Pancreas lipase

The first asymmetric synthesis of (—)-Y-jasmolactone, a fruit fiavor constituent, vas achieved via the enantioselective lactonization (desymmetrization) of a prochiral hydroxy diester promoted by porcine pancreas lipase (PPL) (Figure 6.23) [71]. 

Another approach to the synthesis of chiral non-racemic hydroxyalkyl sulfones used enzyme-catalysed kinetic resolution of racemic substrates. In the first attempt. Porcine pancreas lipase was applied to acylate racemic (3, y and 8-hydroxyalkyl sulfones using trichloroethyl butyrate. Although both enantiomers of the products could be obtained, their enantiomeric excesses were only low to moderate. Recently, we have found that a stereoselective acetylation of racemic p-hydroxyalkyl sulfones can be successfully carried out using several lipases, among which CAL-B and lipase PS (AMANO) proved most efficient. Moreover, application of a dynamic kinetic resolution procedure, in which lipase-promoted kinetic resolution was combined with a concomitant ruthenium-catalysed racem-ization of the substrates, gave the corresponding p-acetoxyalkyl sulfones 8 in yields... 

R) -glycidyl butanoate (RS) -glycidyl butanoate pig pancreas lipase... 

Lipases (triacyl glycerol acyl hydrolases, E.C 3.1.1.3) are a unique class of hydrolases for asymmetric synthesis86,87,S9,90e, They are available from fungi, bacteria and mammalians. The lipases most commonly used so far are the commercially supplied pig pancreas lipase (PPL)136, Pseudomonas cepacia lipase (PCL)89,137 and Candida cylindracea lipase (CCL). In most cases only the crude lipases, consisting of a mixture of proteins which may even be other hydrolases, are successfully applied1373. 

Although quite reliable empirical rules exist for the enantioselectivity of hydrolases for secondary alcohols (see Section 4.2.1.2), such rules are not as developed for primary alcohols, partly because many hydrolases often show low enantioselectivity. With some exceptions, lipases from Pseudomonas sp. and porcine pancreas lipase (PPL) often display sufficient selectivity for practical use. The model described in Figure 4.3 has been developed for Pseudomonas cepacia lipase (reclassified as Burkholderia cepacia), and, provided that no oxygen is attached to the stereogenic center, it works well for this lipase in many cases [41]. However, as soon as primary alcohols are resolved by enzyme catalysis, independent proof of configuration for a previously unknown product is recommended. 

Hog pancreas lipase Succinic anhydride Diethyl ether, room temp, 48 h E 12... 

Other microbial lipases have also been successfully used in anhydrous ionic liquids, e.g., from Alcaligenes sp. (AsL) [54, 58], CaLA, Rhizomucor miehei lipase (RmL), and Thermomyces lanuginosus lipase (TIL) [54]. The lipase from pig pancreas (porcine pancreas lipase, PPL), the only mammalian lipase that has been subjected to ionic liquids, catalyzed transesterificationin[BMIm][NTf2]butnotin[BMIm][PF6]... 

Neri et al89 reported the desymmetrization of A-Boc-serinol 98 by the selective monoacetylation using PPL (porcine pancreas lipase) and vinyl acetate as the acylating agent in organic solvent. The mono acetylated product (R)-99 was obtained after 2 hours with 99% ee and isolated in 69% chemical yield. Traces of the diacetylated product 100 were observed. The cyclization of (R)-99 in basic medium afforded the racemic oxazolidinone 101. The latter was subjected to enzymatic hydrolysis in phosphate buffer affording (R)-... 

Relevant quality control should not be restricted to the usual triad of activities of pancreas lipase, a-amylase, and trypsin, but should be extended to the content of colipasc, the activities of the two other lipolytic enzymes present in pancreatine (phospholipase Aj and carboxylester lipase), and the dissolution characteristics of enteric-coated preparations as a function of time and pH (Fig. 16). The availability of such information will certainly contribute to a better tailoring of flic management of maldigestion in the individual patient and to a more appropriate correction of the obligate nonphysio logical route of delivery of these enzyme supplements. 

Pancreas Lipase, Both are cleared by the kidney and hence are elevated... 

As early as 1984 the porcine pancreas lipase-catalysed enantioselective synthesis of (R)-glycidol was described. At pH 7.8 and ambient temperatures the reaction was allowed to proceed to 60% conversion (Scheme 6.9). This means that the enzyme was not extremely enantioselective, otherwise it would have stopped at 50% conversion. Nonetheless, after workup the (R)-glycidol was obtained in a yield of 45% with an ee of 92% [42]. This was a remarkable achievement and the process was developed into an industrial multi-ton synthesis by Andeno-DSM [34, 43]. While on the one hand a success story, it also demonstrated the shortcomings of a kinetic resolution. Most enzymes are not enantiospecific but enantioselective and thus conversions do not always stop at 50%, reactions need to be fine-tuned to get optimal ees for the desired product [28]. As mentioned above kinetic resolutions only yield 50% of the product, the other enantiomer needs to be recycled. As a result of all these considerations this reaction is a big step forward but many steps remain to be done. 

PPL = Porcine pancreas lipase ANL = Aspergillus Niger lipase... 

PHB was enzymatically synthesized from /3-buty-rolactone (/3-BL).152 Even at a high temperature (100 °C), porcine pancreas lipase (PPL) and lipase CR acted as catalyst to give PHB with Mw up to 7300. 

Glowacz G, Bariszlovich M, Linke M, Richter P, Fuchs C, Morsel JT. Stereoselectivity of lipases in supercritical carbon dioxide. 1. dependence of the regio- and enantioselectivity of porcine pancreas lipase on the water content during the hydrolysis of triolein and its partial glycerides. Chem Phys Lipids 1996 79 101-106. 

The application of ionic liquids in lipase biocatalysis has not remained entirely restricted to CaLB, PcL or CrL. Other lipases have been used in ionic liquids for ester synthesis such as Candida antarctica lipase A (CaLA) [15,16], Thermomyces lanuginosus lipase [17] (TLL), Rhizomucor miehei lipase (PmL), Pseudomonas fluorescens lipase (PJL) [18], Pig pancreas lipase (PpL) [17] and Alcaligenes sp. lipase (A5 L) [16]. 

Srivastava et al. [12] studied the esterification of myristic acid with ethanol with crude hog pancreas lipase. Conversions of up to 76% were obtained under solvent-free conditions while conversions of only up to 37% and 4% were obtained in scCO and acetonitrile, respectively. However, for similar enzyme concentrations, 37% of the myristic acid was converted to ester in scCO, but only 4% was converted in acetonitrile and solvent-free conditions. The alcohol was also found inhibitory for the reaction in scCO. ... 

Before preparing a calibration curve for lipase activity, the detectability of HDI was examined using serum sample spiked with HDI. Linear relationship was obtained (r=0.992) between the concentration of HDI (1.1-17 pmol) and CL intensity. The detection limit of HDI was 0.22 pmol (blank + 3 SD). Calibration curve for lipase activity was prepared by adding porcine pancreas lipase to serum (Table 1). Detection limit for lipase was 1.0 Uhdi (blank + 3 SD), where enzyme activity is expressed as Uhdi one Uhdi corresponds to the amount which liberates 1 pmol HDI per minute at 37 °C from HDI-laurate as a substrate. 

Table 1. Calibration curve for lipase activity in serum spiked with porcine pancreas lipase.

Since the proposed method was optimized for human serum spiked with porcine pancreas lipase, it was applied to real samples to determine its estimated practicability. The seven samples from healthy volunteers were measured by the proposed method and the colorimetric method. The average and median values obtained with the proposed method were 7.76 and 7.67 Uhdi> respectively. The colorimetric method is based on the determination of liberated methylresorufm from... 

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