Pepsin‐catalyzed synthesis of protected peptides was studied in two‐phase systems containing up to 50% (by volume) of aqueous phase. A methodological study was carried out to determine the optimum conditions for the synthesis of the model protected peptide Z‐Phe‐Phe‐OMe. Several parameters such as concentrations of carboxylic and amino components, pH of the aqueous phase, ratio of organic to aqueo

Lipase from Candida rugosa immobilized on Celite was employed as the biocatalyst in order to examine the effect of the reaction medium upon enzymic activity and selectivity. As the model reaction, transesterification between tributyrin and pentan‐2‐ol in iso‐octane (2,2,4‐trimethylpentane) was chosen. A small amount of water (0.05%, v/v) was added to the reaction medium. Enhanced transesterificati

αChymotrypsin was modified with cyanuric chloride activated monomethoxypolyethylene glycol (MPEG) with molecular weights 1900 and 5000. Using the higher molecular weight MPEG a product that was soluble in benzene at moderate levels of modification was obtained, whereas with MPEG 1900 almost all the enzyme's amino groups had to be modified for dissolving the conjugate. The catalytic activity decrea

Phosphatidylcholines composed of a hexadecyl chain in the 2-position and a hexyl or octyl chain in the l-position (C6C16PC or C8C16PC) were prepared from dipalmitoylphosphatidylcholine by lipase-catalyzed transesterification; the aqueous phase properties of the products were examined. In the C8C16PC-water system, a lamellar liquid-crystalline phase was dominant. Like all long-chain phosphatidylcho

The composition and content of the gastric phospholipids were followed during development and healing of indometha-cin-induced chronic, antral ulcers in rats. The individual phospholipids were identified by thin-layer chromatography and quantitatively estimated by spectrophotometric analysis of phosphate. No changes were found in phospholipid composition and content after a 24-hour fast or during

Enzymes deposited on solid support usually show good stability when operated in organic solvents. Decreased stability of the enzyme preparations was noticed when low enzyme loadings were used (e.g., with Celite as support; less than 1 mg enzyme/g). It was possible to avoid the activity loss by the addition of an additive which protects the enzyme during the immobilization. Proteins (such as albumi

α‐Chymotrypsin‐catalyzed acyl tranfer was studied using three acyl‐group donors (Mal‐l‐Ala‐l‐Ala‐l‐PheOMe, Bz‐l‐TyrOEt and Ac‐l‐TrpOEt; Mal, maleyl; Bz, benzoyl; OMe, methyl ester; OEt, ethyl ester) and a series of amino‐acid amides. Most of the reactions studied can be described by the simplest kinetic model without the nucleophile binding to the acyl‐enzyme. The α‐chymotrypsin‐catalyzed transfer

Horse liver alcohol dehydrogenase and α-chymotrypsin were deposited on a porous support material, Celite. After equilibration at a well-defined water activity, the catalytic activity was measured with diisopropyl ether as reaction medium. The effects of the presence of polyols and simple saccharides in the preparations were investigated. The additives caused a considerable increase in the amount o

The influence of eight different N-terminal protecting groups (For, Ac, Boc, Fmoc, Mal, Pheac, Aloc and Z) on the α-chymotrypsin-catalyzed synthesis of the dipeptide derivative X-Phe-Leu-NH2 in organic media was studied. Groups such as Ac, For, Boc, Z, Mal, Pheac and Alloc always rendered good peptide yields (92% to 99%) either in acetonitrile or in ethyl acetate. Good correlations were found betw

This paper describes a newly developed technique to adjust and control the water activity in enzymatic reactions in organic media. A saturated salt solution of known water activity is circulated inside a silicone tube, submerged into the reaction medium. The circulating solution can both absorb and release water. Water activity control during lipase catalyzed esterification was demonstrated with d

For s∈ ℝ the weighted Besov space on the unit ball Bd of ℂd is defined by (Formula presented.). Here Rs is a power of the radial derivative operator (Formula presented.), V denotes Lebesgue measure, and ω is a radial weight function not supported on any ball of radius < 1. Our results imply that for all such weights ω and ν, every bounded column multiplication operator (Formula presented.) induces

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder in which autoantibodies and/or autoreactive T cells destroy platelets and megakaryocytes in the spleen and bone marrow, respectively. Thrombopoietin receptor agonists (TPO-RA e.g. Romiplostim and Eltrombopag) have made a substantial contribution to the treatment of patients with ITP, which are refractory to first-line treatments and