The interaction of two large beta-galactosidases (from Escherichia coli and from Thermus sp.) with tailor-made anion exchangers was studied. Using lowly activated supports (e.g., containing 2-3 mu mol of ionised groups per wet gram of support), large proteins selectively adsorbed and easily desorbed (e.g., using 200 mM of NaCl), giving highly purified proteins. However, these supports cannot be used to immobilize the enzymes for industrial use, because the weak adsorption.On the other hand, these large proteins strongly adsorb on very highly activated supports (e.g., containing 40 mu mol of ionic groups per wet gram of 4 BCL agarose). Thus, these supports may be not valid for large protein purification, but may be very suitable for immobilization of these proteins. Using high ionic strength (e.g., 300 mM NaCl), large proteins still may be adsorbed on these supports, while only around 20% of total proteins adsorb, permitting some purification of the large proteins but not a total one. Moreover, adsorption under these conditions increase the adsorption strength (now there are not desorption even using 800 mM NaCl).Thus, the purification and the strong reversible immobilization of both beta-galactosidases were performed in a very simple two-step process. The large proteins can be directly adsorbed on these supports after desorption (at 200 mM of NaCl) from poorly activated supports. Furthermore, adsorption on very highly activated supports promotes a significant thermal stabilization of both enzymes, mainly in dissociations conditions. (c) 2006 Elsevier Inc. All rights reserved.

This paper reports experimental study of three measurement techniques in ammoniaemission measurement. Thermo Environmental Instruments (TEI) chemiluminescence ammoniaanalyzer, boric acid scrubber, and litter nitrogen mass balance approach were applied in this broilerlitter ammonia emission study to derive emission fluxes. Litter samples at ages of one-year, twoyear,four-year, five-flock, eight-flock and twelve-flock were treated to different moisture contentlevels and were tested simultaneously by TEI and wet scrubber system. In the meantime, thesamples were also analyzed for total nitrogen contents at the beginning and ending of each test forconducting mass balance analyses. TEI measurements of ammonia concentrations were constantlyhigher than scrubber measurements. However, results by these two methods have a strong linearrelationship. Litter nitrogen mass balance approach yielded the highest emission flux while scrubberdata produced the lowest emission flux among three techniques.

PEI coated supports are proposed in this manuscript as a matrix that may permit a new concept in chromatography. Standard supports have their active groups on a “plane” surface, and permit the interaction with an area accounting for not more than 15–20% of the protein surface. The PEI coated supports permitted the interaction of the protein and a polymeric bead, where the protein may penetrate, permitting the interaction with a larger percentage of the protein surface. Here, we present that PEI coated supports are able to more strongly adsorb proteins that are adsorbed on conventional supports and to adsorb proteins that are not adsorbed on these supports. Moreover, more interestingly, the relative adsorption strength was found to be quite different when using PEI coated supports or conventional supports, because the distribution of charged groups in the protein surface may affect very distinctly to the adsorption when using each of these supports. Thus, some proteins that are very strongly adsorbed on conventional supports (having a small area with many anionic groups) were not among the most strongly adsorbed proteins on PEI coated supports, while some proteins that could not be adsorbed on conventional supports (that is, not having a very rich area in anionic groups) become very strongly adsorbed on PEI supports (very likely because they have dispersed around the surface many anionic groups). That is, the desorption pattern from both kind of supports is very different. We presented the results obtained in the fractioning of crude proteins extract from E. coli and whey protein concentrate. The sequential use of DEAE–agarose and PEI permit to improve the purity of the proteins adsorbed on PEI coated supports by more than a 10-fold factor and their further desorption may give only two to three bands in many instances.

Lipases from Candida rugosa (CRL) and lipase isoforms A and B from Candida antarctica (CAL-A and CAL-B) were adsorbed on aminated supports in the presence of detergents to have individual lipase molecules. Then, one fraction was washed to eliminate the detergent, and both preparations were treated with glutaraldehyde. The presence of detergent during the cross-linking of the lipases to the support permitted an increase in the recovered activity (in some instances, even by a 10-fold factor). This activity was higher even than that exhibited by the just adsorbed lipases, suggesting that it was not a result of some protective effect of the detergent in the enzyme activity during glutaraldehyde chemical modification. Moreover, the enantioselectivity of the different enzyme preparations was very different if the glutaraldehyde was offered in the presence or in the absence of detergent, in some cases increasing the E value (even by a 7-fold factor in the case of CAL-A in the hydrolysis of (+/-)-2-hydroxy-4-phenylbutyric acid ethyl ester), in other cases even inverting the enantio preference (e.g., in the case of CRL). The irreversible chemical inhibition of the enzyme that was immobilized and cross-linked with glutaraldehyde in the presence of detergents was more rapid than that in the other preparations (by more than a 10-fold factor). This experiment reveals an exposition degree of the active serine in the preparation cross-linked with the support in the presence of detergent that is higher than that in the other preparations. The results suggested that different enzyme structures were "stabilized" by the glutaraldehyde treatment if performed in the presence or in the absence of detergent, and that, in the presence of detergent, a form of the lipase with the serine residue more exposed to the medium and much more active could be obtained. This strategy seems to be of general use to improve the lipase activity to be used in macroaqueous media.

Response of ammonia emissions to litter moisture content was investigated under laboratory-controlled conditions. A dynamic, flow-through chamber system was designed to test ammonia emissions from broiler litter samples under various litter moisture contents. It was observed that ammonia emissions are very sensitive to litter moisture content. As water was added to the litter, the NH3-N content in the litter increased. However, measurements of ammonia concentrations in the chamber and total nitrogen loss from litter all suggested that water applied to the litter actually suppressed ammonia emissions for a short time. After enough time ( one week or so) was allowed, higher moisture content in litter can eventually result in higher ammonia emissions. It was also noticed that, at very high litter moisture content, even when extra time was allowed, ammonia concentrations began to decrease as moisture content further increased.