-3), equivalent to approx. 3 pg of viral DNA. Using biotinylated RNA probes and a dot-blot system, diagnosis of numerous serum samples could be performed within 8 h of receipt of samples, using an RNA probe which was synthesised and stored at -20 degrees C for up to 12 months without loss of sensitivity. Our work demonstrates the potential of biotinylated RNA probes in the routine analysis of viral sequences in serum.

DNA, Viral↗