Simple alkyl ester derivatives of restaurant grease were prepared using immobilized lipases as biocatalysts. The lipases studied included those of Thermomyces lanuginosa and Candida antarctica supported on granulated silica (gran- T.l. and gran- C.a., respectively), C. antarctica supported on a macroporous acrylic resin (SP435) and Pseudomonas cepacia immobilized within a phyllosilicate sol-gel matrix (IM PS-30). All alcoholysis reactions were carried out in solvent-free media employing a one-step addition of the alcohol to the reaction system. Of the lipases studied, IM PS-30 was found to be the most effective in catalysing the methanolysis and ethanolysis of grease. The processes catalysed by gran- T.l. and gran- C.a. lipases gave poor conversions to esters, and the SP435-catalysed reactions gave intermediate yields of ethyl and methyl esters. Water activity (a(w)) was an important factor in the methanolysis reactions; reaction media with a(w)<0.5 resulted in the highest conversions to methyl esters. Molecular sieves also improved methyl ester yields by as much as 20% in transesterification reactions catalysed by IM PS-30. The immobilized lipases also were evaluated for their ability to produce alkyl esters of grease with several additional normal and branched-chain alcohols.

Ascorbic acid (AA), dehydroascorbic acid (dehydroAA), isoascorbic acid (isoAA), ascorbic acid-Z-phosphate @A-2-PO& and ascorbic acid-2-sulfate (AA-2-SOJ were tested as inhibitors of mushroom polyphenoloxidase (PPO). Kinetic analysis indicated that AA and isoAA were more effective than dehydroAA. The half times (tr,J that decreased 50% of PPO activity for AA, isoAA and dehydroAA were 2.5,3.1, and 1.9 hr, respectively, and the concentrations that inhibited half of PPO activity were as follows: ascorbic acid, 0.04 mM, isoAA, 0.25 mM; and dehydroAA, 7.5 mM. Electron spin resonance studies demonstrated that the Cuz+ of PPO was reduced to Cu+ by AA. AA-2-PO, and AA-2-SO4 were not inhibitors for PPO. However, the digestion of AA-2-PO4 with acid phosphatase yielded AA to inhibit PPO activity. AA-2-SO4 was found to be a poor substrate for sulfatase.

The lipase-catalyzed synthesis of alkyl esters from tallow and grease using Pseudomonas cepacia lipase (PS-30) immobilized within a phyllosilicate sol-gel matrix was investigated. The effects of the presence of alcohol and of the amount of enzyme used were studied. The matrix-immobilized PS-30 lipase effectively converted grease and tallow to ethyl esters in greater than 95% yield when using ethanol. The final conversion of grease or tallow to alkyl esters was aided by the addition of molecular sieves (0.4 wt% of substrates) to the reaction mixture. The matrix-immobilized PS-30 enzyme was easily recovered and could be reused at least five times without losing its activity. Accordingly, the phyllosilicate sol-gel immobilized PS-30 lipase is potentially useful for the economic production of biodiesel fuel.Paper no. J9788 in JAOCS 78, 585-588 (June 2001). FIG. 4. Reusability of free and matrix-immobilized lipase PS-30 in the synthesis of alkyl esters of grease. Reactions were conducted with grease (0.2 mmol), 95% ethanol (0.8 mmol), and matrix-immobilized lipase PS-30 (150 mg) or free lipase (10 mg) at 50°C for 18 h. At the end of each cycle, the enzyme was recovered, washed with hexane, and dried. Fresh substrates were added to start the next reaction: free lipase PS-30 (I), immobilized lipase PS-30 (I I). For manufacturer see Figure 1.

Incubation of mouse myeloma microsomes with GDP-[14Cjmannose results in the biosynthesis of ['4Clmannose phosphoryl dolichol [Baynes, J. W., Hsu, A.-F. & Heath, E. C. (1973) J. Biol. Chem. 248, and a The mouse myeloma tumor, MOPC-46B, synthesizes a kappatype immunoglobulin light chain. This light chain is a glycoprotein of approximately 25,000 molecular weight with a single carbohydrate side chain attached to the peptide chain by an N-glycosidic linkage between N-acetylglucosamine (GlcNAc) and asparagine residue 34 of the protein (1). We recently reported (2) that microsomal preparations from this myeloma tumor catalyze the biosynthesis of mannosylphosphoryl-dolichol (Man-P-Dol), and that this mannolipid serves as a donor of mannosyl residues in the glycosylation of