Racematspaltung des D,L‐Typtophans und D,L‐Tyrosins

Abstract

D,L‐Tryptophanmethylester wird mit Dibenzoyl‐D‐weinsäure im Molverhältnis 2:1, D,L‐Tyrosinäthylester mit D‐Weinsäure im Verhältnis 1:2 in äthanolischer Lösung über die diastereomeren Salze in die optischen Antipoden gespalten. Die Estertartrate beider Aminosäuren lassen sich leicht in die antipodischen Esterhydrochloride überführen, aus welchen man nach dem Umkristallisieren die D‐ und L‐Aminosäureester sowie die freien Aminosäuren selbst in optisch reiner Form und guter Ausbeute gewinnt.

Purification, characterization and specificity of chondroitin lyases and glycuronidase from Flavobacterium heparinum

“…Chondroitin AC lyase, glycuronidase and chondroitin B lyase have blocked N-termini similar to that reported for the heparin lyases [13,14]. The DNA-deduced sequence of the related heparin lyase I suggested that its N-terminus was a blocked glutamine, a very unusual finding for a prokaryotic protein [45].…”

“…Their isoelectric points are higher than 7 consistent with them binding and utilizing negatively charged substrates. The pl values of the related heparin lyases from F. heparinum are similar [13,14]. In contrast, chondroitin AC lyase from A. aurescens is an acidic protein having a pl of 5.46 [39].…”

“…Chondroitin AC lyase and chondroitin B lyase demonstrated broad activity optima at pH 6.8 and pH 7.5 respectively. These pH optima were expected since, like heparin lyases (pH optima 6.9-7.6 [13,14]), chondroitin AC and B lyases are probably periplasmic enzymes and thus should act on substrates at or near the pH (6.5-8) optimum for F. heparinum growth. The temperature optimum of chondroitin AC lyase from F. heparinum (40°C) is similar to the related heparin lyases (35-40°C) [13,14] but lower than chondroitin AC lyase from A. aurescens (50°C) [46,47].…”

“…Bacterial degradation of glycosaminoglycans has primarily been studied using enzymes produced from Flavobacterium heparinum [7][8][9][10][11][12]. Three heparin lyases from F. heparinum have recently been purified and characterized by our laboratory [13,14]. Chondroitin with A4,5-unsaturated uronic acid residues at their non-reducing ends.…”

Expanding the Catalytic Promiscuity of Heparinase III from Pedobacter heparinus

“…This monomeric GAG lyase specifically recognizes and cleaves heparan sulfate and heparin that contain the sulfated GlcUA-GlcNAc repeating unit with a-1,4 linkaget hrough a b-elimination process. [7] With the known structure and catalyticm echanism of PhHep III, [8] we used this GAG lyase as an example in the present study to expandt he catalytic promiscuity for a versatile biocatalyst through protein engineering, aiming to provide an ew opportunity for the development of novel enzymes for the degradation of different GAGs.…”