@article { ISI:000258819000009, title = {Characterization of smallest active monomeric penicillin V acylase from new source: a yeast, rhodotorula aurantiaca (NCIM 3425)}, journal = {Process Biochemistry}, volume = {43}, number = {9}, year = {2008}, month = {SEP}, pages = {961-967}, publisher = {ELSEVIER SCI LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

An intracellular monomeric penicillin V acylase (PVA) of 36,000 Da exhibiting pI of 4.19, purified from newly identified yeast source, Rhodotorula aurantiaca (NCIM 3425). The enzyme was purified by hydrophobic interaction chromatography. The enzyme showed optimal activity at 45 degrees C and retained 80\% activity after incubation at 45 degrees C and pH 5.5 for I h. The enzyme showed maximum activity at pH 5.5 and was very stable between pH 5.5-6.5 with optimum stability at pH 6.0. It exhibited 50\% of its original activity after 30 min incubation at 60 degrees C. Enzyme hydrolyzed substrates with benzyl side chain but preferred penicillin V as primary substrate. N-terminally located serine supports the fact that it belongs to Ntn (N-terminal nucleophile)-hydrolase superfamily. The initial ten amino acid residues of R. aurantiaca PVA were identical to the initial sequence of NADH dehydrogenase (EC 1.6.99.3): however the enzyme lacks dehydrogenase activity. EGTA, EDTA, hexane and ethyl acetate stabilized the activity where as small chain alcohols inhibited it. 1,4-Dioxane, THF (tetrahydrofurane), phenol and benzyl alcohol severely inhibited enzyme activity while BME and DTT increased it. Tween 80 and Tween 20 highly enhanced the activity where as SIDS and Triton X-100 inhibited it. (C) 2008 Elsevier Ltd. All rights reserved.

}, keywords = {Intracellular enzyme, N-terminal sequencing, Penicillin V acylase, Purification, Rhodotorula aurantiaca, Substrate specificity}, issn = {1359-5113}, doi = {10.1016/j.procbio.2008.04.024}, author = {Kumar, Atul and Prabhune, Asmita and Suresh, C. G. and Pundle, Archana} } @article { ISI:000264899000012, title = {Effect of organic solvents on cell-bound penicillin V acylase activity of erwinia aroideae (DSMZ 30186): a permeabilization effect}, journal = {Journal of Molecular Catalysis B-Enzymatic}, volume = {57}, number = {1-4}, year = {2009}, month = {MAY}, pages = {67-71}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Erwinia aroideae (DSMZ 30186) is a potential microbial culture to produce intracellular penicillin V acylase (PVA). The whole cell PVA activity was improved by permeabilization with various organic solvents. The cell-bound PVA activity showed an eightfold increase upon treatment with chloroform (5 mu L/mg(dry) (biomass)) for 10 min and diethyl ether (10 mu L/mg(dry) (biomass)) for 45 min. Hexane, toluene, ethyl acetate and dichloromethane enhanced the enzyme activity up to two-, six-, four- and two-fold, respectively; whereas, PVA activity declined drastically on permeabilization with acetone, pyridine and alcohols. The physicochemical properties of the organic solvents used for permeabilization were correlated with the change in activity. It was found that solvents with high hydrophobicity (log P \> 0.68) and lower dielectric constant (\< 9) were relatively effective in increasing PVA activity. These results allow systematic selection of suitable solvent for best performance. (c) 2008 Elsevier B.V. All rights reserved.

}, keywords = {dielectric constant, Erwinia aroideae, Hydrophobicity, Organic solvents, Penicillin V acylase, Permeabilization}, issn = {1381-1177}, doi = {10.1016/j.molcatb.2008.06.018}, author = {Kumar, Atul and Pundle, Archana} } @article { ISI:000271538700006, title = {Rhodotorula aurantiaca penicillin V acylase: active site characterization and fluorometric studies}, journal = {Journal of Photochemistry and Photobiology B-Biology}, volume = {97}, number = {2}, year = {2009}, month = {NOV}, pages = {109-116}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Penicillin V acylase (PVA), a member of newly evolved Ntn-hydrolase superfamily, is a pharmaceutically important enzyme to produce 6-aminopenicillanic acid. Active site characterization of recently purified monomeric PVA from Rhodotorula aurantiaca (Ra-PVA), the yeast source, showed the involvement of serine and tryptophan in the enzyme activity. Modification of the protein with serine and tryptophan specific reagents such as PMSF and NBS showed partial loss of PVA activity and substrate protection. Ra-PVA was found to be a multi-tryptophan protein exhibiting one tryptophan, in native and, four in its denatured condition. Various solute quenchers and substrate were used to probe the microenvironment of the putative reactive tryptophan through fluorescence quenching. The results obtained indicate that the tryptophan residues of Ra-PVA were largely buried in hydrophobic core of the protein matrix. Quenching of the fluorescence by acrylamide was collisional. Acrylamide was the most effective quencher amongst all the used quenchers, which quenched 71.6\% of the total intrinsic fluorescence of the protein, at a very less final concentration of 0.1 M. Surface tryptophan residues were found to have predominantly more electropositively charged amino acids around them, however differentially accessible for ionic quenchers. Denaturation led to shift lambda(max) from 336, in native state, to 357 nm and more exposed to the solvent, consequently increase in fluorescence quenching with all quenchers. This is an attempt towards the conformational studies of Ra-PVA. (C) 2009 Elsevier B.V. All rights reserved.

}, keywords = {active site residues, Fluorometric studies, Penicillin V acylase, Rhodotorula aurantiaca}, issn = {1011-1344}, author = {Kumar, Atul and Gowda, Nagaraj M. and Gaikwad, Sushama M. and Pundle, Archana} }