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Only prolidase I activity is present in human plasma.
1Laboratoire de Biochimie, Université Paris-Sud, Centre d'études pharmaceutiques et biologiques, Châtenay-Malabry, France.
The International Journal of Biochemistry
|March 1, 1992
Summary
Liver prolidase has two isoforms, prolidase I and II. Prolidase I is found in human plasma, while prolidase II activity is inhibited by plasma proteins like albumin.
Area of Science:
- Biochemistry
- Enzymology
Background:
- Prolidase is a dipeptidyl peptidase involved in collagen metabolism.
- Liver prolidase exists in two distinct isoforms, prolidase I and prolidase II.
Purpose of the Study:
- To investigate the properties and distribution of human and rat liver prolidase isoforms.
- To determine the reason for the absence of prolidase II activity in human plasma.
Main Methods:
- Ion exchange chromatography was used to separate prolidase isoforms.
- Enzyme activity assays were performed on tissue extracts and plasma.
- Influence of manganese ions and plasma proteins on enzyme activity was assessed.
Main Results:
- Liver prolidase separated into two isoforms, prolidase I and II.
- Prolidase I activity was stimulated by manganese, while prolidase II was inhibited.
- Only prolidase I activity was detected in human plasma.
- Albumin significantly inhibited prolidase II activity in vitro.
Conclusions:
- Human plasma contains prolidase I, but not prolidase II.
- Plasma proteins, particularly albumin, likely inhibit prolidase II activity, explaining its absence in plasma.