Aminopeptidases of the small intestinal brush border are strategically located to play a pivotal role in the assimilation of protein nutrients. but the membrane nature of these enzymes has made isolation difficult. Rat intestinal brush borders were solubilized by a papain .p-aminobenzyl cellulose complex and two aminopeptidases purified by zonal gradient centrifugation, Sephadex G-200 gel filtr...

Opioid peptides have been reported to have important functions in human reproduction. Indeed, very high concentrations of enkephalins and their degrading enzymes have been reported in human semen. In the present paper, we compare the activity of two enkephalin-degrading enzymes, aminopeptidase N and neutral endopeptidase 24.11, in different fractions of semen from normozoospermic, fertile men a...

The aminopeptidases constitute a group of enzymes with closely related activities. In clinical chemistry the analysis of the aminopeptidases and of their multiple forms in serum has for a long time been hindered by considerable confusion concerning their identification, and by a lack of characterization. This is in part due to the often large, and sometimes overlapping substrate specificities o...

We found a family with a high activity for hydrolyzing L-alanyl-beta-naphthylamide in their serum. This enzyme was confirmed to be aminopeptidase (microsomal) (EC 3.4.11.2) by means of immunological experiments involving anti-human kidney aminopeptidase (microsomal) antibody. We could not find the cause of the increased activity from the results of clinical and laboratory examinations. The enzy...

The value of assaying urinary alanine aminopeptidase activity was examined. The activity of normal urine was below 2 IU/1. High urinary alanine aminopeptidase was found to suggest the presence of nephritis, pyelonephritis, or other nephrotoxic processes.

The leucine aminopeptidase of Aeromonas proteolytica (EC 3.4.11.10) is a monomeric metalloenzyme having the capacity to bind two Zn2+ atoms in the active site. Structural information of this relatively small aminopeptidase that could illuminate the catalytic mechanism of the metal ions is lacking; hence, we have obtained sequences from the purified enzyme, cloned the corresponding gene, and ex...

The activity of a purified cytosolic aminopeptidase (Mr 79,000) from monkey brain was stimulated about 4-fold by ATP-Mg2+. The stimulation was seen with either synthetic aminopeptidase substrates or natural peptides such as enkephalins. Both ATP and Mg2+ were required for stimulation, and ADP did not inhibit the stimulation. Non-hydrolysable analogues of ATP, deoxy-ATP and other nucleoside trip...

A continuous procedure for the determination of leucine aminopeptidase is described. L-leucinamide is used as substrate and the liberated ammonia is determined with the glutamate dehydrogenase reaction. The enzyme is Mn2+-activated and 30 mumol/l MnCl2 is necessary for an optimal activity measurement. Influence of buffer type, buffer concentration and pH are reported together with the apparent ...

The property of solutions of Triton X-114 to separate into detergent-rich and detergent-poor phases at 30 degrees C has been exploited to investigate the identities of the aminopeptidases in synaptic membrane preparations from pig striatum. When titrated with an antiserum to aminopeptidase N (EC 3.4.11.2), synaptic membranes solubilized with Triton X-100 revealed that this enzyme apparently com...