Triterpenes from the leaves ofBetula ermanii
SummaryFrom the unsaponifiable fraction of an ethereal extract of the leaves ofBetula ermanii a new triterpene of the dammarane series — 20,24-epoxydammarane-3β,6α,25-trol (II) — and its 6-O-acetyl derivative (I) have been isolated.
Zur Struktur von Zeorin und Leucotylin
Die Isolierung von Zeorin und Leucotylin aus der Flechte Lecanora muralis var. muralis wird beschrieben. Wolff-Kishner-Reduktion von Zeorinon fuhrt zu 6-Desoxy-zeorin, das sich zu 6-Desoxy-zeorinin dehydratisieren last. Letztere beiden Verbindungen sind wahrscheinlich mit Hydroxyhopan bzw. Hopen-I identisch. 22-Desoxy-zeorinon liefert bei der Reduktion nach Wolff-Kishner Zeorinan. Leucotylin last sich mit Chromsaure in Essig-bzw. Schwefelsaure zu zwei verschiedenen Produkten oxydieren. Daraus folgt fur Leucotylin wahrscheinlich die Struktur eines 3-Hydroxy-zeorins.
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.