Angiotensin I converting enzyme.
نویسندگان
چکیده
• Interest in particular biologically active substances waxes and wanes. Investigators rush into a newly opened field, solve a few problems, and frequently raise more; then they rush out to follow more promising developments elsewhere. However, interest in angiotensins generally has persisted and increased. Observation of the actions of angiotensins has led to the study of enzymes involved in the metabolism of the liberated peptides, including the angiotensin I converting enzyme. The angiotensin I converting enzyme was discovered by Skeggs and his associates in the mid 1950"s (1-3) when they noticed that horse plasma contains an enzyme that converts angiotensin I to angiotensin II. Renin releases the decapeptide angiotensin I from angiotensinogen. This decapeptide is in turn converted to the octapeptide angiotensin II when the converting enzyme cleaves a histidylleucine dipeptide from the C-terminal end of angiotensin I. The enzyme requires chloride ions and is inhibited by ethylenediaminetetraacetic acid (EDTA). Around the same time Helmer (4, 5) also observed the existence of a factor in plasma that activated his angiotensin preparation. After these discoveries, the matter lay dormant for a long time, no doubt because angiotensin I was not available in pure or synthetic form in substantial quantities. The issue of conversion was kept alive, however, because of the difference between the effects of angiotensin I and angiotensin II on isolated smooth muscle preparations. It was observed that angiotensin I must be converted enzymatically to angiotensin II before it becomes active in most biological systems in vitro (2, 5, 7). (The need for such conversion in vivo is not that noticeable, because the two peptides have similar effects on systemic blood pressure after intravenous injection due to the rapid conversion of angiotensin I in the body.) It has been difficult to measure the
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ورودعنوان ژورنال:
- Circulation research
دوره 36 2 شماره
صفحات -
تاریخ انتشار 1975