Lipase effects

Hydrolysis of Polyurethanes by Lipase. Effects of Mn of PCL-diol moiety on the hydrolysis of polyurethanes, which were composed of... 

Mezetti, A. Keith, C. Kazlauskas, J., R. Highly enantioselective kinetic resolution of primary alcohols of the type Ph-X-CH(CH3)-CH2OH by Pseudomonas cepacia lipase effect of acyl chain lengh and solvent. Tetrahedron Asymmetry 2003, 14, 3917-3924. 

Sundheim, G., Bengtsson-Olivecrona, G. 1987d. Hydrolysis of bovine and caprine milk fat globules by lipoprotein lipase. Effects of heparin and of skim milk on lipase distribution and on lipolysis. J. Dairy Sci. 70, 2467-2475. 

Wang, C.-S., Martindale, M.E., King., M.M., Tang, J. 1989. Bile-salt-activated lipase effect on kitten growth rate. Am. J. Clin. Nutr. 49, 457 -463. 

Mochizuki, M., Hirano, M., Kanmuri, Y., Kudo, K., and Tokiwa, Y., 1995, Hydrolysis of polycaprolactone fibers by lipase - Effects of draw ratio on enzymatic degradation./ Appl. Polym. Sci. 55 289-296. 

M. Mochizuki, M. Hirano, Y. Kanmuri, K. Kudo and Y. Tokiwa, "Hydrolysis of polycaprolactone fibers by lipase effects of draw ratio on enzymatic degradation"/ Appl Polym. Set, 55, 289-296 (1995). 

Lipases are also active during a certain period of the drying step (51), eg, Lipolase displays maximum activity when the moisture content on the fabric is 20—30% by weight. This means that significant decomposition of any residual fatty matter will take place while the laundry is drying. This hydrolytic activity does not result in an immediate advantage in terms of fat removal however, next time the stained fabric is washed the stain will be removed more effectively. 

Lipases have proven to be effective in prespotters and other liquid detergent formulations when used in undiluted form for pretreatment of tough fatty stains. The low water content on the fabric in this situation is believed to be responsible for the high catalytic activity (50). 

Lipase-catalyzed intermolecular condensation of diacids with diols results in a mixture of macrocycUc lactones and liuear oligomers. Interestingly, the reaction temperature has a strong effect on the product distribution. The condensation of a,(D-diacids with a,(D-dialcohols catalyzed by Candida glindracea or Pseudomonas sp. Upases leads to macrocycUc lactones at temperatures between 55 and 75°C (91), but at lower temperatures (<45°C) the formation of oligomeric esters predorninates. Optically active trimers and pentamers can be produced at room temperature by PPL or Chromobacterium viscosum Upase-catalyzed condensation of bis (2,2,2-trichloroethyl) (+)-3-meth5ladipate and 1,6-hexanediol (92). 

Resolution of Racemic Amines and Amino Acids. Acylases (EC3.5.1.14) are the most commonly used enzymes for the resolution of amino acids. Porcine kidney acylase (PKA) and the fungaly3.spet i//us acylase (AA) are commercially available, inexpensive, and stable. They have broad substrate specificity and hydrolyze a wide spectmm of natural and unnatural A/-acyl amino acids, with exceptionally high enantioselectivity in almost all cases. Moreover, theU enantioselectivity is exceptionally good with most substrates. A general paper on this subject has been pubUshed (106) in which the resolution of over 50 A/-acyl amino acids and analogues is described. Also reported are the stabiUties of the enzymes and the effect of different acyl groups on the rate and selectivity of enzymatic hydrolysis. Some of the substrates that are easily resolved on 10—100 g scale are presented in Figure 4 (106). Lipases are also used for the resolution of A/-acylated amino acids but the rates and optical purities are usually low (107). 

However, whatever the mechanism of action is, the effect of solvents on enzyme selectivity is sometimes really dramatic. For example, Hrrose et al. [42] reported that in the Pseudomonas species lipase-catalyzed desymmetrization of prochiral... 

An example that refers to the third method additives can be employed is described below. Markedly enhanced enantioselectivity was reported for P. cepacia lipase and subtilisin Carlsberg with chiral substrates converted to salts by treatment with numerous Bronsted-Lowry adds or bases [63]. This effect was observed in various organic solvents but not in water, where the salts apparently dissociate to regenerate... 

In 1992, Oda et al. reported a one-pot synthesis of optically active cyanohydrin acetates from aldehydes, which were converted to the corresponding racemic cyanohydrins through transhydrocyanation with acetone cyanohydrin, catalyzed by a a strongly basic anion-exchange resin [46]. The racemic cyanohydrins were acetylated by a lipase from P. cepacia (Amano) with isopropenyl acetate as the acyl donor. The reversible nature of the base-catalyzed transhydrocyanation enabled continuous racemization of the unreacted cyanohydrins, thereby effecting a total conversion (Figure 4.21). 

Tiss, A. Carriere, F. Verger, R. (2001). Effects of gumarabic on lipase interfacial binding and activity. Analytical Biochemistry, Vol. 294, No. 1, Quly 2001) pp. 36-43, ISSN 0003-2697. 

A detailed spectroscopic and theoretical study of the conformation of dioxolanes 1 has appeared <96T8275>, and a theoretical study has shown that the anomeric effect explains the non-planarity of 1,3-dioxole <96JA9850>. The tetraalkynyldioxolanone 2 has been prepared and its structure and reactivity studied <96HCA634>. Both enantiomers of the chiral glycolic acid equivalent 3 can be prepared from D-mannitol <96HCA1696>, and lipase-mediated kinetic... 

Figure 25-8. Control of adipose tissue lipolysis. (TSH, thyroid-stimulating hormone FFA, free fatty acids.) Note the cascade sequence of reactions affording amplification at each step. The lipolytic stimulus is "switched off" by removal of the stimulating hormone the action of lipase phosphatase the inhibition of the lipase and adenylyl cyclase by high concentrations of FFA the inhibition of adenylyl cyclase by adenosine and the removal of cAMP by the action of phosphodiesterase. ACTFI,TSFI, and glucagon may not activate adenylyl cyclase in vivo, since the concentration of each hormone required in vitro is much higher than is found in the circulation. Positive ( ) and negative ( ) regulatory effects are represented by broken lines and substrate flow by solid lines.

In adipose tissue, the effect of the decrease in insulin and increase in glucagon results in inhibition of lipo-genesis, inactivation of lipoprotein lipase, and activation of hormone-sensitive lipase (Chapter 25). This leads to release of increased amounts of glycerol (a substrate for gluconeogenesis in the liver) and free fatty acids, which are used by skeletal muscle and liver as their preferred metabolic fuels, so sparing glucose. 

Seligson s group (95) has published a similar turbidimetric procedure but used nephelometry to measure continuously the effect of lipase on the light scattering of an olive oil emulsion. The instrumentation and approach is the same as that described above for the nephelometric determination of amylase. The method according to the authors is fast and precise with good specificity and sensitivity. The short time required for analysis makes it suitable for emergency use. The technical simplicity permits this method to be easily automated, and it appears to be the lipase method of choice. 

Lozano and co-workers reported an interesting stabilization effect of IL for lipase-catalyzed reaction the authors discovered that the presence of an appropriate substrate was essential for stabilization of enzyme in an IL solvent. The half lifetime of native CAL was only 3.2 h in [emim][PFg] solvent, while it lengthened remarkably to 7500 h in the presence of the substrate. The authors succeeded in demonstrating an efficient lipase-recyclable use system based on SCCO2 solvent (Fig. 9). - ... 

In the reaction, it was essential to use an IL as a co-solvent. Lozano, Iborra and co-workers recently reported an interesting stabilizing effect of two types of water-immiscible ILs ([emim][TFSI] and [BuMe3N][TFSI]) for CAL-B-catalyzed transesterification of vinyl butyrate. The synthetic activity and the stability of the enzyme in these IL solvent systems were markedly enhanced as compared to those in hexane. CAL-B maintained its activity higher than 75% after 4 days of incubation in [emim][TFSI] solvent, while it showed an activity of only 25% when incubated in both water and hexane media at 50°C. Comparison of the ratio of a-helix and (3-sheet by CD spectra showed the activity was closely related with a-helix content which reduced to 31% immediately after lipase was added to hexane and had reached only 2% after 4 days in hexane. On the contrary, no significant reduction of a-helix content was... 

Typical examples of results of activation effect of ILl coating on the lipase PS-catalyzed enantioselective acylation of ( )-l... 

---