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Biomedical subjects

A J Hay

Publications and source records attributed to A J Hay.

At least 91 records · Page 5Linked to original sources
PubMed1977

Influenza virus messenger RNAs are incomplete transcripts of the genome RNAs.

The results of ribonuclease T1 oligonucleotide fingerprint analyses indicate that influenza virus messenger RNAs are incomplete transcripts of the corresponding genome RNAs and that in this respect they differ from the unpolyadenylated virus specific complementary RNAs obtained from infected cells. From the position of the untranscribed oligonucleotide in the virus RNA sequence and the ability or inability of the different transcripts to protect the 5' terminal nucleotide of virus RNAs against nuclease S1 digestion, it is concluded that whereas the unpolyadenylated cRNAs are complete transcripts, the polyadenylated messenger RNAs lack sequences complementary to the 5' end of the genome molecules.

Animals↗
PubMed1977

Characterization of virus-specific messenger RNAs from avian fibroblasts infected with fowl plague virus.

In cell-free protein synthesizing systems from wheat embryos, messenger RNAs extracted from chick embryo fibroblasts infected with fowl plague virus direct the synthesis of nine virus-specific polypeptides, two of which may be related to the virus-specific glycopolypeptides. All of the mRNAs are complementary in sequence to virion RNA, and RNAs which do not contain poly A appear to be translated as efficiently as their polyadenylated counterparts. Under certain conditions of incubation, virion RNA also directs the synthesis of discrete polypeptides but these products are not detected in infected cells.

Animals↗
PubMed1970

Purification and properties of alpha-D-mannosidase from the limpet, Patella vulgata.

1. alpha-Mannosidase from the limpet, Patella vulgata, was purified nearly 150-fold, with 40% recovery. beta-N-Acetylglucosaminidase was removed from the preparation by treatment with ethanol. The final product was virtually free from beta-galactosidase. 2. Limpet alpha-mannosidase was assayed at pH3.5 and at this pH it was necessary to add Zn(2+) for full activity. At pH5, the enzyme had the same activity in the presence or absence of added Zn(2+). 3. On incubation at acid pH, the enzyme underwent reversible inactivation, which was prevented by adding Zn(2+). 4. EDTA accelerated inactivation and the addition of Zn(2+) at once restored activity. No other cation was found to reactivate the enzyme. 5. Cl(-) had an unspecific effect on hydrolysis by limpet alpha-mannosidase. It increased the rate of reaction with substrate. The anion did not prevent or reverse inactivation by EDTA. 6. It is concluded that alpha-mannosidase is a metalloenzyme or enzyme-metal ion complex, dissociable at the pH of activity, and that it requires Zn(2+) specifically.

Animals↗
PubMed1969

The enzymic degradation of ovalbumin and its glycopeptides.

1. Ovalbumin glycopeptides, freed from all amino acids other than aspartic acid and a small proportion of leucine by repeated digestion with Pronase, were hydrolysed by 1-aspartamido-beta-N-acetylglucosamine amidohydrolase (glycoaspartamidase) to the corresponding oligosaccharides. The glycoaspartamidase did not attack ovalbumin itself. 2. Ovalbumin, with mannose/hexosamine ratio 5:4, lost 1.5moles of N-acetylglucosamine and more than 2moles of mannose after incubation with alpha-mannosidase and beta-N-acetylglucosaminidase respectively. 3. In ovalbumin glycopeptides with approximate mannose/hexosamine ratios 5:3 and 5:4, one and two N-acetylglucosamine residues respectively were accessible to the action of beta-N-acetylglucosaminidase. 4. A mixture of alpha-mannosidase and beta-N-acetylglucosaminidase, acting on an ovalbumin glycopeptide with mannose/hexosamine ratio 5:3.7, removed nearly 4moles of mannose and 1.5moles of N-acetylglucosamine. 5. alpha-Mannosidase removed about 1.5moles of mannose from the ovalbumin oligosaccharide with mannose/hexosamine ratio approx. 5:3. The subsequent action of beta-N-acetylglucosaminidase liberated less than 1mole of N-acetylglucosamine and made at least 1mole further of mannose accessible to alpha-mannosidase action. 6. It is concluded that the carbohydrate moiety of ovalbumin is linked through a glycosyl group to asparagine. In a molecule with mannose/hexosamine ratio 5:4, there are two beta-N-acetylglucosamine residues linked together in a terminal position, followed by alpha-mannose. There is also present a side chain containing two alpha-mannose units.

Amidohydrolases↗