Heat inactivation

In addition to having the required spedfidty, lipases employed as catalysts for modification of triglycerides must be stable and active under the reaction conditions used. Lipases are usually attached to supports (ie they are immobilised). Catalyst activity and stability depend, therefore, not only on the lipase, but also the support used for its immobilisation. Interesterification reactions are generally run at temperatures up to 70°C with low water availability. Fortunately many immobilised lipases are active and resistant to heat inactivation under conditions of low water availability, but they can be susceptible to inactivation by minor components in oils and fats. If possible, lipases resistant to this type of poisoning should be selected for commercial operations. 

Phosphorylation of HSFl is rapid, and one or more protein kinases are likely to be activated upon HS. An alternative explanation is that heat inactivates a phosphatase which is more active than the HSF kinase at 37 °C. Inactivation of the phosphatase by heat would allow the presumptive heat stable HSF kinase activity to predominate, thus increasing the phosphorylation of HSFl. 

Paleg, L.G., Douglas, T.J., Van Daal, A. Keech, D.B. (1981). Proline and betaine protect enzymes against heat inactivation. Australian Journal of Plant Physiology, 8,107-14. 

Cultures. Swiss 3T3 and A431 cells were grown in a gassed (5.5% COJ, humidified incubator in Dulbecco s Modified Eagle Media (DME) supplemented with 10% heat inactivated fetal calf serum (FCS). 

Culture of Pheochromoqtoma Cells (PC12 Cells). PC12 cells, kindly supplied by Dr. H. Hatanaka of our institute, were maintained in Dulbecco s modified Eagle s medium containing 5% heat-inactivated horse serum. 

Fig. 5. Effect of PGl digestion on the ethylene synthesis-inducing activity of CDTA-soluble tomato pectin (a), Na2C03-soluble tomato pectin (b) and polygalacturonic acid (c). Controls were treated with solutions of heat-inactivated PGl. Treatment doses were 10 /tg of uronic acid equivalents. The line legends shown in panel a apply to all panels. Bars indicate SEs for the means of measurements of sets of 8 discs/teatment. fr wt, Fresh weight.

Heat inactivations are 5 min at the given temperature. Data are from Knegt et al. 1988. 

B) at the indicated stages, and the PGl, PG2, and total PG activities were determined by differential heat inactivation. Each time point is the average of at least two separate extractions assayed in duplicate. The developmental stages are MG, mature green Br, breaker stage, (time of first external color development) and +2, +5, +7, and +10 are days after breaker. 

Both the active enzyme, the heat-inactivated enzyme from Sulfurospirillum (Dehalos-pirillum) multivorans, and cyanocobalamin are capable of dehalogenating haloacetates (Nenmann et al. 2002), and the rate of abiotic dehalogenation depends on the catalyst that is nsed. 

Hewitt, J., Rivera-Aban, M., and Greening, G. E. (2009). Evaluation of murine norovirus as a surrogate for human norovirus and hepatitis A virus in heat inactivation studies. J. Appl. Microbiol. 107, 65-71. 

Studies on the active agent of the yeast extract have shown it to be nondialyzable, heat labile, and inactivated by trypsin and chymotrypsin as well as silver ions and p-hydroxymercuribenzoate.(7l) These and other properties suggest that the active agent is an enzyme. Sedimentation studies have shown that the yeast photoreactivating enzyme combines with UV-irradiated DNA, in which condition it is more resistant to heat inactivation and inactivation due to silver ions and p-hydroxymercuribenzoate.<75) The... 

Figure 9.5 Healthy volunteer monocytes after erythrophagocytosis. Rabbit erythrocytes were incubated with heat-inactivated mouse antirabbit erythrocyte serum. Human peripheral blood monocytes (MN) were obtained after Ficoll-Paque isolation and monocyte clumping with subsequent separation from lymphocytes, yielding a 95 % pure MN population. Non-ingested erythrocytes were removed by hypotonic lysis.

Add 5 ml Antibiotic-Antimycotic (lOOx, cat. 15240-062) and 50 ml heat-inactivated horse serum (cat. 16050-122) to make complete MEM (used for neuron plating and glial culture). For neuron plating, the complete MEM could be kept for a couple of months at 4°. However, for glial culture, a freshly thawed serum aliquot should be used for each culture. Obvious growth retardation in glial culture is observed when using 1-month-old complete MEM stored at 4°. 

FIGURE 8.10 H2S consumption in rat aorta smooth muscle cells (RASMCs). Accumulated data from several experiments showing RASMC H2S consumption rates (filled circles and squares) as a function of H2S concentration, compared to H2S oxidation rates in solution without cells (open circles and squares). Heat-inactivated RASMC H2S consumption rates (open plus symbols) were equivalent to background rates without cells. Inset Representative PHSS traces showing stepwise additions of Na2S stock, at arrows, in the presence (thin line) and absence (thick line) of RASMCs (after [41]). 

Torreggiani, D. and Toledo, R.T. 1986. Influence of sugars on heat inactivation, injury and repair of Saccharomyces cerevisiae. J. Food Sci. 51, 211-215. 

There is little new information available on the heat inactivation of fungal PG. Weitnauer,48 using a questionable technique47 of viscosity measurements and entirely disregarding the possible effect of PM, found that the PG solutions were inactivated by holding for a few hours at 40° and that there is a noticeable drop in activity even at 30°. This is in good harmony with the common experience that the PG activity in solu-... 

Solutions of tomato and tobacco PM in the pH range 4-6 will resist heat inactivation at temperatures up to 60° for at least an hour.26 Above 60° the enzyme is rapidly inactivated. Orange PM is reported21 to be inactivated at 45° at pH 7.5 and to suffer slow inactivation even at 5° especially at pH values higher or lower than 7.5. This is in contrast to tomato PM, which retains its activity practically undiminished for many... 

They also suggested the lipids were released and became extractable primarily through enzymatic reactions after maceration of the leaves for extraction. Thus, they postulated that the time interval between maceration of the plant tissue and the application of heat to coagulate proteins was critical. They recommended heat inactivation of enzymes and precipitation of proteins as quickly as possible after maceration to minimize this interference. 

Standard tests, dialysis, heat inactivation, and the effects of changing the pH on the catalytic activity of the preparations, were all consistent with the idea that enzymes had the properties ascribed to proteins. Between 1920 and 1930 increasing numbers of enzymes were isolated by Willstatter and partially purified. Assays for purification and the extent achieved were not sufficiently rigorous to exclude the possi-... 

Lactam-forming activity in rat liver microsomes has been demonstrated with the cyclization of 2-(carbamoyloxy)benzoates (11.139) and 2-(sulfamoyl-oxy)benzoates (11.141) (R = alkyl or aryl R = H, Cl, Br, Me) [158], Good yields (60 - 80%) of the products 11.140 and 11.142, respectively, were obtained following incubation for 20 h at 20 - 25°. Incubation at 35 - 37° yielded mostly salicylamides 11.143, i.e., the common products of ring hydrolysis. No reaction was seen with heat-inactivated microsomes, seemingly ruling out nonenzymatic cyclization. Again, similarity with Sect. 8.5.7 is clear. 

Growth medium RPMI-1640 with L-glutamine (Irvine Scientific Co., Irvine, CA), supplemented with 10% heat-inactivated fetal bovine serum, lOIU/mL penicillin, lOOpg/mL streptomycin (PEST), 50pM2-mercaptoethanol, 292 igl mL L-glutamine, and lOmM HEPES buffer (all from Sigma-Aldrich). 

Pertussis toxin has a high mitogenic potential. This can be avoided by heat inactivation for 20 min in an 80°C water bath. 

In general, serum should be heat-inactivated by heating at 56°C for 15 min to inactivate complement components prior to ammonium sulfate fractionation. Ascitic fluid should first be filtered through a cushion of glass wool. 

DMEM high glucose, trypsin-EDTA solution, fetal bovine serum (FBS), heat inactivated (all from Invitrogen). 

Primary CLL cells purified from peripheral blood of volunteer patients (see Note 3) CLL cells are purified by Ficoll gradient centrifugation, by negative selection, or by a combination of both (see Note 4). CLL cells can be used immediately or frozen in 90% heat/inactivated FBS supplemented with 10% DMSO and stored at -80°C or in liquid nitrogen for short-and long-term storage, respectively. CLL cells are cultured in complete RPMI medium and maintained in a humidified atmosphere of 5% CO at 37°C (see Note 5). 

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