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G Miech

Publications and source records attributed to G Miech.

At least 19 recordsLinked to original sources
PubMed1992

Only prolidase I activity is present in human plasma.

1. After ion exchange chromatographic separation, liver prolidase exhibits two isoforms (prolidase I and II). 2. The activity of both was explored in human and rat tissues, and in normal and cytolytic human plasma. 3. The activity of prolidase I, eluted at the lowest ionic strength, was stimulated by 24 hr of preincubation with 1 mM MnCl2, but prolidase II activity was strongly inhibited by this long preincubation. In both normal and cytolytic human plasma, chromatographic separation also disclosed that only prolidase I activity was present. 4. This isoform displayed properties resembling those of liver and kidney prolidase I. 5. To explain the absence of prolidase II activity from the plasma, we tested the possibility that its tissue distribution differed. 6. However, this was not substantiated by the distribution found, or by the location, molecular weight and behavior of human liver prolidase II after neuraminidase treatment. 7. We also explored the hypothesis that plasma proteins inhibit prolidase II activity, and found that albumin almost abolished this activity after 6 hr incubation.

Animals↗
PubMed1988

Prolinase activity in prolidase-deficient fibroblasts.

The activity of prolinase (EC 3.4.13.8) was studied in cultured skin fibroblasts derived from three patients with deficient prolidase (EC 3.4.13.9). With pro-val as substrate and manganese in the reaction buffer, prolinase activity was higher in prolidase-deficient cells than in control cells (mean (SEM) 917 (67) nmol min-1 mg-1, n = 3, control mean (SEM) 294, (50), n = 11). The Michaelis constants were not different for the pro-val and progly substrates in control and prolidase deficient fibroblasts. However, the constants for Vmax rose for both substrates in deficient cells. These results demonstrate that prolinase activity increases in prolidase-deficient fibroblasts as also shown in the plasma of patients with prolidase deficiency. We suggest that in prolidase-deficient fibroblasts, this rise in prolinase activity constitutes an attempt to compensate for the prolidase deficiency by increasing the greatly reduced intracellular proline pool.

Adult↗
PubMed1987

Changes in prolinase and prolidase activity during CCl4 administration inducing liver cytolysis and fibrosis in rat.

In earlier papers, we reported that the activity of prolidase (EC 3.4.13.9) increased in the plasma of patients with cirrhosis, while that of serum prolinase (EC 3.4.13.8) was normal and was affected only by necrosis. In this work, we investigated prolinase and prolidase activity during short and long-term CCL4 administration in the rat. After a single dose, prolinase activity increased in serum faster than did prolidase activity and it also decreased more slowly. Within the liver, no significant change in these two enzyme activities was observed during the acute phase of necrosis. During chronic CCl4 intoxication, the rises in prolidase and prolinase activity in rat serum were difficult to interpret, because of the liver necrosis present throughout the experiment. However, within the liver, prolinase activity was not affected, unlike that of prolidase which rose at week 3, reached a maximum value at week 6 (reversible fibrosis) and remained elevated at weeks 10 and 12 (irreversible fibrosis). The increase in prolidase activity was specific for liver and was not observed in other tissues. These results are in agreement with those obtained in humans; they highlight the possible physiological significance of enhanced liver prolidase activity during the fibrotic process.

Alanine Transaminase↗