Hydrolysis of dipeptides by human and ovine placentas
| Autor: | Sharon S. Crandell, Eugene W. Adcock, Frank H. Morriss |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
medicine.medical_specialty
Dipeptidases Placenta Glycine Hydrolysis Leucine Pregnancy Internal medicine medicine Animals Humans chemistry.chemical_classification Sheep biology Venous blood Dipeptides Enzyme assay Amino acid Endocrinology Enzyme medicine.anatomical_structure chemistry Biochemistry Pediatrics Perinatology and Child Health biology.protein Female |
| Zdroj: | Pediatric research. 15(4 Pt 1) |
| ISSN: | 0031-3998 |
| Popis: | Summary: Human and ovine placental tissue homogenates were assayed for dipeptidase activity in vitro. Glycyl-L-leucine, L-leucyl glycine, glycyl-L-lysine, and L-lysyl glycine were hydrolyzed by placental homogenates. The pH optimum for the reaction was 8.0. The relationship between enzyme activity and concentration was linear for placental homogenate concentrations between 0.01 and 0.10 mg protein/ml of reaction mixture. Enzyme activities were 1.92 ± 0.12 (S.E.) μoles/min/mg protein for hydrolysis of glycyl-L-leucine, 0.34 ± 0.06 (S.E.) μmoles/min/mg protein, for hydrolysis of glycy-L-lysine by human placenta, and 2.79 ± 0.8U μmoles/min/mg protein and 0.41 ± 0.25 μmoles/min/mg protein, respectively, by ovine placenta. The infusion of glycyl-L-lucine into the uterine artery of unstressed catheterized pregnant ewes yielded increased concentrations of both component amino acids in uterine venous blood and of leucine in umbilical venous blood. Speculation: The presence of dipeptidase activity in placental homogenates and the observation that glycyl-L-leucine when infused into the main uterine artery is hydrolyzed to its component amino acids support the hypothesis that leucine and possibly glycine extracted from the placenta by the umbilical circulation may be provided by placental hydrolysis of dipeptides which arise within the placenta from the degradation of larger peptides and proteins. |
| Databáze: | OpenAIRE |
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