scholarly journals Characterization of the substrate specificity of the major cysteine protease (cruzipain) from Trypanosoma cruzi using a portion-mixing combinatorial library and fluorogenic peptides

1997 ◽  
Vol 323 (2) ◽  
pp. 427-433 ◽  
Author(s):  
Elaine DEL NERY ◽  
Maria A. JULIANO ◽  
Morten MELDAL ◽  
Ib SVENDSEN ◽  
Julio SCHARFSTEIN ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Substrate Specificity ◽  
Solid Phase ◽  
Cathepsin L ◽  
Amino Acid Residues ◽  
General Preference ◽  
Human Cathepsin ◽  
Hydrolysis Of ◽  
Positively Charged

The substrate specificity of the major cysteinyl proteinase of the parasitic protozoan Trypanosoma cruzi (cruzipain) was investigated, by combinatorial replacement of amino acid residues at positions P5–P´5, using a fluorescent quenched solid-phase library assay. Positively charged residues appear to be a general preference in the P5–P3 and the P´5–P´3 positions, while a hydrophobic residue was always required at the P2 position. A broad range of amino acids could be accepted at the P´1 position. A clear difference in terms of specificity between cruzipain and human cathepsin L was observed for the accommodation of Pro at the P2 position. The P1 specificity was investigated by a more detailed enzyme kinetic analysis using peptidyl-MCA (where MCA is methylcoumarin amide) and Abz-peptidyl-EDDnp [where Abz is o-aminobenzoic acid and EDDnp is N-(2,4-dinitrophenyl)ethylenediamine] as substrates, and the results were compared with those obtained using human cathepsin L. Cruzipain showed a clear preference for benzyl-Cys or Arg at the P1 position. Human cathepsin L presented similar behaviour to that of cruzipain for the hydrolysis of the ε-NH2-Cap-Leu-Xaa-MCA (where Cap is ε-aminocaproyl) and Abz-Lys-Leu-Xaa-Phe-Ser-Lys-Gln-EDDnp series, whereas the mammalian enzyme was able to tolerate large P1 residues, such as phenylalanine, better than cruzipain in the latter series.

scholarly journals Molecular Cloning and Characterization of Bifidobacterium bifidum 1,2-α-l-Fucosidase (AfcA), a Novel Inverting Glycosidase (Glycoside Hydrolase Family 95)

2004 ◽  
Vol 186 (15) ◽  
pp. 4885-4893 ◽  
Author(s):  
Takane Katayama ◽  
Akiko Sakuma ◽  
Takatoshi Kimura ◽  
Yutaka Makimura ◽  
Jun Hiratake ◽  
...  
Keyword(s):  
Amino Acid ◽  
Genomic Library ◽  
Bifidobacterium Bifidum ◽  
Glycoside Hydrolases ◽  
Glycoside Hydrolase Family ◽  
Amino Acid Residues ◽  
Gene Encoding ◽  
Sugar Chain ◽  
Hydrolysis Of

ABSTRACT A genomic library of Bifidobacterium bifidum constructed in Escherichia coli was screened for the ability to hydrolyze the α-(1→2) linkage of 2′-fucosyllactose, and a gene encoding 1,2-α-l-fucosidase (AfcA) was isolated. The afcA gene was found to comprise 1,959 amino acid residues with a predicted molecular mass of 205 kDa and containing a signal peptide and a membrane anchor at the N and C termini, respectively. A domain responsible for fucosidase activity (the Fuc domain; amino acid residues 577 to 1474) was localized by deletion analysis and then purified as a hexahistidine-tagged protein. The recombinant Fuc domain specifically hydrolyzed the terminal α-(1→2)-fucosidic linkages of various oligosaccharides and a sugar chain of a glycoprotein. The stereochemical course of the hydrolysis of 2′-fucosyllactose was determined to be inversion by using 1H nuclear magnetic resonance. The primary structure of the Fuc domain exhibited no similarity to those of any glycoside hydrolases (GHs) but showed high similarity to those of several hypothetical proteins in a database. Thus, it was revealed that the AfcA protein constitutes a novel inverting GH family (GH family 95).

Detection of peptidases in Trypanosoma cruzi epimastigotes using chromogenic and fluorogenic substrates

Parasitology ◽  
1992 ◽  
Vol 104 (2) ◽  
pp. 315-322 ◽  
Author(s):  
N. Healy ◽  
S. Greig ◽  
H. Enahoro ◽  
H. Roberts ◽  
L. Drake ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Substrate Specificity ◽  
The Other ◽  
Alkaline Ph ◽  
Fluorogenic Substrates ◽  
Ph Profile ◽  
Diisopropyl Fluorophosphate ◽  
Serine Peptidase ◽  
Dipeptidyl Aminopeptidase ◽  
Hydrolysis Of

SUMMARYDetergent extracts of Trypanosoma cruzi epimastigotes catalysed the hydrolysis of a range of amino-acyl and peptidyl p-nitro-anilides and aminomethylcoumarins. At least three enzymes were detected that cleave Z–Phe–Arg–MCA. Two of these were optimally active at alkaline pH, the other at pH 4·0. Of the two enzymes with alkaline pH optima, one was a cysteine peptidase and was unable to cleave Bz–Arg–MCA readily, whilst the other cleaved Bz–Arg–MCA and was inhibited by diisopropyl fluorophosphate. The acidic enzyme was similar to cathespin L of other eukayrotes with respect to its pH profile, substrate-specificity and inhibitor-sensitivity. Evidence was presented that epimastigotes contain a cysteine-type dipeptidyl aminopeptidase, one or more aminopeptidases, and a serine peptidase that cleaves Boc–Ala–Ala–pNA. Digitonin solubilization of the activities from cells supports the hypothesis that the cathespin L-like enzyme and the dipeptidyl aminopeptidase are lysosomal, whilst the Bz–Arg–MCA hydrolase, the aminopeptidases and the Boc–Ala–Ala–pNA serine peptidase are cytosolic.

scholarly journals Amino Acid Residues That Contribute to Substrate Specificity of Class A β-Lactamase SME-1

2005 ◽  
Vol 49 (8) ◽  
pp. 3421-3427 ◽  
Author(s):  
Fahd K. Majiduddin ◽  
Timothy Palzkill
Keyword(s):  
Substrate Specificity ◽  
Active Site ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Class A ◽  
Study Support ◽  
Functional Mutants ◽  
Hydrolysis Of ◽  
Traditional Class

ABSTRACT Carbapenem antibiotics are used as antibiotics of last resort because they possess a broad spectrum of antimicrobial activity and are not easily hydrolyzed by β-lactamases. Recently, class A enzymes, such as the SME-1, NMC-A, and IMI-1 β-lactamases, have been identified with the capacity to hydrolyze carbapenem antibiotics. Traditional class A β-lactamases, such as TEM-1 and SHV-1, are unable to hydrolyze carbapenem antibiotics and exhibit some differences in sequence from those that are able to hydrolyze carbapenem antibiotics. The positions that differ may contribute to the unique substrate specificity of the class A carbapenemase SME-1. Codons in the SME-1 gene representing residues 104, 105, 132, 167, 237, and 241 were randomized by site-directed mutagenesis, and functional mutants were selected for the ability to hydrolyze imipenem, ampicillin, or cefotaxime. Although several positions are important for hydrolysis of β-lactam antibiotics, no single position was found to uniquely contribute to carbapenem hydrolysis. The results of this study support a model whereby the carbapenemase activity of SME-1 is due to a highly distributed set of interactions that subtly alter the structure of the active-site pocket.

scholarly journals Chemical and hydrodynamic characterization of the human leucocyte receptor for complement subcomponent C1q

1989 ◽  
Vol 262 (2) ◽  
pp. 625-631 ◽  
Author(s):  
R Malhotra ◽  
R B Sim
Keyword(s):  
Amino Acid ◽  
Polypeptide Chain ◽  
Solid Phase ◽  
U937 Cells ◽  
Amino Acid Residues ◽  
Human Tonsil ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Complement Component C3

A procedure for preparation of the receptor for complement subcomponent Clq from human tonsil lymphocytes and the monocytic cell line U937 was developed. The procedure is suitable for isolation of several hundred micrograms of the receptor, Clq-R, and has yielded sufficient material for chemical and hydrodynamic characterization. Clq-R from tonsil lymphocytes behaves identically with that from U937 cells. Clq-R has a monomer Mr of 56,000, and is an acidic glycoprotein containing about 17% carbohydrate. The polypeptide chain length is estimated to be 416-448 amino acid residues, with two or three sites for N-linked glycosylation. Detergent-solubilized Clq-R exists as an elongated dimer (f/fo = 1.8), and does not bind a significant weight of detergent. The radioiodinated isolated receptor binds specifically and saturably to solid-phase Clq, but not to collagen, IgG, bovine serum albumin or complement component C3.

Cloning and characterization of human cathepsin L promoter

Gene ◽  
2001 ◽  
Vol 275 (1) ◽  
pp. 93-101 ◽  
Author(s):  
Radhika Bakhshi ◽  
Ashish Goel ◽  
Puneet Seth ◽  
Poonam Chhikara ◽  
Shyam S. Chauhan
Keyword(s):  
Cathepsin L ◽  
Human Cathepsin

scholarly journals Molecular cloning and characterization of a novel β-1,3-xylanase possessing two putative carbohydrate-binding modules from a marine bacterium Vibrio sp. strain AX-4

2005 ◽  
Vol 388 (3) ◽  
pp. 949-957 ◽  
Author(s):  
Masashi KIYOHARA ◽  
Keishi SAKAGUCHI ◽  
Kuniko YAMAGUCHI ◽  
Toshiyoshi ARAKI ◽  
Takashi NAKAMURA ◽  
...  
Keyword(s):  
Glycoside Hydrolase ◽  
Marine Bacterium ◽  
Glycoside Hydrolase Family ◽  
Carbohydrate Binding ◽  
Amino Acid Residues ◽  
Reading Frame ◽  
Carbohydrate Binding Modules ◽  
Hydrolysis Of ◽  
Hydrolase Family

We cloned a novel β-1,3-xylanase gene, consisting of a 1728-bp open reading frame encoding 576 amino acid residues, from a marine bacterium, Vibrio sp. strain AX-4. Sequence analysis revealed that the β-1,3-xylanase is a modular enzyme composed of a putative catalytic module belonging to glycoside hydrolase family 26 and two putative carbohydrate-binding modules belonging to family 31. The recombinant enzyme hydrolysed β-1,3-xylan to yield xylo-oligosaccharides with different numbers of xylose units, mainly xylobiose, xylotriose and xylotetraose. However, the enzyme did not hydrolyse β-1,4-xylan, β-1,4-mannan, β-1,4-glucan, β-1,3-xylobiose or p-nitrophenyl-β-xyloside. When β-1,3-xylo-oligosaccharides were used as the substrate, the kcat value of the enzyme for xylopentaose was found to be 40 times higher than that for xylotetraose, and xylotriose was extremely resistant to hydrolysis by the enzyme. A PSI-BLAST search revealed two possible catalytic Glu residues (Glu-138 as an acid/base catalyst and Glu-234 as a nucleophile), both of which are generally conserved in glycoside hydrolase superfamily A. Replacement of these two conserved Glu residues with Asp and Gln resulted in a significant decrease and complete loss of enzyme activity respectively, without a change in their CD spectra, suggesting that these Glu residues are the catalytic residues of β-1,3-xylanase. The present study also clearly shows that the non-catalytic putative carbohydrate-binding modules play an important role in the hydrolysis of insoluble β-1,3-xylan, but not that of soluble glycol-β-1,3-xylan. Furthermore, repeating a putative carbohydrate-binding module strongly enhanced the hydrolysis of the insoluble substrate.

scholarly journals Roles of Residues Cys69, Asn104, Phe160, Gly232, Ser237, and Asp240 in Extended-Spectrum β-Lactamase Toho-1

2010 ◽  
Vol 55 (1) ◽  
pp. 284-290 ◽  
Author(s):  
Akiko Shimizu-Ibuka ◽  
Mika Oishi ◽  
Shoko Yamada ◽  
Yoshikazu Ishii ◽  
Kiyoshi Mura ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Binding Site ◽  
Kinetic Properties ◽  
Amino Acid Residues ◽  
Class A ◽  
Extended Spectrum ◽  
Hydrolysis Of

ABSTRACTToho-1, which is also designated CTX-M-44, is an extended-spectrum class A β-lactamase that has high activity toward cefotaxime. In this study, we investigated the roles of residues suggested to be critical for the substrate specificity expansion of Toho-1 in previous structural analyses. Six amino acid residues were replaced one by one with amino acids that are often observed in the corresponding position of non-extended-spectrum β-lactamases. The mutants produced inEscherichia colistrains were analyzed both for their kinetic properties and their effect on drug susceptibilities. The results indicate that the substitutions of Asn104 and Ser237 have certain effects on expansion of substrate specificity, while those of Cys69 and Phe160 have less effect, and that of Asp240 has no effect on the hydrolysis of any substrates tested. Gly232, which had been assumed to increase the flexibility of the substrate binding site, was revealed not to be critical for the expansion of substrate specificity of this enzyme, although this substitution resulted in deleterious effects on expression and stability of the enzyme.

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