Ueber das natürliche Isomere des Leucins

Abstract

Die Constitution des im Jabre 1818 von P r o u s t 3 entdeckten uud bald darauf ron B r a c o n n o t 3 ) und Mulder') naher be8clrriebenen L e u c i n s , das man spaterhiti als eins der wichtigsten und an) haufigsten vorkommenden Spnltungsproducte pflanzlicher und thierischer Eiweise kiirper erkannt hat, ist erst durch die iirbeiten E. S c h u l z e ' s und E. F i s c h e r ' s endgiiltig aufgekllrt worden. Man fasste friiher unter dem Namen Leucin nntiirlich auftretende S m i n o c n p r o n s a u r e n znsamnien. ron denen man glaubte, davs sie je nach ibrer Herkunft eine andere chemische Configuration besassen, und nahm baaptsachlich auf Grund alterer Arbeiten oon L i m p r i c h t H i i f n e r 6 ) und K w i s d n ' ) an, dass dae in der Natur verbreitetste Leucin die a-Amino-Normalcapronsaure darstellt. Diese sich vielfach widersprechenden, irrthiimlichen Anschauungen widerlegten erst E. S c h u l z e und L i k i e r n i k R )im J a b r e 1891, indem sie zeigten, dass das natiirlicbe, in die Raceniverbindung iibergefiihrte Leucin mit der atis Isovaleraldehyd durch die Cyanhvdrin-Reaction syuthetisch erhal teneu a-A m i n oi so b n t y 1 -

A comparison of the nitrogen metabolic networks of Kluyveromyces marxianus and Saccharomyces cerevisiae

“…The former three amino acids were chosen as they represent the most abundant (almost 70% of the nitrogen resource) and the preferred sources of nitrogen of S. cerevisiae in winemaking conditions (Crépin, 2012; Crépin et al ., ) and their redistribution within the de novo proteinogenic amino acids was assessed. The latter three were studied because they are direct precursors of the most common higher alcohols found in wine that are, at least partially, produced through the Ehrlich pathway (Ehrlich, ; Hazelwood et al ., ).…”

“…In yeasts, glycolysis was the first metabolic pathway to be unravelled by Pasteur in 1860 from the puzzle of biochemical reactions obtained in the 1830s (Pasteur, ; Harden, ). In 1904, Ehrlich discovered that the production of ‘fusel’ alcohols derived from amino acid catabolism (Ehrlich, ; Hazelwood et al ., ), and the full Ehrlich pathway was described in 1911 (Neubauer and Fromherz, ). Although many of these pathways appear conserved across yeast species and strains, data suggest that their regulation and the distribution of metabolic fluxes within the cell may vary extensively, thereby making these species and strains unique (Crépin, ; Rollero, ).…”

A study of branched‐chain amino acid aminotransferase and isolation of mutations affecting the catabolism of branched‐chain amino acids in Saccharomyces cerevisiae

“…Until recently, the conventional wisdom was that catabolism then proceeds via a transaminase to yield the corresponding 2-oxoacid, decarboxylation by a 'carboxylase' to an aldehyde that is then reduced in a NADH-linked reaction producing the appropriate fuse1 alcohol [5,8]. The pathway has been called the 'Ehrlich Pathway' because the original concept was formulated by Ehrlich in 1904 [9] and slightly modified a few years later [lo]. This pathway has never been proven to exist and the (mis-named) carboxylase has never been isolated.…”

Flavour-active wine yeasts

“…In particular, 2-phenylethanol is considered to be one of the most important aromatic alcohols contributing to wine flavour. The higher alcohols are predominantly formed by yeast during fermentation from α-keto acids, involving degradation of an amino acid via the so-called Ehrlich pathway (Ehrlich 1904; reviewed by Hazelwood et al 2008; Styger et al 2011b), but can also be synthesised from glucose via pyruvate (Chen 1978; Dickinson et al 1997; Eden et al 2001). The Ehrlich pathway involves three steps: (1) an initial transamination that results in the formation of an α-keto acid; (2) decarboxylation of the α-keto acid to form a ‘fusel aldehyde’; and (3) its reduction to generate the ‘fusel alcohol’.…”