Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.5.1.4 (deaminase)
 5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A family of mutant amidases has been derived by experimental evolution of the aliphatic amidase of Pseudomonas aeruginosa strain PAC1. Mutation amiE16, in the structural gene for the enzyme, results in the production of the mutant B amidase by strain B6. This strain, unlike the wild-type, can utilize butyramide for growth. Strain B6 gave rise by a single mutational event to strain V9, utilizing valeramide, and strain PhB3, utilizing phenylacetamide. Strain V9 was not itself able to utilize phenylacetamide but gave rise by mutation to the phenylacetamide-utilizing mutant PhV1. Peptide 108 was isolated from chymotryptic digests of mutant amidases from strains B6, PhB3 and PhV1, but could not be detected in chymotryptic digests of the wild-type amidase. The sequence of peptide 108 was established as Met-Arg-His-Gly-Asp-Ile-Phe. Thermolytic digests of mutant amidases from strains B6, PhB3, PhV1 and V9 were compared with digests of the wild-type amidase. A peptide of the composition Met, Arg, His, Gly2, Asp3, Ile, Ser3, Thr, Val was found in the digest of the wild-type amidase and was replaced in the digests of the mutant amidases by a peptide of the composition Met, Arg, His, Gly2, Asp3, Ile, Ser3, Thr, Val, Phe. Mutation amiE16 is common to the four mutant enzymes and can be accounted for by the mutation Ser leads to Phe. The sequence of the chymotryptic peptide corresponds with the N-terminal sequence of the amidase protein, and can also be related to the thermolysin peptides. It is concluded that mutation amiE16 is a Ser leads to Phe change at position 7 from the N-terminus and the effect of this on the enzyme conformation is discussed.
 ...
PMID:Molecular basis of altered enzyme specificities in a family of mutant amidases from Pseudomonas aeruginosa. 11 34

A low molecular weight protein protease inhibitor was purified from Japanese horseshoe crab (Tachypleus tridentatus) hemocytes. It consisted of a single polypeptide with a total of 61 amino acid residues. This protease inhibitor inhibited stoichiometrically the amidase activity of trypsin (Ki = 4.60 X 10(-10) M), and also had inhibitory effects on alpha-chymotrypsin (Ki = 5.54 X 10(-9) M), elastase (Ki = 7.20 X 10(-8) M), plasmin, and plasma kallikrein. However, it had no effect on T. tridentatus clotting enzyme and factor C, mammalian blood coagulation factors (activated protein C, factor Xa and alpha-thrombin), papain, and thermolysin. The complete amino acid sequence of this inhibitor was determined and its sequence was compared with those of bovine pancreatic trypsin inhibitor (BPTI) and other Kunitz-type inhibitors. It was found that the amino acid sequence of this inhibitor has a high homology of 47 and 43% with those of sea anemone inhibitor 5-II and BPTI, respectively. Thus, this protease inhibitor appeared to be one of the typical Kunitz-type protease inhibitors.
 ...
PMID:Purification and amino acid sequence of Kunitz-type protease inhibitor found in the hemocytes of horseshoe crab (Tachypleus tridentatus). 330 64

Human urinary active kallikrein and prokallikrein were separated on DEAE-cellulose and octyl-Sepharose columns and both purified to homogeneity by affinity chromatography, gel filtration and hydrophobic h.p.l.c. Prokallikrein was monitored during purification by trypsin activation followed by determination of both amidase and kininogenase activity. After trypsin activation, purified prokallikrein had a specific kininogenase activity of 39.4 micrograms of bradykinin equivalent/min per mg and amidase activity of 16.5 mumol/min per mg with D-Val-Leu-Arg-7-amino-4-trifluoromethylcoumarin. Purified active kallikrein had a specific activity of 47 micrograms of bradykinin/min per mg. The molecular mass of prokallikrein was 48 kDa on electrophoresis and 53 kDa on gel filtration whereas active kallikrein gave values of 46 kDa and 53 kDa respectively. Antisera to active and prokallikrein were obtained. In double immunodiffusion and immunoelectrophoresis, antiserum to active kallikrein reacted with active and pro-kallikrein. Antiserum to prokallikrein contained antibodies to determinants not found in active kallikrein, presumably due to the presence of the activation peptide in the proenzyme. Human prokallikrein can be activated by thermolysin, trypsin and human plasma kallikrein. Activation of 50% of the prokallikrein (1.35 microM) was achieved in 30 min with 25 nM-thermolysin, 78 nM-trypsin or 180 nM-human plasma kallikrein. Thus thermolysin was the most effective activator. Thermolysin activated prokallikrein by releasing active kallikrein with N-terminal Ile1-Val2. Thus human tissue (glandular) prokallikrein can be activated by two types of enzymes: serine proteinases, which cleave at the C-terminus of basic amino acids, and by a metalloproteinase that cleaves at the N-terminus of hydrophobic amino acids.
 ...
PMID:Purification of human urinary prokallikrein. Identification of the site of activation by the metalloproteinase thermolysin. 393 23

The lysozyme of bacteriophage T7 is a bifunctional protein that cuts amide bonds in the bacterial cell wall and binds to and inhibits transcription by T7 RNA polymerase. The structure of a mutant T7 lysozyme has been determined by x-ray crystallography and refined at 2.2-A resolution. The protein folds into an alpha/beta-sheet structure that has a prominent cleft. A zinc atom is located in the cleft, bound directly to three amino acids and, through a water molecule, to a fourth. Zinc is required for amidase activity but not for inhibition of T7 RNA polymerase. Alignment of the zinc ligands of T7 lysozyme with those of carboxypeptidase A and thermolysin suggests structural similarity among the catalytic sites for the amidase and these zinc proteases. Mutational analysis identified presumed catalytic residues for amidase activity within the cleft and a surface that appears to be the site of binding to T7 RNA polymerase. Binding of T7 RNA polymerase inhibits amidase activity.
 ...
PMID:The structure of bacteriophage T7 lysozyme, a zinc amidase and an inhibitor of T7 RNA polymerase. 817 Oct 31

This paper describes the enzymatic synthesis of the C-terminal fragment H-Gly-Trp-Met-Asp-Phe-NH2 of cholecystokinin. Immobilized enzymes were used for the formation of all peptide bonds except thermolysin. Beginning the synthesis with phenylacetyl (PhAc) glycine carboxamidomethyl ester (OCam) and H-Trp-OMe by using immobilized papain as biocatalyst in buffered ethyl acetate, the dipeptide methyl ester was then coupled directly with Met-OEt.HCl by alpha-chymotrypsin/Celite 545 in a solvent free system. For the 3+2 coupling PhAc-Gly-Trp-Met-OEt had to be converted into its OCam ester. The other fragment H-Asp(OMe)-Phe-NH2 resulted from the coupling of Cbo-Asp(OMe)-OH with H-Phe-NH2.HCl and thermolysin as catalyst, followed by catalytic hydrogenation. Finally PhAc-Gly-Trp-Met-Asp-Phe-NH2 was obtained in a smooth reaction from PhAc-Gly-Trp-Met-OCam and H-Asp(OMe)-Phe-NH2 with alpha-chymotrypsin/Celite 545 in acetonitrile, followed by basic hydrolysis of the beta-methyl ester. The PhAc-group is removed with penicillin G amidase and CCK-5 is obtained in an overall isolated yield of 19.6%.
 ...
PMID:Total enzymatic synthesis of cholecystokinin CCK-5. 1530 78

AmiD is the fifth identified N-acetylmuramoyl-L-alanine zinc amidase of Escherichia coli. This periplasmic lipoprotein is anchored in the outer membrane and has a broad specificity. AmiD is capable of cleaving the intact peptidoglycan (PG) as well as soluble fragments containing N-acetylmuramic acid regardless of the presence of an anhydro form or not, unlike the four other amidases, AmiA, AmiB, AmiC, and AmpD, which have some specificity. AmiD function is, however, not clearly established but it could be part of the enzymatic machinery involved in the PG turnover in E. coli. We solved three structures of the E. coli zinc amidase AmiD devoid of its lipidic anchorage: the holoenzyme, the apoenzyme in complex with the substrate anhydro-N-acetylmuramic-acid-L-Ala-gamma-d-Glu-L-Lys, and the holoenzyme in complex with the L-Ala-gamma-D-Glu-L-Lys peptide, the product of the hydrolysis of this substrate by AmiD. The AmiD structure shows a relatively flexible N-terminal extension that allows an easy reach of the PG by the enzyme inserted into the outer membrane. The C-terminal domain provides a potential extended geometrical complementarity to the substrate. AmiD shares a common fold with AmpD, the bacteriophage T7 lysozyme, and the PG recognition proteins, which are receptor proteins involved in the innate immune responses of a wide range of organisms. Analysis of the different structures reveals the similarity between the catalytic mechanism of zinc amidases of the AmiD family and the thermolysin-related zinc peptidases.
 ...
PMID:Specific structural features of the N-acetylmuramoyl-L-alanine amidase AmiD from Escherichia coli and mechanistic implications for enzymes of this family. 2003 52