摘要：

A method has been developed for the chemical assay of the angiotensin converting enzyme. It is based on the fluorimetric determination of histidyl-leucine, a product of the enzymic reaction. It is shown that not only angiotensin I, but also the artificial substrates ZPheHisLeu and ZProPheHisLeu are hydrolysed by the equine and human enzymes. ZPheHisLeu is hydrolysed about 10 times faster than angiotensin I and ZProPheHisLeu by the humanenzyme, and is therefore a convenient substrate for quantitative determinations. Investigations in which this new substrate was utilized showed that human converting enzyme inactivated by dialysis was reactivated by anions in the order . The enzyme activity is highest between pH 7.5 and 8.5.

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