Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proteins containing a CAAX motif at their carboxyl termini are subject to isoprenylation at the cysteine residue. Proteolytic trimming of isoprenylated proteins is essential in the activation of these proteins. A microsomal endopeptidase activity has been identified which cleaves all-trans farnesylated cysteine containing tetrapeptides between the modified residue and the adjacent amino acid to liberate the modified cysteine residue and an intact tripeptide. Structure/activity studies are reported here on this endopeptidase activity which are consistent with the premise that this protease is identical to the one normally involved in the cellular isoprenylation pathway. The protease only processes peptides which possess an isoprenyl moiety. Within the isoprenyl series, the enzyme hydrolyzes all-trans-farnesyl-, all-trans-geranylgeranyl-, and geranyl-containing peptides. The protease also recognizes the AAX sequence, because the protease behaves either stereospecifically or stereoselectively with respect to the individual amino acids of the tripeptide. The enzyme only measurably hydrolyzes isoprenylated peptides possessing L-amino acids at C and A. On the other hand, there is a small but measurable hydrolysis of isoprenylated peptides containing a D-amino acid at X.
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PMID:Substrate specificity of the isoprenylated protein endoprotease. 144 11

Neurotensin (NT) endopeptidase (EC 3.4.24.16) has been purified about 800-fold from pig brain by four sequential chromatographic steps depending on ion-exchange and hydrophobic interactions. Two types of preparation were studied: one from a Triton X-100-solubilized membrane fraction, and the other from the soluble fraction containing 90% or more of the total activity in the homogenate. NT endopeptidase activity was monitored by high-precision liquid chromatography of the two peptide products, characterized as NT-(1-10) and NT-(1-8), resulting from cleavage of the Pro10-Tyr11 and Arg8-Arg9 bonds respectively. As purification proceeded, from both membranes and cytosol, the yield of the two products achieved a constant ratio of 5:1 and this ratio was reproduced in repeated purifications. However, a distinct peptidase which hydrolysed exclusively at the Arg8-Arg9 bond was partially resolved from NT endopeptidase by chromatography on hydroxyapatite, and this activity was further purified and assigned to endopeptidase-24.15 (EC 3.4.24.15). SDS/PAGE of both preparations of neurotensin endopeptidase revealed a major band of apparent Mr 75000, and treatment of the membrane-associated form with N-Glycanase gave no evidence that the enzyme was a glycoprotein. The membrane-associated and cytosol forms of NT endopeptidase activities, monitored for both NT-(1-10) and NT-(1-8) products, were compared in their responses to 1,10-phenanthroline, EDTA, dithiothreitol (DTT) and some synthetic site-directed inhibitors of endopeptidase-24.15 or peptidyl dipeptidase A. The effects revealed no significant differences between the two preparations, nor did the reagents discriminate between the activities generating the two NT fragments. The partially purified form of endopeptidase-24.15 was also included in this comparison: while some responses were similar, this peptidase was distinguishable in its activation by DTT and its relative resistance to inhibition by EDTA. Both forms of NT endopeptidase were found to hydrolyse other substrates, including Boc-Phe-Ala-Ala-Phe-4-aminobenzoate, bradykinin and substance P (these at faster rates than neurotensin), as well as dynorphin A-(1-8) and luliberin. The bonds hydrolysed in these neuropeptides, as well as in angiotensins I and II and alpha-neoendorphin, were defined. These studies confirm that NT endopeptidase is distinct from endopeptidase-24.15. They further show that the former is a soluble enzyme, not an integral membrane protein, that it is not peptide-specific and that it might be more appropriately named. enzyme, not an integral membrane protein, that it is not peptide-specific and
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PMID:Purification and properties of a neurotensin-degrading endopeptidase from pig brain. 190 21

Internally quenched fluorescent peptides derived from neurotensin (pELYENKPRRPYIL) sequence were synthesized and assayed as substrates for neurolysin (EC 3.4.24.16), thimet oligopeptidase (EC 3.4.24.15 or TOP), and neprilysin (EC 3.4.24.11 or NEP). Abz-LYENKPRRPYILQ-EDDnp (where EDDnp is N-(2,4-dinitrophenyl)ethylenediamine and Abz is ortho-aminobenzoic acid) was derived from neurotensin by the introduction of Q-EDDnp at the C-terminal end of peptide and by the substitution of the pyroglutamic (pE) residue at N-terminus for Abz and a series of shorter peptides was obtained by deletion of amino acids residues from C-terminal, N-terminal, or both sides. Neurolysin and TOP hydrolyzed the substrates at P--Y or Y--I or R--R bonds depending on the sequence and size of the peptides, while NEP cleaved P-Y or Y-I bonds according to its S'(1) specificity. One of these substrates, Abz-NKPRRPQ-EDDnp was a specific and sensitive substrate for neurolysin (k(cat) = 7.0 s(-1), K(m) = 1.19 microM and k(cat)/K(m) = 5882 mM(-1). s(-1)), while it was completely resistant to NEP and poorly hydrolyzed by TOP and also by prolyl oligopeptidase (EC 3.4.21.26). Neurolysin concentrations as low as 1 pM were detected using this substrate under our conditions and its analogue Abz-NKPRAPQ-EDDnp was hydrolyzed by neurolysin with k(cat) = 14.03 s(-1), K(m) = 0.82 microM, and k(cat)/K(m) = 17,110 mM(-1). s(-1), being the best substrate so far described for this peptidase.
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PMID:Selective neurotensin-derived internally quenched fluorogenic substrates for neurolysin (EC 3.4.24.16): comparison with thimet oligopeptidase (EC 3.4.24.15) and neprilysin (EC 3.4.24.11). 1135 59