Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.2.1.15 (pectinase)
2,440 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mechanism of action for the hydrolysis of polygalacturonic acid by the enzyme endo-polygalacturonase (poly(1,4-alpha-D-galacturonide) glycanohydrolase, EC 3.2.1.15) was investigated. The enzyme from Aspergillus ustus was purified to homogeneity and used for the study. The endo-polygalacturonase had a molecular weight of 36,000 daltons, a pI of 8.3, specific activity of 785 units/mg, Km of 0.82 mg/ml, and Vmax of 976 micromoles of product min-1 mg-1. Amino acids involved in the catalysis were identified by chemical modification and the active site characterized. Inhibition by hydroxynitrobenzyl bromide and diethylpyrocarbonate, followed by substrate protection studies showed that tryptophan and histidine were involved at or near the active site. Kinetic constants of partially inhibited enzyme, suggest the involvement of tryptophan in substrate binding and histidine in catalysis. Quenching of tryptophan fluorescence of the enzyme in the presence of polygalacturonic acid substantiated the conclusion that tryptophan was involved in substrate binding. An isotope effect of 1.8 was observed with deuterated water on the Vmax of the endo-polygalacturonase, with the proton inventory giving a linear relationship. The proposed mechanism involves a single proton transfer from the histidine residue of the enzyme to the glycosidic oxygen and hydrolysis by the addition of a water molecule.
...
PMID:Implication of tryptophan and histidine in the active site of endo-polygalacturonase from Aspergillus ustus: elucidation of the reaction mechanism. 881 23

Solution conformation of polygalacturonase from Aspergillus carbonarius was determined by spectroscopy. UV absorption, second derivative, near-UV CD, fluorescence emission spectra and fluorescence quenching measurements suggest that the tryptophan fluorophores are in a hydrophobic environment. Of the nine tryptophan residues, only one is exposed to the solvent. In the near UV region the enzyme exhibits very weak CD bands, the far UV CD spectrum has a minimum at 218 nm; the enzyme is rich in parallel beta structure. Modification of solvent exposed tryptophan by N-bromosuccinimide resulted in the complete loss of enzyme activity. The enzyme is very sensitive towards urea induced unfolding, with complete loss of activity at 3 M urea concentration.
...
PMID:Conformation of polygalacturonase-II from Aspergillus carbonarius--a spectroscopic study. 950 50

Fusarium moniliforme NCIM 1276 isolated from a tropical mangrove ecosystem produces a single extracellular endo-polygalacturonase with an M(r) of 38 kDa and a carbohydrate content of 4%. It has an alkaline pI of 8.1. The K(m) is 0.12 mg.mL(-1), V(max) is 111.1 micromol.min(-1).mg(-1) and the kcat is 4200 min-1. It has a pH optimum of 4.8. Kinetic and fluorescence data show that tryptophan is involved in binding. An arginine residue at or near the active site may be involved in extended binding of the substrate. A carboxylate and a histidine residue are involved in catalysis. These data are discussed with reference to current literature.
...
PMID:Active site characterization of the single endo-polygalacturonase produced by Fusarium moniliforme NCIM 1276. 1116 25

To invade a plant tissue, phytopathogenic fungi produce several cell wall-degrading enzymes; among them, endopolygalacturonase (PG) catalyzes the fragmentation and solubilization of homogalacturonan. Polygalacturonase-inhibiting proteins (PGIPs), found in the cell wall of many plants, counteract fungal PGs by forming specific complexes with them. We report the crystal structure at 1.73 A resolution of PG from the phytopathogenic fungus Fusarium moniliforme (FmPG). The structure of FmPG was useful to study the mode of interaction of the enzyme with PGIP-2 from Phaseolus vulgaris. Several amino acids of FmPG were mutated, and their contribution to the formation of the complex with PGIP-2 was investigated by surface plasmon resonance. The residues Lys-269 and Arg-267, located inside the active site cleft, and His-188, at the edge of the active site cleft, are critical for the formation of the complex, which is consistent with the observed competitive inhibition of the enzyme played by PGIP-2. The replacement of His-188 with a proline or the insertion of a tryptophan after position 270, variations that both occur in plant PGs, interferes with the formation of the complex. We suggest that these variations are important structural requirements of plant PGs to prevent PGIP binding.
...
PMID:Structural requirements of endopolygalacturonase for the interaction with PGIP (polygalacturonase-inhibiting protein). 1168 32

Family 28 belongs to the largest families of glycoside hydrolases. It covers several enzyme specificities of bacterial, fungal, plant and insect origins. This study deals with all available amino acid sequences of family 28 members. First, it focuses on the detailed analysis of 115 sequences of polygalacturonases yielding their evolutionary tree. The large data set allowed modification of some of the existing family 28 sequence characteristics and to draw the sequence features specific for bacterial and fungal exopolygalacturonases discriminating them from the endopolygalacturonases. The evolutionary tree reflects both the taxonomy and specificity so that bacterial, fungal and plant enzymes form their own clusters, the endo- and exo-mode of action being respected, too. The only insect (animal) representative is most related to fungal endopolygalacturonases. The present study brings further: (i) the analysis of available rhamnogalacturonase sequences; (ii) the elucidation of relatedness between the recently added member, the endo-xylogalacturonan hydrolase and the rest of the family; and (iii) revealing the sequence features characteristic of the individual enzyme specificities and the evolutionary relationships within the entire family 28. The disulfides common for the individual enzyme groups were also proposed. With regard to functionally important residues of polygalacturonases, xylogalacturonan hydrolase possesses all of them, while the rhamnogalacturonases, known to lack the histidine residue (His223; Aspergillus niger polygalacturonase II numbering), have a further tyrosine (Tyr291) replaced by a conserved tryptophan. Evolutionarily, the xylogalacturonan hydrolase is most related to fungal exopolygalacturonases and the rhamnogalacturonases form their own cluster on the adjacent branch.
...
PMID:Pectin degrading glycoside hydrolases of family 28: sequence-structural features, specificities and evolution. 1170 7

A comprehensive study on purification and characterization of the two endopolygalacturonases from Aspergillus niger, PG II and PG IV, accounting for 70% of the total polygalacturonase activity, is reported. These enzymes were purified to homogeneity using ion-exchange chromatography and gel filtration. The enzymes had specific activities of 982 and 3750 units/mg, and their molecular masses were 61 and 38 kDa, respectively. The pH optimum of PG II was pH 3.8-4.3 and for PG IV it was between pH 3 and 4.6, and the temperature optima also differed for the enzymes. The enzymes preferred pectic acid as a substrate, cleaving it at random, leading to the release of oligogalacturonides as products. The K(m) values of the two enzymes were found to be 0.12 and 0.72% respectively. The enzymes were rich in hydrophilic amino acids and relatively low in the sulphur-containing amino acids. Both enzymes were rich in beta-structure and differed in their tertiary folding. The tryptophan residues were in a hydrophobic environment. The enzymes differed in their thermal stability; the midpoint of thermal inactivation, T(m), of the two enzymes was found to be 43 degrees C for PG II and 46 degrees C for PG IV.
...
PMID:A simple fractionation protocol for, and a comprehensive study of the molecular properties of, two major endopolygalacturonases from Aspergillus niger. 1191 53

My professional life has been devoted to the study of microbial products and their biosynthesis, regulation, and overproduction. These have included primary metabolites (glutamic acid, tryptophan, inosinic acid, guanylic acid, vitamin B(12), riboflavin, pantothenic acid, ethanol, and lactic acid) and secondary metabolites (penicillin, cephalosporins, streptomycin, fosfomycin, gramicidin S, rapamycin, indolmycin, microcin B17, fumagillin, mycotoxins, Monascus pigments, and tetramethylpyrazine). Other areas included microbial nutrition, strain improvement, bioconversions of statins and beta-lactams, sporulation and germination, plasmid stability, gel microdroplets, and the production of double-stranded RNA, the polymer xanthan, and enzymes (polygalacturonase, protease, cellulase). Most of the studies were carried out with me by devoted and hardworking industrial scientists for 15 years at Merck & Co. and by similarly characterized students, postdoctorals, and visiting scientists during my 32 years at the Massachusetts Institute of Technology. I owe much of my success to my mentors from academia and industry. My recent research activities with undergraduate students at the Charles A. Dana Research Institute for Scientists Emeriti (R.I.S.E.) at Drew University have been very rewarding and are allowing me to continue my career.
...
PMID:Pickles, pectin, and penicillin. 1548 28

An extracellular pectinase (PECI) was purified to apparent homogeneity from liquid state cultures of the thermophilic fungus Acrophialophora nainiana by ultrafiltration and a combination of gel filtration and ion-exchange chromatographic procedures. The molecular masses of PECI were 35,500 and 30,749 Da, as determined by SDS-PAGE and mass spectrometry, respectively. It was more active at 60 degrees C and pH 8.0 and showed high stability at 50 degrees C with half-life of 7 days. However at 60 and 70 degrees C, PECI was much less stable with half lives of approximately 20 and 3 min, respectively. The thermostability of purified PECI was also investigated by fluorescence and circular dichroism spectroscopy. Fluorescence revealed that the unfolding transition region was observed between 45 and 70 degrees C. A major decrease in the stability was found at 70 degrees C. Circular dichroism measurements at pH between 5.0 and 9.0 showed a transition temperature (T(m)) range of 50-55 degrees . The thermodynamic analysis of these results showed that EPGI is thermal stable protein exhibiting maximum stability (DeltaG(25)) of 22.65 and 19.19 kcal/mol at pH 8.0 and 9.0, respectively. The apparent K(m) value on pectin from citrus fruits was 4.22 mgml(-1). PECI exhibited no detectable activity of pectin methylesterase, endo-polygalacturonase, mannanase, xylanase and cellulase. However, it showed exo-polygalacturonase and pectin lyase activities. The presence of carbohydrate was detected in the pure PECI. It was activated by l-tryptophan, DEPC, DTT, DTNB, DTP, l-cystein and beta-mercaptoethanol and inhibited by NBS, Fe(2+), Cu(2+), Zn(2+), Mn(2+), Al(3+) and Ca(2+). The enzyme showed homology with a pectin lyases from Xanthomonas campestris and Bacillus licheniformis.
...
PMID:Purification and characterization of a novel pectinase from Acrophialophora nainiana with emphasis on its physicochemical properties. 1633 7

Polygalacturonase produced by Streptomyces lydicus was purified to homogeneity by ultrafiltration and a combination of ion exchange and gel filtration chromatographic procedures. The purified enzyme was an exo-polygalacturonase with a molecular weight of 43 kDa. It was optimally active at 50 degrees C and pH 6.0. The enzyme was stable from pH 4.0 to 7.0 and at or below 45 degrees C for 90 min. K(m) value for polygalacturonic acid was 1.63 mg/mL and the corresponding V(max) was 677.8 microM min(-1) mg(-1). The inhibition constant (K(i)) for gluconic acid d-lactone was 20.75 mM. Purified enzyme had been inhibited by N-bromosuccinimide, while l-tryptophan could induce enzyme activity, indicating the involvement of tryptophan at the active site.
...
PMID:Purification and partial characterization of polygalacturonase from Streptomyces lydicus. 1799 45

Acid-induced unfolding of a Tetracoccosporium sp. polygalacturonase enzyme (PG) was studied by a comprehensive series of biophysical and biochemical techniques. At pH 1.0, PG acquires partially folded state, which reveals characteristics of molten globule (MG) state, i.e., reduction of defined tertiary structure with minimal changes in the secondary structure. In this study PG unfolds exposing its hydrophobic surface to a greater extent than the native form at acidic pH with more tryptophan residues exposed to the solvent. Collectively, our data imply the presence of MG state of PG at low pH, suggesting the phenomenon of hydrophobic collapse model for folding and integration into cell membrane.
...
PMID:Characterization of acid-induced partially folded conformation resembling a molten globule state of polygalacturonase from a filamentous fungus Tetracoccosporium sp. 1965 29


1 2 Next >>

---