Alkaline “lipase” activity

Lipolysis in mould-ripened varieties is due primarily to the lipases of Penicillium roqueforti or P. camemberti, which secrete potent extracellular lipases. Penicillium lipases are well characterized (see Kinsella and Hwang, 1976 Gripon, 1987,1993). P. camemberti appears to excrete only one lipase which is optimally active at ca. pH 9.0 and at ca. 35°C. P. roqueforti excretes two lipases, one with a pH optimum at 7.5 to 8.0 (or perhaps 9.0 to 9.5), the other at pH 6.0 to 6.5 The acid and alkaline lipases exhibit different specificities. Lipases of Geotrichum candidum have been studied by Side-bottom et al. (1991) and Charlton et al. (1992). This organism produces two lipases of different substrate specificities. 

FIGURE 153 Effect of weak alkaline-soluble fraction (AS) from non-shaved kombu (NSK) and tororokombu (TK) on pancreatic lipase activity in vitro. Lipase activity was measured using a Lipase Kit S according to the manufacturer s protocol. Data are presented as the mean SE (n = 5). p < 0.05, p < 0.005 versus control,... 

Monoglyceride (MG) is one of the most important emulsifiers in food and pharmaceutical industries [280], MG is industrially produced by trans-esterification of fats and oils at high temperature with alkaline catalyst. The synthesis of MG by hydrolysis or glycerolysis of triglyceride (TG) with immobilized lipase attracted attention recently, because it has mild reaction conditions and avoids formation of side products. Silica and celite are often used as immobilization carriers [281], But the immobilized lipase particles are difficult to reuse due to adsorption of glycerol on this carriers [282], PVA/chitosan composite membrane reactor can be used for enzymatic processing of fats and oils. The immobilized activity of lipase was 2.64 IU/cm2 with a recovery of 24%. The membrane reactor was used in a two-phase system reaction to synthesize monoglyceride (MG) by hydrolysis of palm oil, which was reused for at least nine batches with yield of 32-50%. 

Luick, J. R. and Mazrimas, J, A. 1966. Biological effects of ionizing radiation on milk synthesis. III. Effects on milk lipase, esterase, alkaline phosphatase, and lactoper-oxidase activities. J. Dairy Sci. 49, 1500-1504. 

Pasteurization inactivates many enzymes, including alkaline phosphatase and lipoprotein lipase. The absence of active alkaline phosphatase in cheese is often used to determine if the milk has been properly pasteurized prior to cheesemaking. Since pasteurization kills most of the lactic acid bacteria in milk, the lactic acid developed during cheese-... 

There are other hydrolytic enzymes, such as lipases (see below) and alkaline phosphatase, with a mechanism closely related to that of the serine proteases or glyceraldehydephosphate dehydrogenase (GAP-DH) containing a cysteine in the active site. 

Penicillium roqueforti and P. camemberti produce very active extracellular lipases, which are the principal lipolytic agents in mold-ripened cheeses. They preferentially hydrolyze the short-chain fatty acids in milk fat. P. roqueforti produces two lipases, one with an alkaline pH optimum and the other most active at pH 6 6.5, with slightly differing fatty acid specificities (Menassa and Lamberet, 1982). P. camemberti secretes a single lipase with optimal activity at pH 9 (Lamberet and Lenoir, 1976). 

As lipases are proteins, their conformation can be affected by the temperature and pH and, hence, their catalytic activity is expected to have an optimum for these two parameters as happens with most enzymes. The optimum pH for lipase-catalyzed reactions is slightly shifted toward a more alkaline range after immobilization... 

Pancreatic juice contains an alkaline fluid and enzymes, both of which empty into the duodenum. The alkaline pH contributes to neutralization of the acid that empties from the stomach. The enzymes amylase, lipase, trypsin, and chymotrypsin play major roles in the digestion of carbohydrates, fats, and proteins. Trypsin and chymotrypsin are secreted as inactive precursors and are converted to the active forms enzymatically. 

So far, only very little attention has been focussed on the use of zeolites in biocatalysis, i.e., as supports for the immobilization of enzymes. Lie and Molin [116] studied the influence of hydrophobicity (dealuminated mordenite) and hydrophilicity (zeolite NaY) of the support on the adsorption of lipase from Candida cylindracea. The adsorption was achieved by precipitation of the enzyme with acetone. Hydrolysis of triacylglycerols and esterification of fatty acids with glycerol were the reactions studied. It was observed that the nature of the zeolite support has a significant influence on enzyme catalysis. Hydrolysis was blocked on the hydrophobic mordenite, but the esterification reaction was mediated. This reaction was, on the other hand, almost completely suppressed on the hydrophilic faujasite. The adsorption of enzymes on supports was also intensively examined with alkaline phosphatase on bentolite-L clay. The pH of the solution turned out to be very important both for the immobilization and for the activity of the enzyme [117]. Acid phosphatase from potato was immobilized onto zeolite NaX [118]. Also in this study, adsorption conditions were important in causing even multilayer formation of the enzyme on the zeolite. The influence of the cations in the zeolite support was scrutinized as well, and zeolite NaX turned out to be a better adsorbent than LiX orKX. 

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