02298nas a2200169   4500008004100000022001400041245016400055210006900219260007100288300001400359490000700373520157900380100001201959700001401971700001101985856013201996       2005                        eng d  a0006-296000aIllustration of HIV-1 protease folding through a molten-globule-like intermediate using an experimental model that implicates alpha-crystallin and calcium ions0 aIllustration of HIV1 protease folding through a moltenglobulelik  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR  a3725-37340 v443 a<p>The folding of HIV-1 protease to its active form involves the coordination of structure formation and dimerization, which follows a hierarchy consisting of folding nuclei spanning from the active site, hinge region, and dimerization domain. However, the biochemical characteristics of the folding intermediates of this protein remain to be elucidated. In an experimental model, the denaturation of the tethered dimer of HIV-1 protease by guanidine hydrochloride revealed an alternative conformation resembling the molten globule state. The molten-globule state binds to the molecular chaperone alpha-crystallin and prevents its aggregation; however, the chaperone alone failed to reconstitute HIV-1 protease into its active form. Calcium ion assisted in the release of active enzyme from the chaperone complex. alpha-crystallin, a member of the small heat-shock protein, assists proteins to fold correctly; however, the underlying principle of signals responsible for chaperone-mediated protein folding remains enigmatic. X-ray photoelectron spectroscopy has been employed to provide the evidence of calcium binding to alpha-crystallin and to decipher the effect of calcium binding on the chaperone-mediated refolding of HIV-1 protease. On the basis of our spectroscopic data, we propose that calcium ions interact with the carboxyl groups of the surface-exposed acidic amino acids of alpha-crystallin bringing electrostatic interference, which plays a pivotal role in inducing conformational changes in the chaperone responsible for the release of the active enzyme.</p>1 aDash, C1 aSastry, M1 aRao, M  uhttps://library.ncl.res.in/content/illustration-hiv-1-protease-folding-through-molten-globule-intermediate-using-experimental-001996nas a2200241   4500008004100000022001400041245019800055210006900253260009500322300001200417490000800429520105500437653001401492653000801506653000901514653002301523653002401546653001001570653001301580100002101593700001101614856012901625       2005                        eng d  a0006-291X00aPurification and properties of a low molecular weight 1,4-beta-D-glucan glucohydrolase having one active site for carboxymethyl cellulose and xylan from an alkalothermophilic Thermomonospora sp0 aPurification and properties of a low molecular weight 14betaDglu  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcAPR  a111-1160 v3293 a<p>A low molecular weight 1,4-beta-D-glucan glucohydrolase from an extracellular culture filtrate of Thermomonospora sp. was purified to homogeneity. The molecular weight of the purified enzyme was 14.2 kDa by MALDI-TOF analysis and is in agreement with SDS-PAGE and gel filtration chromatography. The purified enzyme exhibited both endocarboxymethyl cellulase and endoxylanase activities. A kinetic method was employed to study the active site of the enzyme that hydrolyzes both carboxymethyl cellulose and xylan. The experimental data coincide well with the theoretical values calculated for the case of a single active site. Conformation and microenvironment at the active site was probed with fluorescent chemo-affinity labeling using o-phthalaidehyde as the chemical initiator. Formation of isoindole derivative resulted in complete inactivation of the enzyme to hydrolyze both xylan and CMC as judged by fluorescence studies corroborating a single active site for the hydrolysis of xylan and CMC. (C) 2005 Elsevier Inc. All rights reserved.</p>10aCellulase10aCMC10aOPTA10asingle active site10aThermomonospora sp.10axylan10aXylanase1 aJagtap, Sharmili1 aRao, M  uhttps://library.ncl.res.in/content/purification-and-properties-low-molecular-weight-14-beta-d-glucan-glucohydrolase-having-0