Continuous Production of N-(Benzyloxycarbonyl)-L-Glycyl-L-Phenylalanine Methyl Ester Utilizing Extractive Reaction in Aqueous/Organic Biphasic Medium
ABSTRACT N-(Benzyloxycarbonyl)-L-glycyl-L-phenylalanine methyl ester was continuously synthesized, enzymatically, utilizing an extractive reaction in an aqueous/organic biphasic system. The extremely high yield, ca.100%, was obtained continuously in a water/butyl acetate biphasic medium.
Continuous enzymatic synthesis of aspartame precursor at low pH using an extractive reaction
Peptides are synthesized in reactions catalyzed by the protease at the optimal pH, although the enzymatic synthesis of peptides at low pH has many advantages from the view point of an industrial-scale production, such as, suppression of nonenzymatic decomposition of amino acid ester substrates and a lower requirement of NaOH for pH adjustment. We developed an extractive synthesis of peptides in an aqueous/organic biphasic system at low pH and applied it to the protease-catalyzed synthesis of N-(benzyloxycarbonyl)-l-aspartyl-l-phenylalanine methyl ester (Z-APM), the precursor of an artificial sweetener, aspartame. The Z-APM yield in a pure aqueous monophasic system is less than 10%, however, it was over 96% at low pH using our extractive synthesis in an aqueous/organic biphasic system although the enzyme activity was very low. The extractive synthesis at low pH has advantages, such as, suppression of substrate inhibition by decreasing the concentration of N-(benzyloxycarbonyl)-l-aspartic acid (Z-l-Asp) in the aqueous phase, and shifting of the chemical equilibrium towards peptide bond formation because of a high distribution of Z-l-Asp to the organic phase. We expect that our method of extractive synthesis at low pH can be applied to other reaction systems.
Warm Hands in Cold Age – On the Need of a New World Order of Care
The world is aging as fertility and mortality are both decreasing. This article focuses on practical care work for the elderly. Such work is done primarily by women even though a larger portion than previously is paid rather than unpaid. All over the world, most elderly care work is organized within the family, most often unpaid. Men receive more care from partners than women, while women receive more care from female relatives. When care work is paid, the payment is generally low. A comparison between Germany, Spain, and Sweden demonstrates similar gender patterns, even though the role of the state in supporting care differs considerably as do care workers' conditions. The sustainability of today's distribution and organization of care work is questioned as the need for care increases, and the possibility of more equal sharing of care work between women and men is explored.