<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Kumar, Atul</style></author><author><style face="normal" font="default" size="100%">Gowda, Nagaraj M.</style></author><author><style face="normal" font="default" size="100%">Gaikwad, Sushama M.</style></author><author><style face="normal" font="default" size="100%">Pundle, Archana</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Rhodotorula aurantiaca penicillin V acylase: active site characterization and fluorometric studies</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Photochemistry and Photobiology B-Biology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">active site residues</style></keyword><keyword><style  face="normal" font="default" size="100%">Fluorometric studies</style></keyword><keyword><style  face="normal" font="default" size="100%">Penicillin V acylase</style></keyword><keyword><style  face="normal" font="default" size="100%">Rhodotorula aurantiaca</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year><pub-dates><date><style  face="normal" font="default" size="100%">NOV</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">2</style></number><publisher><style face="normal" font="default" size="100%">ELSEVIER SCIENCE SA</style></publisher><pub-location><style face="normal" font="default" size="100%">PO BOX 564, 1001 LAUSANNE, SWITZERLAND</style></pub-location><volume><style face="normal" font="default" size="100%">97</style></volume><pages><style face="normal" font="default" size="100%">109-116</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;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.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><custom3><style face="normal" font="default" size="100%">Foreign</style></custom3><custom4><style face="normal" font="default" size="100%">2.116</style></custom4></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Satyanarayana, L.</style></author><author><style face="normal" font="default" size="100%">Gaikwad, Sushama M.</style></author><author><style face="normal" font="default" size="100%">Balkrishnan, H.</style></author><author><style face="normal" font="default" size="100%">Suresh, C. G.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Crystal structure and fluorescence analysis of alkaline thermostable xylanase from bacillus sp (NCL 87-6-10)</style></title><secondary-title><style face="normal" font="default" size="100%">Protein and Peptide Letters</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">active site residues</style></keyword><keyword><style  face="normal" font="default" size="100%">Alkaline thermophile Bacillus xylanase (ATBXYL-C)</style></keyword><keyword><style  face="normal" font="default" size="100%">fluorescence studies</style></keyword><keyword><style  face="normal" font="default" size="100%">three-dimensional structure</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2013</style></year><pub-dates><date><style  face="normal" font="default" size="100%">FEB</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">2</style></number><publisher><style face="normal" font="default" size="100%">BENTHAM SCIENCE PUBL LTD</style></publisher><pub-location><style face="normal" font="default" size="100%">EXECUTIVE STE Y-2, PO BOX 7917, SAIF ZONE, 1200 BR SHARJAH, U ARAB EMIRATES</style></pub-location><volume><style face="normal" font="default" size="100%">20</style></volume><pages><style face="normal" font="default" size="100%">125-132</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Structural information deduced from the new crystal form of xylanase from Bacillus sp (NCL 87-6-10) (ATBXYL-C) helped us to identify the active site and interpret the stability of the enzyme. The analysis of the tetragonal crystal structure of ATBXYL-C with a bound and cleaved xylotriose revealed the two glutamic acid residues in the structure that could act as nucleophile (Glu94) and base (Glu184) in the enzyme activity and also the tryptophan residues interacting with the substrate. The cleavage of xylotriose in the crystal showed xylobiose to be the major product. Intrinsic fluorescence of the enzyme showed the presence of tryptophans in partially exposed to the solvent at the active site and surface tryptophans in electropositive environment. The titration experiments with xylobiose and xylotriose revealed slightly enhanced preference for longer chain X3 compared with X2. The crystal structure also account for some of the factors, such as increased number of ionic interactions and additional interactions at the N-terminus, which contributed to increased alkalophilicity and thermostability of the enzyme.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;</style></custom3><custom4><style face="normal" font="default" size="100%">1.735</style></custom4></record></records></xml>