A membrane-bound enzyme which degrades @entity4757 (an undecapeptide) has been purified from @entity1 brain. The properties of this enzyme suggest that it may be involved in the physiological inactivation of the peptide by neural tissues. Enzyme activity was extracted from a membrane fraction of @entity1 diencephalon with a non-ionic detergent, @entity30131 , and activity was monitored by measuring the disappearance of added @entity4757 using radioimmunoassay, bioassay or radiochemical assay. The enzyme was purified about 1000-fold by chromatography on @entity8851 -cellulose, @entity692 and Sephadex gel filtration columns. To identify the cleavage sites in @entity4757 , the peptide was incubated with the purified enzyme and the breakdown products were separated by reverse-phase high-performance liquid chromatography and identified by @entity535 analysis. The results suggested that the enzyme preparation was functionally homogeneous and it cleaved @entity4757 between Gln6-Phe7, Phe7-Phe8 and Phe8-Gly9, with no exopeptidase action. The enzyme had a pH optimum in the range 7--9 and was strongly inhibited by metal-chelating agents, but not affected by most other peptidase inhibitors; it can thus be classified as a neutral metallo-endopeptidase. The enzyme was thermolabile and had a molecular weight of 40 000--50 000 as estimated by gel filtration, density-gradient ultracentrifugation and @entity214 gel electrophoresis. The highly purified substance-P-degrading enzyme could be distinguished from previously described peptidases for which @entity4757 is a substrate. An important feature was that @entity4757 was the preferred substrate among various other neuropeptides tested.

Purification and characterisation of a membrane-bound substance-P-degrading enzyme from XXXX brain.

@entity1 :: ('9606', 'Species') :: ['human'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['amino acid'] @entity692 :: ('MESH:D017886', 'Chemical') :: ['hydroxyapatite'] @entity8851 :: ('MESH:C007369', 'Chemical') :: ['DEAE'] @entity214 :: ('CHEBI:8984', 'Chemical') :: ['sodium dodecylsulphate'] @entity4757 :: ('6863', 'Gene') :: ['substance P'] @entity30131 :: ('MESH:C515901', 'Chemical') :: ['Brij 35']
@entity1 :: (9606,Species) :: ['human']
