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Biomedical subjects

J M Walker

Publications and source records attributed to J M Walker.

At least 343 records · Page 19Linked to original sources
PubMed1972

The primary structure of aspartate aminotransferase from pig heart muscle. Partial sequences determined by digestion with pepsin and trypsi trypsin.

Peptides obtained by tryptic digestion of carboxymethylated and maleylated aspartate aminotransferase and of the aminoethylated enzyme were isolated and the complete amino acid sequences of most of them were determined. Digestion of the carboxymethylated protein with pepsin produced a complex mixture of peptides that allowed some overlapping of the tryptic peptides (Fig. 4); in addition, peptides were obtained that had not been found in either of the tryptic digests. From these studies about 400 amino acid residues were identified. Experimental details and confirmatory data for the results presented here are given in a supplementary paper that has been deposited as Supplementary Publication 50011 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1972) 126, 5.

Alkylation↗
PubMed1970

The origin of human placental oxytocinase.

1. Placentas from normal women and from those with pre-eclamptic toxaemia, taken immediately after labour, were examined for oxytocinase activity and analysed morphometrically.2. Both enzyme activity and volume of syncytiotrophoblast were significantly reduced in placentas from patients with toxaemia.3. There was a positive correlation between the enzyme activity and the proportion of trophoblast in the placenta. When the activity was expressed per unit volume trophoblast, there was very little difference between placentas, whether from normal subjects or from patients with toxaemia.4. It is concluded that human placental oxytocinase is located in the syncytiotrophoblast.

Aminopeptidases↗
PubMed1968

Oxytocinase in plasma and placenta in normal and prolonged labour.

In prolonged labour (dystocia) the level of activity of the enzyme oxytocinase is increased in the plasma and decreased in the placenta; the ratio of its activity in the placenta to that in plasma is less than half that found in normal labour. A possible explanation is that oxytocinase is derived mainly from the placenta and that during prolonged labour the enzyme escapes into the maternal blood stream.

Aminopeptidases↗